The MCMP is proud to present over 250 videos on iTunes U! Thanks for all your contributions in the last two years! In 2013 we are introducting 4 new channels: "Logic", "Epistemology", "Philosophy of Science", "Metaphysics and Philosophy of Language". Have fun exploring!

Stephan Hartmann is regarded as one of the leading scholars in the fields of formal epistemology and philosophy of science, and he became a member of the Faculty of Philosophy at LMU last October. Later today (8 May, 2013), at a ceremony in Berlin, Hartmann will officially receive Germany’s most generously endowed prize for distinguished contributions to research, the Alexander von Humboldt Professorship, that brought him back to the land of his birth.

Hartmann now holds the Chair of Philosophy of Science at LMU‘s Munich Center for Mathematical Philosophy (MCMP) and, together with his colleague Hannes Leitgeb, who occupies the Chair of Logic and Philosophy of Language and also holds a Humboldt Professorship, he is actively engaged in extending the interdisciplinary reach of his subject in often surprising directions. The basic goal of the MCMP is to apply advanced mathematical methods to a range of complex philosophical problems.

Born in 1968, Hartmann studied Philosophy and Physics, and has held professorships at the London School of Economics and Political Science (LSE) and, prior to his move to LMU, at Tilburg University in the Netherlands, where he served as Founding Director of the Tilburg Center for Logic and Philosophy of Science. Hartmann is the fourth Humboldt Professor at LMU. The honor had previously been accorded to systems biologist Ulrike Gaul, astrophysicist Georgi Dvali and Hannes Leitgeb. The prestigious awards, administered by the Alexander von Humboldt Foundation and financed by the Federal Ministry for Research, are intended to enable internationally recognized scholars and scientists to carry out long-term, groundbreaking projects at research institutions and universities in Germany.

(LMU press release, Munich, 8 May 2013)

Craig Callender (UCSD) gives a talk at the MCMP/MCTS Workshop on Laws of Nature (17 December, 2012) titled "Building a Better System". Abstract: In this talk I'll sketch the central motivating idea behind Humean approaches to lawhood, namely, that modality arises from bodies of knowledge, not the world (see, e.g., Putnam 1962). Keeping one's eyes firmly focused on this motivation is the key to developing so-called "system" approaches to lawhood. I'll claim that it will suggest particular ways of formulating the best system theory and also replies to recent criticisms. But it will also invite many open questions, such as why do creatures like us modalize at all?

Markus Schrenk (Köln) gives a talk at the MCMP/MCTS Workshop on Laws of Nature (17 December, 2012) titled "Trouble with Properties for Better Best Systems". Abstract: In Lewis' original best system account, the mosaic of point-sized, intrinsic, quiddistic, perfectly natural, fundamental properties is the ultimate material on which everything else, laws of nature in particular, supervenes. While better best system competitions (BBSCs) for different, separate special science property sets aim to apply the same mechanism as Lewis's to get the laws from the distributions of properties (balancing simplicity, strength and fit) it is not so clear: (i) which features properties of the special science have (they are clearly not fundamental, maybe not natural but also not-quiddistic, etc.), (ii) in which kind of entities they are instantiated (clearly not singular space-time points), (iii) how BBSCs deal with vague and extensionless properties, (iv) and what the boundaries are for the different sets of properties which BBSCs take as raw material for allegedly separate competitions. This paper will show that (i) - (iv) are not easy to answer for (us) better best system advocates.

Michael Esfeld (Lausanne) gives a talk at the MCMP/MCTS Workshop on Laws of Nature (17 December, 2012) titled "Humeanism and dispositionalism in physics". Abstract: The paper sets out to make a case for a natural philosophy or naturalized metaphysics that treats physics and metaphysics as inseparable. It examines how Humeanism and dispositionalism about laws of nature fare with respect to classical as well as quantum physics. In particular, I argue that, despite widespread claims to the contrary, Lewis' metaphysics of Humean supervenience is applicable to non-relativistic quantum mechanics and that its application even removes the charge of quidditism. However, this position faces considerable difficulties once physics abandons the assumption of a background system of geometrical relations unifying the world. Against this background, I indicate reasons to prefer dispositionalism to Humeanism.

Helen Beebee (Manchester) gives a talk at the MCMP/MCTS Workshop on Laws of Nature (17 December, 2012) titled "Ramsey vs. Lewis on conditionals and causation". Abstract: In this paper, I explore the prospects for a (very roughly sketched) broadly Pricean perspectivalist account of causation. The ingredient I add to the mix is the thought, familiar from Lewis and others, that causal claims express conditional relationships – except that here the relevant conditional is to be understood in Ramseyan, non-truth-apt terms rather than in terms of Lewis’s machinery of possible worlds. I argue that this approach is much better able than the standard counterfactual approach to account for the close connection between causation and inference.

Mathias Frisch (Maryland) gives a talk at the MCMP/MCTS Workshop on Laws of Nature (17 December, 2012) titled "Why Physics Can't Explain Everything". Abstract: Barry Loewer and David Albert have argued for a view on laws that is at once pragmatic (and takes nomic regularities are summaries of aspects of the Humean mosaic that are useful for beings like us) and 'imperialistic' or foundationalist. I argue in this paper that there is a deep tension between the two planks of the account and suggest that it is the pragmatism and not the foundationalism that is worth keeping.

Stathis Psillos (Athens) gives a talk at the MCMP Colloquium (13 December, 2012) titled "Making Contact with Molecules: On Perrin's Argument for Realism". Abstract: Between roughly 1908 and 1912, there was a turn in the scientific community in favour of the atomic hypothesis. Jean Perrin’s theoretical and experimental work on the causes of Brownian motion played a major role in this shift. When Perrin received the Nobel Prize for physics in 1926, it was noted in the presentation speech that he “put a definite end to the long struggle regarding the real existence of molecules”. The aim of this talk is to cast light on the reasons that explain the shift of opinion concerning the reality of atoms and molecules in the beginning of the twentieth century. The story told will have some rather interesting repercussions concerning the scientific realism debate. After presenting the philosophical debate concerning the role and status of explanatory hypotheses c.1900, (focusing on the work of Ostwald, Poincaré and Boltzmann), I will examine in detail Perrin’s theoretical account of the molecular origins of Brownian motion and explain the structure and the strength of Perrin’s argument for the reality of molecules.

Giovanni Valente (Pittsburgh) gives a talk at the MCMP Colloquium (06 December, 2012) titled "Local Disentanglement in Relativistic Quantum Field Theory". Abstract: In their paper on "Entanglement and Open Systems in Algebraic Quantum Field Theory", Clifton and Halvorson (2001) raised the question whether entanglement between quantum systems can be destroyed by means of local operations and claimed that, contrary to non-relativistic quantum mechanics, this can never be the case in relativistic quantum field theory. In this talk I will argue that Clifton and Halvorson's no-go result applies only to a special kind of local operations, and thereby I will reject their conclusion. In fact, after providing sufficient conditions for local disentanglement to be achieved, I will show that, if the split property holds, there exists a class of local operations which disentangle all states across any pair of spacelike separated quantum field systems.

Peter Adamson (LMU) gives a talk at the MCMP Colloquium (22 November, 2012) titled "Logic as an Instrument in Greek and Arabic Philosophy". Abstract: As is well known, the Aristotelian works on logic were collectively referred to in antiquity as the Organon, meaning "instrument". Ancient Aristotelians took this seriously: for them, logic is not a part of philosophy but only a tool or instrument which one should ideally learn before embarking on the study of philosopher proper. This view was not universally adopted in antiquity, however. The Stoics made logic one of three broad areas of philosophy (along with ethics and physics), and thought of these areas as closely interrelated "parts". In this paper I explore the philosophical consequences of this apparently rather superficial disagreement; for instance, it bears on the question of the extent to which logic was perceived in the ancient world as a "formal" discipline. I also pursue the part vs. instrument debate into the Arabic tradition. There, we find adherents of Aristotle torn between their desire to agree that logic is a mere instrument, and not a part, of philosophy, and their desire to show the importance of logic against its detractors.

Mikael Cozic (Paris) gives a talk at the MCMP Colloquium (22 November, 2012) titled "On Representation Theorems". Abstract: Contemporary decision theory attaches much importance to representation theorems. Representation theorems are mathematical results which establish the equivalence between criteria of preferences and choices among options (e.g., expected utility) and axioms on preferences (e.g., transitivity or independence). Distinct roles can be assigned to these results. One of them is semantic: according to this view, representation theorems allow one to define decision-theoretic involved in the criteria of evaluation (e.g., subjective probability and utility on outcomes for the criterion of expected utility). The aim of this paper is to assess this semantic function by relying on philosophical views on the meaning of theoretical terms.

Thomas Müller (Utrecht) gives a talk at the MCMP Colloquium (21 November, 2012) titled "Toward a formal account of substance via case-intensional logic". Abstract: Things - concrete individuals persisting through time, or more traditionally speaking, substances - are a central ontological category of our commonsensical as well as of our scientific worldview. There is, however, no satisfactory formal account of substance, or so I will argue - despite a plethora of systems of modal and temporal logic available in the literature. I will indicate some of the shortcomings of available accounts by contrasting them with what I take to be a more adequate formal approach.

In my talk, which for a large part is based on joint work with Nuel Belnap (Journal of Philosophical Logic, forthcoming), I will introduce a general logical framework for modality and quantification, called "Case-intensional first-order logic" (CIFOL). CIFOL combines first-order quantification and a universal S5 modality in a straightforward way and is meant to provide a neutral formal framework for discussing various metaphysical and scientific arguments. CIFOL's generality is made possible by an innovation due to Aldo Bressan: All terms (including definite descriptions, variables and constants) have an extension in each case (where the interpretation of the cases is left open; they do not need to be thought of as "possible worlds"), and an intension, which is the function from cases to the case-relative extensions. Predication is intensional (i.e, whether a predicate applies, may depend on more than what is so in a single case). This makes it possible to define a class of so-called absolute predicates, which allow the tracing of a thing from case to case without building into the logical framework metaphysical assumptions about "rigid designation" or "trans-world identity" to handle the reidentification of things. Concrete individuals are thereby seen to be represented not by extensions, as in standard quantified modal logic (in which one tends to think in terms of "inhabitants of possible worlds"), but by intensions. This approach leaves the nature of the extensions completely unspecified - their only systematic role is to figure in case-relative identity statements.

In the second part of the talk, I will switch to specific formal structures of cases that are adequate for representing indeterminism: branching history structures. I will argue that CIFOL based on these structures allows for a detailed discussion of formal aspects of things (substances) and their qualities, and thereby provides a useful formal framework within which, e.g., problems of the identity of substances can be formulated and discussed.

Benjamin Schnieder (Hamburg) gives a talk at the MCMP Colloquium (15 November, 2012) titled "On Ground and Consequence". Abstract: The notion of grounding has proven to be a fruitful tool for philosophical analysis. While traditionally, many explications of core philosophical notions proceeded in purely modal terms, explications in terms of grounding often yield more adequate results. In my talk I will explore a new application of grounding and develop a notion of logical consequence in terms of grounding.

Fabrice Correia (Neuchâtel) gives a talk at the MCMP Colloquium (15 November, 2012) titled "Logical Grounds". Abstract: Philosophers have recently displayed a strong interest in the idea that some facts or truths hold in virtue of - or, as they say, are grounded in - others facts or truths. Grounding come in various sorts, and my talk will focus on logical grounding as opposed to e.g. metaphysical or normative grounding. I will (i) offer a proof-theoretic characterisation of the concept relative to propositional and first-order languages, (ii) show that so characterised, the concept can be used to characterise some notions of truth-in-a-model and various semantic consequence relations, and finally (iii) connect my concept of logical grounding with the notion of groundedness put forward by Kripke in his "Outline of a Theory of Truth".

Michael De (Utrecht) gives a talk at the MCMP Colloquium (14 November, 2012) titled "Classical negation and expansions of FDE" (joint work with Hitoshi Omori (Kobe University, Japan & CUNY, New York)). Abstract: It is sometimes said that classical negation can be recaptured in some systems of non-classical logic. But what exactly *is* classical negation? We endorse and defend one such characterization of classical negation in the context of FDE. We then provide an expansion FDE+ of FDE by this classical negation and show it sound and complete with respect to its intended semantics. Along the way we show that other candidate classical negations to be undefinable in FDE+.

Francesco Paoli (Cagliari) gives a talk at the MCMP Colloquium (14 November, 2012) titled "Semantic minimalism for logical constants". Abstract: In a 2003 paper ("Quine and Slater on paraconsistency and deviance", J. Phil. Log. 32, 2003, pp. 531-548), I defended a minimalist account of meaning for logical constants as a way to ward off Quine's meaning variance charge against deviant logics. Its key idea was that some deviant propositional logics share with classical logic the operational meanings of all their connectives, as encoded in their sequent calculus operational rules, yet validate different sequents than classical logic; therefore, we can have genuine rivalry between logics without meaning variance. In his PhD thesis, Ole Hjortland levelled several objections at this view. The aim of this talk is to address these criticisms, highlighting at the same time the role played by logical consequence in this version of semantic minimalism.

Harvey M. Friedman (OSU) gives a talk at the MCMP Colloquium (31 October, 2012) titled "Concept Calculus". Abstract: Concept Calculus develops theories in first and second order predicate calculus arising from the analysis of various commonsense notions. The systems arising in this way are shown to closely correspond to various well known systems arising in the foundations of mathematics - via mutual interpretations. Initial work on Concept Calculus focused on the general notions of better than and much better than. More recent developments surround a basic notion of universe, based on a principle of plenitude. Universes correspond to Peano Arithmetic. ZFC, and various extensions by large cardinals arise from the axiomatization of various basic kinds of explosions of universes. We discuss some further contexts for Concept Calculus, including the evolutionary universe, and various comparison notions. We believe that any informal conceptual context leads to the natural formulation of axiomatic principles which are mutually interpretable with a range of standard formal systems ranging from PA and fragments, through type theory and ZFC, and the usual strong systems extending ZFC.

Harvey M. Friedman (OSU) gives a talk at the MCMP Colloquium (30 October, 2012) titled "Transcendental Proofs". Abstract: We discuss our Transcendental Proofs project, spanning approximately 45 years, which aims to uncover mathematically fundamental, rich, and diverse subareas of athematics which can only be developed by going well beyond the usual ZFC axioms for mathematics. The discussion will have mathematical, computational, and philosophical components.The mathematical component focuses on long finite sequences, adjacent amsey theorems, finite trees and graphs, continuous maps between countable sets, Borel diagonalization and selection, Boolean Relation Theory, and Embedded Maximal Cliques. The computational component focuses on predictions from higher infinities of the result of actual computations. The philosophical component focuses on various formulations of the project, involving measures of simplicity and naturalness, as well as prospects for confirmation of the validity of transcendental methods.

Luca Incurvati (Cambridge) gives a talk at the Workshop on Groundedness (26-27 October, 2012) titled "That's it, you're grounded!". Abstract: I will begin by reviewing and further defending the minimalist approach to sets which I advanced in earlier work. Then, I will consider the prospects for extending the minimalist approach to the case of semantics. I will conclude by examining whether a minimalist approach prevents us from giving a common account of grounding assumptions in set theory and semantics.

Jönne Speck (Birkbeck) gives a talk at the Workshop on Groundedness (26-27 October, 2012) titled "Grounding Class Theory". Abstract: In this talk, I propose a conception of proper class. It brings together two separate strands of research: metaphysical and semantical groundedness.

On the one hand, I use the *metaphysical* concept of grounding. Whether or not something is a member of a class, I will argue, must be grounded in other facts.

On the other hand, the method of *semantical* groundedness will provide a formal theory that captures this conception of class.

Denis Bonnay (Paris) gives a talk at the Workshop on Groundedness (26-27 October, 2012) titled "Dependence and Groundedness". Abstract: In this talk, I will discuss whether the notion of groundedness can be analyzed directly in terms of dependence upon non-semantic states of affairs or whether a detour via truth and falsity is always necessary.

Kit Fine (NYU) gives a talk at the Workshop on Groundedness (26-27 October, 2012) titled "Ground and Partial Content". Abstract: I provide a ground-theoretic account of partial content.

Øystein Linnebo (Birkbeck/Oslo) gives a talk at the Workshop on Groundedness (26-27 October, 2012) titled "Towards a theory of grounded properties". Abstract: I outline some desiderata for a theory of properties and then examine some attempts to develop an account of 'grounded' properties.

Caspar Storm Hansen (Aberdeen/Oslo) gives a talk at the Workshop on Groundedness (26-27 October, 2012) titled "Alternative Supervaluation for Kripke's Theory of Truth". Abstract: I will present a method of supervaluation for Kripke's theory of truth. It is different from Kripke's own method in that it employs trees, results in a compositional semantics, assigns the intuitively correct truth values to the sentences of a particularly tricky example of Gupta's, and is acceptable as an explication of the correspondence theory of truth.

Toby Meadows (Bristol) gives a talk at the Workshop on Groundedness (26-27 October, 2012) titled "Local Dependence". Abstract: The purpose of this paper is to lay out some groundwork for a general understanding of relationships between: notions of dependence and groundedness; and notions of complexity and cardinality. We commence by sketching a pleasing framework linking dependence with the theory of inductive definitions. We pose a kind of problem for this framework and attempt to explain why this is interesting using a case study from the semantic theory of truth literature. We then attempt to formulate a definition of local dependence which addresses this issue. Finally, we consider limitations of this definition and consider possibilities for its further generalisation.

Jon Erling Litland (Oslo) gives a talk at the Workshop on Groundedness (26-27 October, 2012) titled "Pure Logic of Iterated Ground". Abstract: The presently existing logics of ground have not had anything to say about iterated grounding claims, that is, claims of the form: "A grounds that (B grounds C)". I develop a pure logic of iterated ground providing a systematic account of such iterated grounding claims. The logic is developed as a Prawitz style natural deduction system; the grounding operators are provided with both introduction and elimination rules, and normalization can be proved. The resulting logic is a conservative extension of Kit Fine's Pure Logic of Ground.

Patrick Suppes (Stanford) gives a talk at the Workshop on Groundedness (26-27 October, 2012) titled "Neuroscience Perspective on the Foundations of Mathematics". Abstract: I mainly ask and partially answer three questions. First, what is a number? Second, how does the brain process numbers? Third, what are the brain processes by which mathematicians discover new theorems about numbers? Of course, these three questions generalize immediately to mathematical objects and processes of a more general nature. Typical examples are abstract groups, high dimensional spaces or probability structures. But my emphasis is not on these mathematical structures as such, but how we think about them. For the grounding of mathematics, I argue that understanding how we think about mathematics and discover new results is as important as foundations of mathematics in the traditional sense.

Brendan Balcerak Jackson (Cologne) gives a talk at the MCMP Colloquium (25 October, 2012) titled "Defusing Easy Arguments for Numbers". Abstract: Pairs of sentences like the following pose a problem for ontology:

(1) Jupiter has four moons.
(2) The number of moons of Jupiter is four.

(2) is intuitively a trivial paraphrase of (1). And yet while (1) seems ontologically innocent, (2) appears to imply the existence of numbers. Thomas Hofweber proposes that we can resolve the puzzle by recognizing that sentence (2) is syntactically derived from, and has the same meaning as, sentence (1). Despite appearances, the expressions ‘the number of moons of Jupiter’ and ‘four’ do not function semantically as singular terms in (2). Hofweber’s primary evidence for this proposal concerns differences in the focus-related communicative functions of (1) and (2). In this paper I raise several serious problems for Hofweber’s proposal, and for his attempt to support it by appeal to focus-related phenomena. I conclude by offering independent evidence for an alternative, purely pragmatic resolution of the ontological puzzle.

Elliott Sober (Wisconsin) gives a talk at the MCMP Colloquium (24 October, 2012) titled "Time and Knowability in Evolutionary Processes".

Erich Reck (UCR) gives a talk at the MCMP Colloquium (18 October, 2012) titled "Explicating Dedekind: Existential Axiomatics or Logicist Abstration?". Abstract: In recent years, there has been renewed interested in Richard Dedekind as a philosopher of mathematics, especially in connection with structuralist views about the content of mathematics. In this talk, I will juxtapose two ways of interpreting Dedekind's structuralism, or better, two explications (in Carnap's sense) of his position, that seem most promising to me. One of them is Hilbertian, leading to a reading of Dedekind as a precursor of Hilbert's "existential axiomatics"; the other is neo-Fregean or neo-logicist, in the sense of being based on a distinctive kind of "abstraction principles" that can be seen as underlying Dedekind's position. I will argue that, besides being more defensible on interpretive grounds, the second explication of Dedekind points in a direction for developing mathematical structuralism that deserves further attention today.

Ittay Nissan-Rozen (Jerusalem) gives a talk at the MCMP Formal Ethics Workshop (11-13 October, 2012) titled "Moral uncertainty and normative requirements of indifference".

Constanze Binder (Rotterdam) gives a talk at the MCMP Formal Ethics Workshop (11-13 October, 2012) titled "Social Choice and Comparative Justice: Correcting for Parochial Values".

Justin P. Bruner (UCI) gives a talk at the MCMP Formal Ethics Workshop (11-13 October, 2012) titled "Diversity, Tolerance and the Social Contract".

Elliott Wagner (Amsterdam) gives a talk at the MCMP Formal Ethics Workshop (11-13 October, 2012) titled "The long-run stability of collective action".

Conrad Heilmann (Rotterdam) gives a talk at the MCMP Formal Ethics Workshop (11-13 October, 2012) titled "Weighting Value".

Simon Huttegger (UCI) gives a talk at the MCMP Formal Ethics Workshop (11-13 October, 2012) titled "The Evolution of Norms in Structured Populations".

Shyam Nair (USC) gives a talk at the MCMP Formal Ethics Workshop (11-13 October, 2012) titled "Consequences of Reasoning with Conflicting Obligations".

Felix Pinkert (St Andrews) gives a talk at the MCMP Formal Ethics Workshop (11-13 October, 2012) titled "Inductive Proofs for Many-Hands Cases in Ethics ".

Gillman Payette (Calgary) gives a talk at the MCMP Formal Ethics Workshop (11-13 October, 2012) titled "Normative Consistency: an (X)stit account".

Campbell Brown (Edinburgh) gives a talk at the MCMP Formal Ethics Workshop (11-13 October, 2012) titled "Minding the Is-Ought Gap".

Gerhard Schurz (Düsseldorf) gives a talk at the MCMP Formal Ethics Workshop (11-13 October, 2012) titled "Formal Versions of Hume's Is-Ought Thesis".

Mathieu Beirlaen (Ghent) gives a talk at the MCMP Formal Ethics Workshop (11-13 October, 2012) titled "Dynamic Proof Theories for Reasoning with (Conditional) Norms".

Hlynur Orri Stefansson (LSE) gives a talk at the MCMP Formal Ethics Workshop (11-13 October, 2012) titled "Fairness and Counterfactuals".

Ralf M. Bader (Oxford) gives a talk at the MCMP Formal Ethics Workshop (11-13 October, 2012) titled "Separability and admissible factorisations".

Nathan Robert Howard (Toronto) gives a talk at the MCMP Formal Ethics Workshop (11-13 October, 2012) titled "The Good Samaritan Paradox".

Gert-Jan C. Lokhorst (Delft) gives a talk at the MCMP Formal Ethics Workshop (11-13 October, 2012) titled "Mally's Deontic Logic (1926)".

Paul McNamara (New Hampshire) gives a talk at the MCMP Formal Ethics Workshop (11-13 October, 2012) titled "Toward a Formal Framework for Some Fundamental Common Moral Statuses".

John Horty (University of Maryland) gives a talk at the MCMP Formal Ethics Workshop (11-13 October, 2012) titled "Common Law Reasoning".

Keith Simmons (UNC) gives a talk at the MCMP conference on Paradox and Logical Revision (July 23-25, 2012) titled "Paradox and Revenge".

Branden Fitelson (Rutgers/MCMP) gives a talk at the MCMP conference on Paradox and Logical Revision (July 23-25, 2012) titled "Paradoxes of Consistency & (Revising) The Logic of Belief".

Corine Besson (Birkbeck) gives a talk at the MCMP conference on Paradox and Logical Revision (July 23-25, 2012) titled "Some remarks about logical truth".

Mark Jago (Nottingham) gives a talk at the MCMP conference on Paradox and Logical Revision (July 23-25, 2012) titled "Revisionary Metaphysics Without Logical Revision?".

Alan Weir (Glasgow) gives a talk at the MCMP conference on Paradox and Logical Revision (July 23-25, 2012) titled "Naive Set Theory and Non-Transitive Logic".

Stewart Shapiro (Ohio State/St Andrews) gives a talk at the MCMP conference on Paradox and Logical Revision (July 23-25, 2012) titled "Revising logic in light of paradox".

Giulia Terzian (Bristol) gives a talk at the MCMP conference on Paradox and Logical Revision (July 23-25, 2012) titled "Norms of truth and logical revision".

Graham Priest (Melbourne/St Andrews/CUNY) gives a talk at the MCMP conference on Paradox and Logical Revision (July 23-25, 2012) titled "Revising Logic".

Stephen Read (St Andrews) gives a talk at the MCMP conference on Paradox and Logical Revision (July 23-25, 2012) titled "Saving Logic from Paradox".

Timothy Williamson (Oxford) gives a talk at the MCMP conference on Paradox and Logical Revision (July 23-25, 2012) titled "Logical Revision and Scientific Methodology".

David Ripley (Melbourne) gives a talk at the MCMP conference on Paradox and Logical Revision (July 23-25, 2012) titled "Anything Goes".

Elia Zardini (Aberdeen) gives a talk at the MCMP conference on Paradox and Logical Revision (July 23-25, 2012) titled "Getting One for Two, or the Contractor's Bad Deal. Towards a Unified Solution to the Semantic Paradoxes".

Zach Weber (Otago) gives a talk at the MCMP conference on Paradox and Logical Revision (July 23-25, 2012) titled "Contraction and Naive Validity".

Yannis Stephanou (Athens) gives a talk at the MCMP conference on Paradox and Logical Revision (July 23-25, 2012) titled "Logic and the Liar".

Michael Glanzberg (NU) gives a talk at the MCMP conference on Paradox and Logical Revision (July 23-25, 2012) titled "Syntax and Logical Revision".

Branden Fitelson (Rutgers) and Richard Pettigrew (Bristol) discuss philosophical approaches to coherence, differing perspectives, and formal/conceptual common grounds in part 2 ("Truth Table") of the MCMP Round Table on Coherence (20 July, 2012). Abstract: Recent arguments for probabilistic norms have attempted to justify coherence requirements for (sets of) degrees of confidence solely by appeal to considerations involving their accuracy. Richard Pettigrew, Bristol, and Branden Fitelson, Rutgers, (and their collaborators) have worked extensively on various arguments of this sort. This public MCMP event is to bring their differing approaches and perspectives to one table.

Branden Fitelson (Rutgers) and Richard Pettigrew (Bristol) present formal approaches to coherence in part 1 ("Table of Contents") of the MCMP Round Table on Coherence (20 July, 2012). Abstract: Recent arguments for probabilistic norms have attempted to justify coherence requirements for (sets of) degrees of confidence solely by appeal to considerations involving their accuracy. Richard Pettigrew, Bristol, and Branden Fitelson, Rutgers, (and their collaborators) have worked extensively on various arguments of this sort. This public MCMP event is to bring their differing approaches and perspectives to one table.

Kevin Sharp (The Ohio State University) gives a talk at the MCMP Colloquium (12 July 2012) about the aletheic paradoxes and semantic relativism. Abstract: I propose a solution to the aletheic paradoxes (e.g., the liar, Curry, and Yablo) on which truth predicates are assessment-sensitive. Truth is not an antecedently plausible topic for a semantic relativist treatment; nevertheless, the aletheic paradoxes give us good reason to think that truth is an inconsistent concept, and there are good reasons to think that semantic relativism is appropriate for inconsistent concepts. Thus, I show that a promising version of the best approach to the paradoxes is an application of semantic relativism to truth itself — arguing from results about the paradoxes and general considerations about language use to aletheic assessment-sensitivity. The first part of the talk focuses on replacing our inconsistent concept of truth, and the second on assessment-sensitivity with respect to truth predicates. The first contains an overview of my preferred approach to the paradoxes, which entails that truth is an inconsistent concept and should be replaced (for certain purposes) by a team of consistent concepts that can do its work without causing troubling paradoxes. The second part considers which treatment is most appropriate for our inconsistent concept of truth. In it, I propose an assessment-sensitivity view of truth, discuss some prominent objections to semantic relativism, and review some issues that arise for approaches to the aletheic paradoxes.

Joe Halpern (Cornell University) gives a talk at the MCMP Colloquium (11 July, 2012) titled "Constructive Decision Theory" (joint work with Larry Blume and David Easley, Cornell). Abstract: The standard approach in decision theory (going back to Savage) is to place a preference order on acts, where an act is a function from states to outcomes. If the preference order satisfies appropriate postulates, then the decision maker can be viewed as acting as if he has a probability on states and a utility function on outcomes, and is maximizing expected utility. This framework implicitly assumes that the decision maker knows what the states and outcomes are. That isn't reasonable in a complex situation. For example, in trying to decide whether or not to attack Iraq, what are the states and what are the outcomes? We redo Savage viewing acts essentially as syntactic programs. We don't need to assume either states or outcomes. However, among other things, we can get representation theorems in the spirit of Savage's theorems; for Savage, the agent's probability and utility are subjective; for us, in addition to the probability and utility being subjective, so is the state space and the outcome space. I discuss the benefits, both conceptual and pragmatic, of this approach. As I show, among other things, it provides an elegant solution to framing problems. This is joint work with Larry Blume and David Easley. No prior knowledge of Savage's work is assumed.

Robert Sugden (UEA) gives a talk at the MCMP Colloquium (5 July, 2012) titled "How the market gives us what we want - even if we are irrational".

Conrad Heilmann (Rotterdam) gives a talk at the MCMP Colloquium (4 July, 2012) titled "Weighting Evaluations". Abstract: This paper discusses two approaches to weighting numerical evaluations. We start by assuming that we have obtained numerical evaluations of some type of object, such as a utility function that represents preferences over acts. We then ask how we can weight these evaluations and identify two approaches. One approach, called the probability approach, derives a separate measure on the domain of objects on which the value operation was defined. The other approach, called the discounting approach, enriches the description of the domain so as to amend the value operation directly, which yields an implied measure. We analyse and compare the two approaches along four lines, asking how they (i) can be motivated conceptually, (ii) derive and elicit the measures, (iii) can apply the respective measures, and (iv) update the measures. The upshot of this discussion is that the probability approach should be favoured over the discounting approach on all four accounts.

Conor Mayo-Wilson (CMU) gives a talk at the Sixth Workshop in Decisions, Games & Logic '12 (June 28-30, 2012) titled "The Reliability of Testimonial Norms in Academic Communities".

Emmanuel Genot (Lund) gives a talk at the Sixth Workshop in Decisions, Games & Logic '12 (June 28-30, 2012) titled "Semantic Games for Algorithmic Players" (joint work with Justine Jacot).

Sonja Smets (ILLC/Amsterdam) gives part II of her tutorial in logic (30 June 2012) titled "Recent topics in Dynamic Epistemic Logic".

Sonja Smets (ILLC/Amsterdam) gives part I of her tutorial in logic (30 June 2012) titled "Recent topics in Dynamic Epistemic Logic".

Erik Mohlin (UCL) gives a talk at the Sixth Workshop in Decisions, Games & Logic '12 (June 28-30, 2012) titled "Optimal Categorization".

Christian W. Bach (Maastricht) gives a talk at the Sixth Workshop in Decisions, Games & Logic '12 (June 28-30, 2012) titled "Pairwise Interactive Knowledge and Nash Equilibrium" (joint work with Elias Tsakas).

Hlynur Orri Stefánsson (LSE) gives a talk at the Sixth Workshop in Decisions, Games & Logic '12 (June 28-30, 2012) titled "Desirability of Conditionals".

Conrad Heilmann (Rotterdam) gives a talk at the Sixth Workshop in Decisions, Games & Logic '12 (June 28-30, 2012) titled "Exponential Discounting for Changing Preferences".

Wulf Gaertner (Osnabrück) gives a talk at the Sixth Workshop in Decisions, Games & Logic '12 (June 28-30, 2012) titled "A General Scoring Rule".

Richard Pettigrew (Bristol) gives part II of his tutorial in decision theory (28 June 2012) titled "Conditionalization".

Richard Pettigrew (Bristol) gives part I of his tutorial in decision theory (28 June 2012) titled "Decision theory in epistemology".

Richard Bradley (LSE) gives a talk at the MCMP Colloquium (27 June, 2012) titled "Bayesian Conditioning Revisited". Abstract: Bayesian conditioning is widely regarded as the correct way to revise your degrees of belief in circumstances in which experience leads you to believe, with certainty, that some proposition is true. But different revision rules have been proposed for other types of experience: for example, Jeffrey conditioning when your degrees of belief for some set of propositions changes without your becoming certain of any of them; or Adams conditioning, when you conditional degrees of belief change. In this talk I will argue that these rules are all characterised by two properties - Responsiveness to experience and Conservativeness (in the sense of conserving any beliefs on matters on which experience is silent) - and that what distinguishes them is just the nature of the experiences to which they respond. Furthermore they are the only rules with these properties defined on these experiences.

Paul E. Oppenheimer (Stanford) gives a talk at the MCMP Colloquium (21 June, 2012) titled "Representation and Interpretation in Computational Philosophy".

David Miller (Warwick) gives a talk at the MCMP Colloquium (21 June, 2012) titled "If You Must Do Confirmation Theory - Do It This Way". Abstract: In this talk I begin to draw together, and package into a coherent philosophical position, a number of ideas that in the last 25 years I have alluded to, or sometimes stated explicitly, concerning the properties and the merits of the measure of deductive dependence q(c|a) of one proposition c on another proposition a; that is, the measure to which the (deductive) content of c is included within the content of a.

Charles B. Cross (University of Georgia) gives a talk at the MCMP Colloquium (20 June, 2012) titled "A Copernican Revolution for Modal Fictionalism". Abstract: According to Modal Fictionalism, the analysans in the possible-worlds analysis of a modal claim should be understood as occurring within the scope of a (normally untokened) story operator or prefix. Placing a piece of discourse behind a story prefix, on this view, cancels any commitment to the existence of items postulated by the "story". Modal Fictionalism faces persistent objections, however, and I argue that the best option in the face of these objections is a revolutionary reformulation. Given this reformulation, the usual objections to Modal Fictionalism simply vanish.

Natalie Gold (King's College London) gives a talk at the MCMP Colloquium (11 July, 2012) titled "Moral Judgments and Decisions in Trolley Problems". Abstract: Hypothetical dilemmas, such as trolley problems, are used by philosophers and psychologists in order to probe intuitions about whether it is morally permissible to harm one person in order to prevent a greater harm to others. The dilemmas usually involve life and death decisions. I report the results of an experiment using hypothetical dilemmas in which the domain and severity of harm are varied and an experiment using a real life trolley problem, involving economic harms.

Steve Awodey (CMU/MCMP) gives a talk at the MCMP Colloquium (13 June, 2012) titled "Homotopy Type Theory and Univalent Foundations of Mathematics". Abstract: Recent advances in foundations of mathematics have led to some developments that are significant for the philosophy of mathematics, particularly structuralism. The discovery of an interpretation of constructive type theory into homotopy theory suggests a new approach to the foundations of mathematics with both intrinsic geometric content and a computational implementation. In this setting, leading homotopy theorist Vladimir Voevodsky has proposed new axiom for foundations with both geometric and logical significance: the Univalence Axiom. It captures the familiar aspect of informal mathematical practice, according to which one can identify isomorphic objects. While it is incompatible with conventional foundations, it is a powerful addition to homotopy type theory, and forms the basis of the new Univalent Foundations Program.

Paul Schweizer (Edinburgh) gives a talk at the MCMP Colloquium (11 July, 2012) titled "Multiple Realization and the Computational Mind". Abstract: The paper addresses a standard line of criticism of the Computational Theory of Mind, based on the claim that realizing a computational formalism is overly liberal to the point of vacuity. In agreement with the underlying view of computation used to support this criticism, I argue that computation is not an intrinsic property of physical systems, but rather requires an observer dependent act of interpretation. The extent to which a given configuration of matter and energy can be said to realize an abstract formalism is always a matter of approximation and degree, and interpreting a physical device as performing a computation is relative to our purposes and potential epistemic gains. And while this may fatally undermine a computational explanation of consciousness, I argue that, contra Putnam and Searle, it does not rule out the possibility of a scientifically defensible account of propositional attitude states in computational terms.

Eric Pacuit (University of Maryland) gives a talk at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012) titled "First-Order Extensions of Classical Modal Logic". Abstract: The paper focuses on extending to the first order case the semantical program for modalities first introduced by Dana Scott and Richard Montague. We focus on the study of neighborhood frames with constant domains and we offer a series of new completeness results for salient classical systems of first order modal logic. Among other results we show that it is possible to prove strong completeness results for normal systems without the Barcan Formula (like FOL+K) in terms of neighborhood frames with constant domains. The first order models we present permit the study of many epistemic modalities recently proposed in computer science as well as the development of adequate models for monadic operators of high probability. Models of this type are either difficult of impossible to build in terms of relational Kripkean semantics. We conclude by introducing general first order neighborhood frames and we offer a general completeness result in terms of them which circumvents some well-known problems of propositional and first order neighborhood semantics (mainly the fact that many classical modal logics are incomplete with respect to an unmodified version of neighborhood frames). We argue that the semantical program that thus arises surpasses both in expressivity and adequacy the standard Kripkean approach, even when it comes to the study of first order normal systems.

Matthew Kotzen (UNC) comments on Julia Staffel's "Should I Pretend I'm Perfect?" at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012).

Julia Staffel (USC) gives a talk at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012) titled "Should I pretend I'm perfect?".

Arthur Paul Pedersen (CMU) gives a talk at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012) titled "The Theory of Probability Cores in Bayesian Epistemology and Decision Theory".

Mike Titelbaum (University of Wisconsin) comments on Wolfgang Schwarz's "Lost Memories and Useless Coins" at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012).

Wolfgang Schwarz (ANU) gives a talk at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012) titled "Lost memories and useless coins: Revisiting the absentminded driver".

Rohit Parikh (CUNY) gives a talk at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012) titled "Influencing Behavior by Influencing Knowledge".

David Etlin (Groningen) comments on Hans Rott's "Two concepts of plausibility in default reasoning" at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012).

Hans Rott (Regensburg) gives a talk at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012) titled "Two concepts of plausibility in default reasoning".

Gila Sher (UCSD) gives a talk at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012) titled "Logic & Rationality".

Jeff Paris (Manchester) gives the second part of his tutorial "Inductive Logic" at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012).

Mark Colyvan (Sidney) comments on Michael Morreau's "From Social Choice to Theory Choice" at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012).

Michael Morreau (University of Maryland) gives a talk at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012) titled "From Social Choice to Theory Choice". Abstract: Arrow's theorem of social choice (Arrow 1951) has been thought to limit the possibilities for choosing rationally among rival scientific theories on the basis of their accuracy, simplicity, scope and other relevant criteria. It does not. Possible orderings of theories by these criteria are so severely restricted that the theorem is irrelevant in this connection. On the contrary, what is known about social choice in restricted domains implies that there are many acceptable procedures for choosing among theories on the basis of their various merits and demerits.

Wlodek Rabinowicz (Lund) gives a talk at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012) titled "Aggregating value judgments" (joint work with Stephan Hartmann and Soroush Rafiee Rad).

Rachael Briggs (ANU) comments on Mark Jago's "Bounded Rationality and Epistemic Blindspots" at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012).

Abstract: Real-world agents do not know all consequences of what they know. But we are reluctant to say that a rational agent can fail to know some trivial consequence of what she knows. Since every consequence of what she knows can be reached via chains of trivial consequences of what she knows, we have a paradox. In this paper, I respond to the paradox in three stages. (i) I describe formal models which allow us to draw a distinction, at the level of content, between trivial (uninformative) and non-trivial (informative) inferences. (ii) I argue that agents can fail to know trivial consequences of what they know, but they can never do so determinately. Such cases are epistemic blindspots, and we are never in a position to assert that such-and-such constitutes a blindspot for agent i. (iii) I develop formal epistemic models on which the epistemic accessibility relations are vague. Given these models, we can show that epistemic blindspots always concern indeterminate cases of knowledge.

Catarina Dutilh Novaes (Groningen) gives a talk at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012) titled "A dialogical, multi-agent account of the normativity of logic".

Jeff Paris (Manchester) gives the first part of his tutorial "Inductive Logic" at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012).

Thomas Hofweber (UNC) comments on Alan Hájek's "Staying Regular?" at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012).

Alan Hájek (ANU) gives a talk at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012) titled "Staying Regular?".

Chris Meacham (University of Massachusetts) comments on Ben Levinstein's "Leitgeb and Pettigrew on Accuracy and Updating" at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012).

Ben Levinstein (Rutgers) gives a talk at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012) titled "Leitgeb and Pettigrew on Accuracy and Updating". Abstract: Leitgeb and Pettigrew (2010) argue that (1) agents should minimize the expected inaccuracy of their beliefs, and (2) inaccuracy should be measured via the Brier score. They show that in certain diachronic cases, these claims require an alternative to Jeffrey-Conditionalization. I claim that this alternative is an irrational updating procedure and that the Brier score, and quadratic scoring rules generally, should be rejected as legitimate measures of inaccuracy.

Sylvia Wenmackers (Groningen) gives the second part of her tutorial "Hyperreals and Their Applications" at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012). Abstract: Hyperreal numbers are an extension of the real numbers, which contain infinitesimals and infinite numbers. The set of hyperreal numbers is denoted by *R or R*; in these notes, I opt for the former notation, as it allows us to read the *-symbol as the prefix 'hyper-'. Just like standard analysis (or calculus) is the theory of the real numbers, non-standard analysis (NSA) is the theory of the hyperreal numbers. NSA was developed by Robinson in the 1960’s and can be regarded as giving rigorous foundations for intuitions about infinitesimals that go back to Leibniz (at least).
In section 4, we give an overview of the areas of applications of NSA. We return to a selection of them in the subsequent sections. Section 5: history of the calculus; section 6: intuitions about infinitesimals; section 7: paradoxes of infinity; section 8: probability and formal epistemology; and section 9: physics and philosophy of science.

Frederik Herzberg (Bielefeld, MCMP/LMU) comments on "The No Alternatives Argument" (by Richard Dawid, Stephan Hartmann, and Jan Sprenger) at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012).

Jan Sprenger (Tilburg) gives a talk at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012) titled "The No Alternatives Argument" (joint work with Richard Dawid and Stephan Hartmann). Abstract: Scientific theories are hard to find, and once scientists have found a theory H, they often believe that there cannot be many distinct alternatives to H. But is this belief justied? What should scientists believe about the number of alternatives to H, and how should they change these beliefs in the light of new evidence? These are some of the questions that we will address in this paper. We also ask under which conditions failure to find an alternative to H confirms the theory in question. This kind of reasoning (which we call the no alternatives argument) is rather popular in science and therefore deserves a careful philosophical analysis.

Brad Armendt (ASU) comments on Lara Buchak's "Risk and Tradeoffs" at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012).

Lara Buchak (Berkeley) gives a talk at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012) titled "Risk and Tradeoffs".

David Christensen (Brown University) gives a talk at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012) titled "Epistemic Modesty Defended".

Sylvia Wenmackers (Groningen) gives the first part of her tutorial "Hyperreals and Their Applications" at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012). Abstract: Hyperreal numbers are an extension of the real numbers, which contain infinitesimals and infinite numbers. The set of hyperreal numbers is denoted by *R or R*; in these notes, I opt for the former notation, as it allows us to read the *-symbol as the prefix 'hyper-'. Just like standard analysis (or calculus) is the theory of the real numbers, non-standard analysis (NSA) is the theory of the hyperreal numbers. NSA was developed by Robinson in the 1960’s and can be regarded as giving rigorous foundations for intuitions about infinitesimals that go back to Leibniz (at least).
NSA can be introduced in multiple ways. Instead of choosing one option, these notes include three introductions. Section 1 is best-suited for those who are familiar with logic, or who want to get a flavor of model theory. Section 2 focuses on some common ingredients of various axiomatic approaches to NSA, including the star-map and the Transfer principle. Section 3 explains the ultrapower construction of the hyperreals; it also includes an explanation of the notion of a free ultrafilter.

Jim Joyce (University of Michigan) comments on Richard Pettigrew's "What chance-credence norms should not be" at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012).

Richard Pettigrew (Bristol) gives a talk at the 9th Formal Epistemology Workshop (Munich, May 29–June 2, 2012) titled "What chance-credence norms should not be".

Roberto Ciuni (RUB) gives a talk at the MCMP Colloquium (24 May, 2012) titled "Ought Implies Can, Omission and Probabilistic Deliberative STIT". Abstract: STIT logics are prominent formal settings for modelling the interaction among agents. Remarkably, they endorse some basic game-theoretical notion, most notably alpha-effectivity: the moves of one agent are independent from the ones of any other agent. This is in turn reflected in the semantics of the deliberative stit operator [a : X], which reads 'agent a ensures - in the next moment'. In the last ten years, STIT logics have been applied to a number of issues at the cross between deontic logic, ethics and legal philosophy, such as the notion of responsibility. The Principle 'Ought implies Can' (OC) is a widespread principle in ethics, which is taken to provide a criterion of fairness for establishing 'oughts'. Responsibility for omission is that kind of responsibility which holds of an agent if she did not ensure something she had the obligation of ensuring. Among the cases of omission, we have omission w.r.t. other agents' wrong-doing (not preventing others from accomplishing violations of norms). In the paper, I show that responsibility for this kind of omission (RNP) is impossible in a deontic STIT logic with the above operator and which endorses OC (the latter being a consequence of employing [a:X]). Since there are reasons for keeping STIT, OC and RNP, I explore a way to fix the problem which does not renounce to any of them: I introduce a deliberative STIT logic which is able to deal with the notions of 'attempting' and 'maximizing the chance that another agent fails'. Interestingly, this is done without renouncing to the 'Independence of Agents', which is indeed the characteristic principle of STIT logics and the responsible of traditional STIT's failure in modeling RNP.

Hans van Ditmarsch (University of Sevilla) gives a talk at the MCMP Colloquium (23 May, 2012) titled "Everything is knowable". Abstract: Dynamic epistemic logics are modal logics of knowledge (and belief) change, with modal epistemic operators to describe knowledge and dynamic modal operators to describe change of knowledge. In such a logic we can analyze the Moore-sentence, 'p is true but you don't know that p is true', and also the Fitch-paradox. 'everything is knowable' is inconsistent with 'there is an unknown truth'.
The Moore sentence becomes false as a consequence of being announced. In this sense it is an 'unsuccessful' knowledge update. 'Success' is one of the requirements in AGM belief revision.
The Fitch paradox can be analyzed in dynamic epistemic logic when we interpret 'knowable' as 'known after an announcement'. The Moore and Fitch themes are much related and hold for S5 knowledge and for KD45 (consistent) belief.
Given the interpretation of 'successful' as 'known after its announcement' 'knowable' as 'known after an announcement', successful implies knowable. But knowable does not imply successful. All propositions are knowable in a more general sense: for each proposition, we can know whether it is true: either the proposition can become known or its negation can become known. In that sense, the Moore sentence is knowable!

Thomas Forster (Cambridge) gives a talk at the MCMP Colloquium (16 May, 2012) about Quine's "New Foundations". Abstract: There are rumours circulating that Quine's axiomatic set theory "New Foundations" has been proved consistent. If these rumours are correct the set theoretic landscape will have its most radical revamp for more than half a century, and we will all need to re-tool. This talk will provide historical background and glimpse into how the result might be proved.

Jeff Barrett (UC Irvine) gives a talk at the MCMP Colloquium (10 May, 2012) titled "Modeling the Coevolution of Theory and Language". Abstract: Skyrms-Lewis sender-receiver games with invention allow one to model how a simple mathematical language might be invented and become meaningful as its use coevolves with the basic arithmetic competence of primitive mathematical inquirers. Such models provide sufficient conditions for the invention and evolution of a very basic sort of arithmetic language and practice, and, in doing so, provide insight into the nature of a correspondingly basic sort of mathematical knowledge in an evolutionary context. Given traditional philosophical reflections concerning the nature and preconditions of mathematical knowledge, these conditions are strikingly modest.

Karl-Georg Niebergall (HU Berlin) gives a talk at the MCMP Colloquium (3 May, 2012) titled "Assumptions of Infinity". Abstract: I present different attempts of explicating "theory T makes an assumption of infinity" and consider their consequences.

Lavinia Picollo (Buenos Aires) gives a talk at the MCMP Colloquium (3 May, 2012) titled "Reference and Circularity in First-Order Arithmetical Systems". Abstract:

Eduardo Alejandro Barrio (Buenos Aires) gives a talk at the MCMP Colloquium (2 May, 2012) titled "The Revision Theory of Truth (T#), FS and the Standard Model of PA".

Kristina Liefke (Tilburg) gives a talk at the MCMP Colloquium (26 April, 2012) titled "A Single-Type Semantics for Natural Language". Abstract: Richard Montague's Intensional Logic [2] constitutes a milestone in the project of providing a formal semantics for natural language. Its use enables the systematic translation of natural into formal language expressions and allows a mathematically rigorous account of a wide range of semantic phenomena. Despite its success, Montague's logic has, in the last decade, been subject to significant criticism [1, 3]. The latter pertains to the descriptive inadequacy of its underlying system of semantic domains, especially of the distinction between the interpretive domains of noun phrases (i.e. individuals) and sentences (i.e. propositions). To remedy this inadequacy, I develop a semantics for natural language that replaces individuals and propositions by a single type of object (hence 'single-type semantics'). In particular, I compare different single-type alternatives, identify the most suitable candidate, and show that it models a standard fragment of English.

Cameron Buckner (Bochum) gives a talk at the MCMP Colloquium (26 April, 2012) titled "Dynamic Ontology". Abstract: A computational ontology is a formally-encoded specification of the concepts relevant to a subject domain (including their properties and relations holding between them) and a hierarchical classification of those concepts into categories and subcategories. Such representations can support a variety of tasks and tools which require semantic knowledge of domain resources. The standard method of ontology design makes use of “double experts” — users trained in both the target domain and computational ontology design — to manually produce maximally-correct domain descriptions. Unfortunately, double-experts are expensive and prone to bias, and when domains change or evolve, ontologies must be revised manually. While perhaps appropriate for large, deep-pocketed projects working on relatively stable domains such as the natural sciences, the approach is often not feasible for smaller, open-access projects working on more dynamic domains such as the humanities. To serve these projects, we have recommended an approach we call “dynamic ontology”. In dynamic ontology, more effort is placed on automating as much of the ontology design and evolution process as possible. Forgoing the use of double experts creates its own challenges, however; dynamic ontologists must be more creative in their methods of obtaining data for ontology construction and population, and problems of data inconsistency and validation loom large. In this talk, I will describe the how these challenges are addressed in the architecture of the Indiana Philosophy Ontology project, which uses a three-step process of statistical information retrieval, targeted solicitation of expert feedback, and machine reasoning to assemble a dynamic knowledge base for the discipline of philosophy.

Wlodek Rabinowicz (Lund) gives a talk at the MCMP colloquium (24 April, 2012) titled "Value Relations Revisited". Abstract: In Rabinowicz 2008, I considered how value relations can best be analyzed in terms of fitting pro-attitudes. In the formal model of that paper, fitting pro-attitudes were represented by the class of permissible preference orderings on a domain of items that are being compared. As it turns out, this approach opens up for a multiplicity of different types of value relationships, along with the standard relations of "better", "worse", "equally as good as" and "incomparable in value". Unfortunately, though, the approach is vulnerable to a number of objections.
 These objections can be avoided if one re-interprets the underlying notion of preference: Instead of treating preference as a 'dyadic' attitude directed towards a pair of items, we can think of it as a difference in degree between 'monadic' attitudes of favouring. Each such monadic attitude has just one item as its object. Given this re-interpretation, permissible preferences can be modelled by the class of permissible assignments of degrees of favouring to items in the domain. From this construction, we can then recover the old modelling in terms of the class of permissible preference orderings, but the previous objections to that model no longer apply.

Jaroslav Peregrin (Czechoslovak Academy of Sciences) gives a talk at the MCMP Colloquium (19 April, 2012) titled "Logic and reasoning". Abstract: Logic, it is often held, is primarily concerned with reasoning; and the conviction that logic and reasoning are two sides of the same coin nowadays usually equates with the conviction that logic spells out some directives for the "right" management of beliefs. In this talk I put forward an alternative view, based on seeing rules of logic rules as constitutive rules, not instructing us *how* to reason, but rather providing us with certain vehicles or *in terms of which* to reason. This also emphasizes the social nature of beliefs: they are entities forged in a social mold, formed by rules originating from social argumentative practices. Because of this fact, I suggest, trying to understand logic by means of studying (rules of) the kinematics of beliefs of a solitary individual is essentially misguided.

Martin Kusch (Vienna) gives a talk at the MCMP Colloquium (18 April, 2012) titled "Wittgenstein and the Epistemology of Peer Disagreement". Abstract: This paper seeks to reconstruct Wittgenstein's views on the epistemology of peer disagreement, and especially in the realm of religious disagreement. I use recent work by Feldman, Sosa, Lackey and others as foils. I seek to show that Wittgenstein leans towards a relativistic conception of such disagreements.

Greg Restall (Melbourne) gives a talk at the MCMP Colloquium (18 April, 2012) titled "Assertion, Denial and the Logic of Definedness".

Greg Restall (Melbourne) gives a talk at the MCMP Colloquium (12 Apr, 2012) titled "Sequent Systems and Defining Rules". Abstract: In this talk I will explain how it can be that inference rules can be used to define a class of concepts, and why there are at least three grades of logical complexity (propositional connectives, quantifiers, and modals), depending on the kinds of discourse features exploited in those rules. I'll then explain how concepts characterised by "defining rules" (which I’ll precisely characterise) have a number of important features, such as admitting a uniform cut elimination argument.

Wilfrid Hodges (School of Mathematical Sciences) gives a talk at the MCMP Colloquium (21 Mar, 2012) titled "What would count as Ibn Sina (11th c. Persia) having first order logic?". Abstract: People debate whether first order logic was invented in 1879, or 1885, or 1928. I will push the boat out much further and discuss the case for around 1025. The question is methodological as much as historical. We have masses of evidence about what Ibn Sina did or didn't know in logic. But his notion of what logic does was so different from ours that there is no straightforward answer to the question 'Did he know first order logic?'. I will give the case for the answer Yes and the case for the answer No.

Michael Glanzberg (Northwestern University) gives a talk at the Axiomatic versus Semantic Truth Conference (14-16 March, 2012) titled "Semantic Truth and the Correspondence Theory".

Toby Meadows (Arché Research Centre) gives a talk at the Axiomatic vs Semantic Truth Conference (14-16 March, 2012) titled "Let Three Flowers Bloom".

Jeffrey Ketland (MCMP/LMU) gives a talk at the Axiomatic versus Semantic Truth Conference (14-16 March, 2012) titled "Deflationism vs Representationalism".

Andrea Cantini (Florence) gives a talk at the Axiomatic versus Semantic Truth Conference (14-16 March, 2012) titled "Stratified Truth?".

Carlo Nicolai (Oxford) gives a talk at the Axiomatic versus Semantic Truth Conference (14-16 March, 2012) titled "Truth, Syntax, Conservativity".

Theodora Achourioti (ILLC) gives a talk at the Axiomatic versus Semantic Truth Conference (14-16 March, 2012) titled "Modelling the use of 'true' in natural Language".

Jc Beall (Connecticut, Otago) gives a talk at the Axiomatic versus Semantic Truth Conference (14-16 March, 2012) titled "Truth Without Detachment".

Andrew Bacon (Oxford) gives a talk at the Axiomatic versus Semantic Truth Conference (14-16 March, 2012) titled "A general approach to revenge paradoxes".

Luca Incurvati (Magdalene College Cambridge) gives a talk at the Axiomatic versus Semantic Truth Conference (14-16 March, 2012) titled "A Conception of Set-Theoretical Truth".

Volker Halbach (Oxford) gives a talk at the Axiomatic versus Semantic Truth Conference (14-16 March, 2012) titled "Axiomatic and Semantic Theories of Truth".

Christopher Gauker (Cincinnati) gives a talk at the MCMP Colloquium (9 Feb, 2012) titled "Validity without Reference". Abstract: Two definitions of logical validity for a simple first-order language will be compared in order to decide which one provides a better model for the semantics for natural language. One of these is the standard model-theoretic definition. The other defines contexts as structures of linguistic objects and then defines validity as preservation of truth-in-a-context. The disadvantage of the model-theoretic definition is that it commits us to explicating the reference relation, which no one has ever been able to do. The context-logical definition avoids this commitment, although it takes on others. It particular, it commits to explaining what it takes for a given context to be the context that pertains to a conversation. As a three-valued theory, the context-logical definition generates a non-classical logic; this consequence will be defended. Inasmuch as it employs a substitutional interpretation of quantifiers, the context-logical definition faces a technical problem having to do with the omega rule. This will be addressed by arguing that even for purposes of defining logical validity, natural languages may be individuated in such a way as to contain no fixed number of singular terms.

Peter Verdée (Ghent) gives a talk at the MCMP Colloquium (8 Feb, 2012) titled "Adaptive Logics: Introduction, Applications, Computational Aspects and Recent Developments". Abstract: Peter Verd ́ee (peter.verdee@ugent.be) Centre for Logic and Philosophy of Science Ghent University, Belgium In this talk I give a thorough introduction to adaptive logics (cf. [1, 2, 3]). Adaptive logics are first devised by Diderik Batens and are now the main research area of the logicians in the Centre for Logic and Philosophy of Science in Ghent. First I explain the main purpose of adaptive logics: formalizing defea- sible reasoning in a unified way aiming at a normative account of fallible rationality. I give an informal characterization of what we mean by the notion ‘defeasible reasoning’ and explain why it is useful and interesting to formalize this type of reasoning by means of logics. Then I present the technical machinery of the so called standard format of adaptive logics. The standard format is a general way to define adaptive logics from three basic variables. Most existing adaptive logics can be defined within this format. It immediately provides the logics with a dynamic proof theory, a selection semantics and a number of important meta-theoretic properties. I proceed by giving some popular concrete examples of adaptive logics in standard form. I quickly introduce inconsistency adaptive logics, adap- tive logics for induction and adaptive logics for reasoning with plausible knowledge/beliefs.
Next I present some computational results on adaptive logics. The adap- tive consequence relation are in general rather complex (I proved that there are recursive premise sets such that their adaptive consequence sets are Π1- complex – cf. [4]). However, I argue that this does not harm the naturalistic aims of adaptive logics, given a specific view on the relation between actual reasoning and adaptive logics. Finally, two interesting recent developments are presented: (1) Lexi- cographic adaptive logics. They fall outside of the scope of the standard format, but have similar properties and are able to handle prioritized infor- mation. (2) Adaptive set theories. Such theories start form the unrestricted comprehension axiom scheme but are strong enough to serve as a foundation for an interesting part of classical mathematics, by treating the paradoxes in a novel, defeasible way.

Valentin Sorin Costreie (Bucharest) gives a talk at the MCMP Colloquium (9 Feb, 2012) titled "Mathematical cognition and mathematical structuralism". Abstract: Recent studies concerning mathematical cognition show that we may find mathematical cognitive capacities in young infants and monkeys. They show that we possess an innate intuition of small natural integers around the age of six month, and thus they are commonly interpreted in the sense of providing new grounds for a revival of Kantian intuitionism. Yet, if we speak of intuitions, they are intuitions of what? So, the target of my study will be to clarify the role played by intuitions in mathematical cognition, trying to better see the connection between mathematical cognition, intuitionism and structuralism.

Kevin Kelly (CMU Pittsburgh), Hanti Lin (CMU Pittsburgh), and Hannes Leitgeb (LMU/MCMP) discuss philosophical theories of acceptance, belief revision, and formal/conceptual common grounds in part 2 ("Truth Table") of the Round Table on Acceptance (3 Feb, 2012). Abstract: The Bayesianist concept of belief is described by a measure-theoretic and thus quantitative approach to probabilities as changeable degrees of belief, whereas classical epistemology views belief/acceptance as a qualitative notion.

Questions arise from this contrast: How can the two concepts be related? Which bridge principles can be drawn on to accomplish this task?

This public MCMP event is to bring the philosophical theories of Leitgeb and Kelly/Lin to one table.

Kevin Kelly (CMU Pittsburgh), Hanti Lin (CMU Pittsburgh), and Hannes Leitgeb (LMU/MCMP) present formal theories of acceptance and their application in part 1 ("Table of Contents") of the Round Table on Acceptance (3 Feb, 2012). Abstract: The Bayesianist concept of belief is described by a measure-theoretic and thus quantitative approach to probabilities as changeable degrees of belief, whereas classical epistemology views belief/acceptance as a qualitative notion.

Questions arise from this contrast: How can the two concepts be related? Which bridge principles can be drawn on to accomplish this task?

This public MCMP event is to bring the philosophical theories of Leitgeb and Kelly/Lin to one table.

Stephen Read (St. Andrews) gives a talk at the MCMP Colloquium (2 Feb, 2012) titled "General-Elimination Harmony". Abstract: Michael Dummett introduced the notion of harmony in response to Arthur Prior's tonkish attack on the idea of proof-theoretic justification of logical laws (or analytic validity). But Dummett vacillated between different conceptions of harmony, in an attempt to use the idea to underpin his anti-realism. Dag Prawitz had already articulated an idea of Gerhard Gentzen's into a procedure whereby elimination-rules are in some sense functions of the corresponding introduction-rules. The corresponding conception of general-elimination harmony ensures that the introduction-rules are transparent in the meaning they confer, in that the elimination-rules match the meaning the introduction-rules confer exactly.

Leonard A. Smith (LSE) gives a talk at the Rationality & Decision Meeting Munich (26-28 Jan, 2012) titled "Does Radical Uncertainty Require Regime Change?".

Jon Williamson (Kent) gives a talk at the Rationality & Decision Meeting Munich (26-28 Jan, 2012) titled "How uncertain do we need to be?".

Sonja Smets (ILLC Amsterdam) gives a talk at the Rationality & Decision Meeting Munich (26-28 Jan, 2012) titled "Logics for 'Soft' Interactive Epistemology".

Barteld Kooi (Groningen) gives a talk at the Rationality & Decision Meeting Munich (26-28 Jan, 2012) titled "Dynamic Logic of Reasoning".

Jake Chandler (Katholieke Universiteit Leuven) gives a talk at the Rationality & Decision Meeting Munich (26-28 Jan, 2012) titled "Subjective probabilities need not be sharp".

Luc Bovens (LSE) gives a talk at the Rationality & Decision Meeting Munich (26-28 Jan, 2012) titled "Ordering Risky Prospects - Prioritarianism: an Ecumenical Approach".

Kai Spiekermann (LSE) gives a talk at the Rationality & Decision Meeting Munich (26-28 Jan, 2012) titled "The Precautionary Principle Reconceptualized".

Matthias Schirn (LMU) gives a talk at the MCMP Colloquium (26 Jan, 2012) titled "Logical abstractions and logical objects in Frege: a critical approach". Abstract: In this talk, I shall critically discuss some key issues related to Frege’s notion of logical object, his paradigms of second-order abstraction principles (Hume’s Principle and Axiom V; see my handout), his logicism and, if time allows, the position which has come to be known as neo-logicism. Although the notion of logical object plays a key role in Frege’s foundational project, it has hardly been analyzed in depth so far. I shall begin by explaining the connection between logical abstraction and logical objects. A schema for a Fregean abstraction principle can be stated as follows: Q(a) = Q(b) « Req(a, b). Here “Q” is a singular term-forming operator,a and b are free variables of the appropriate type, ranging over the members of a given domain, and “Req” is the sign for an equivalence relation holding between the values of a and b. I call an abstraction principle logical if the equivalence relation, denoted on its right-hand side, can be defined in second-order or higher-order logic. I shall argue that Frege’s principal motive for introducing extensions of concepts into his logical theory is not to be able to make indirect statements about concepts, but rather to define all numbers as logical objects of a fundamental and an irreducible kind in order to ensure that we have the right cognitive access to them qua logical objects via Axiom V. Nonetheless, reducibility to extensions cannot be the ultimate criterion for Frege of what is to be regarded as a logical object. In the second part, I shall briefly examine Frege’s problem of ref erential indeterminacy of numerical singular terms in The Foundations of Arithmetic (1884) and of course-of-values terms in his opus magnum The Basic Laws of Arithmetic (vol. I, 1893/vol II, 1903). This problem arises from what is usually called “the Julius Caesar problem”. In The Foundations, Frege attempted to introduce cardinal numbers as logical objects by means of Hume’s Principle (after having explored an unsuccessful inductive definition). The attempt miscarried, because in its role as a contextual definition Hume’s Principle fails to fix uniquely the reference of the cardinality operator “the number which belongs to the concept j”: it does not place us in a position to decide whether, say, the number of planets is identical with Julius Caesar. I argue that the Caesar problem which is supposed to stem originally from Frege’s tentative inductive definition of the natural numbers in The Foundations, §55 is only spurious; that the genuine Caesar problem deriving from Hume’s Principle is a purely semantic one and that the prospects of removing it by explicitly dcfining cardinal numbers as extensions of concepts (as equivalence classes of equinumerosity) or otherwise are presumably poor. Moreover, I intend to show that in The Foundations Frege could hardly have construed Hume’s Principle as a primitive truth of logic and used it as an axiom governing the cardinality operator as a primitive sign. When Frege comes to introduce his prototype of a logical object, namely courses-of-values of first-level functions — which include extensions of first-level concepts and of first-level relations as special cases — via Axiom V in Frege 1893, he encounters a variant of his old indeterminacy problem from The Foundations, now clad in formal garb. I shall confine myself to making some critical comments on Frege’s attempt to overcome the referential indeterminacy of course-of-values terms. In the third and final part, I shall try to shed new light on several aspects of Frege’s logicist programme from the point of view of both his theory of the cardinals and his theory of the reals. One issue that I focus on is Frege’s original plan, only mentioned in Frege 1884 but never carried out by him, to introduce the real numbers (tentatively) by abstraction before defining them in the end as extensions of concepts in order to resolve the intractable Caesar problem. To be sure, this problem affects Fregean abstraction principles across the board, including the one that Frege might have had in mind when he suggested to introduce the reals initially by abstraction. A second important issue, intertwined with the first, is the nature and role of identity criteria for logical objects in Frege 1884 and in Frege 1893/1903.

Seamus Bradley (LSE) gives a talk at the Rationality & Decision Meeting Munich (26-28 Jan, 2012) titled "Can free evidence be bad?" (joint work with Katie Steele).

Soroush Rafiee Rad (Tilburg) gives a talk at the Rationality & Decision Meeting Munich (26-28 Jan, 2012) titled "Updating on Conditionals" (joint work with Stephan Hartmann).

Kevin T. Kelly (CMU) gives a talk at the Rationality & Decision Meeting Munich (26-28 Jan, 2012) titled "The Bayesian Miracle".

Theo A. F. Kuipers (Groningen) gives a talk at the MCMP Colloquium (25 Jan, 2012) titled "Truth Approximation by Basic and Refined Belief Base Revision". Abstract: In a forthcoming paper, I have generalized the bridge, due to Cevolani, Crupi and Festa (2011), between the conjunctive approach of verisimilitude and AGM-Hansson belief base revision from finite propositional languages to the general case of approaching any divide of a (finite or infinite) universe, allowing all relevant interpretations. The present paper extends this general form of basic truth approximation by ‘basic’ belief base revision to refined (i.e. similarity based) truth approximation by a refined form of belief base revision, inspired by Grove’s spheres approach and Rabinowizc’s similarity foundation of it, which is similar to, but not equivalent to, so-called partial meet revision. The presentation is an improved and extended version of the paper presented at the 14th LMPS-congress (2011) in Nancy.
In a previous attempt (Kuipers, 2011) to dovetail belief revision and truth approximation, restricted to the nomic interpretation and to maximal theories, I succeeded in overcoming the problem asking for refinement by taking refined forms of belief revision into account, notably partial meet revision, using already Adam Grove’s spheres approach (Grove, 1988) and Wlodek Rabinowizc’s similarity foundation of it (Rabinowicz, 1995). However, that dovetail attempt was unsatisfactory in having an ad hoc feature already in its basic form.

Andreas Bartels (Bonn) gives a talk at the MCMP Colloquium (19 Jan, 2012) titled "Why Metrical Properties are not Powers". Abstract: What has the dispositional analysis of properties and laws (e.g. Molnar 2003, Mumford 2004, Bird 2007) to offer to the scientific understanding of physical properties? – The paper provides an answer to this question for the case of spacetime points and their metrical properties in General Relativity. The analysis shows that metrical properties are not ‘powers’, i.e. they cannot be understood as producing the effects of spacetime on matter with metaphysical necessity. Instead they possess categorical characteristics which, in connection with specific laws, explain those effects. Thus, the properties of spacetime do not favor the metaphysics of powers with respect to properties and laws.

Matthias Schirn (LMU) gives a talk at the MCMP Colloquium (18 Jan, 2012) titled "Frege’s Philosophy of Geometry". Abstract: My talk tonight is in five sections. I begin with introductory remarks. In the second section, I cast a glance at Frege’s early views on geometry and arithmetic, while in the third I comment on the relationship between Frege’s and Kant’s views of geometrical knowledge. In the fourth section, I examine, in a critical way, Frege’s remarks on space, spatial intuition, and geometrical axioms in a key passage of his book The Foundations of Arithmetic of 1884. I conclude with critical remarks on the topic “Frege and non-Euclidean geometry” and a succinct overall assessment of Frege’s philosophy of geometry.

Gerhard Schurz (Düsseldorf) gives a talk at the MCMP Colloquium (12 Jan, 2012) titled "An Empirically testable Theory of Causality". Abstract: Is the concept of causality a cognitive illusion without empirical content (as Hume taught us), or does it have a cognitively and empirically valuable function? This is the central question of this talk. I argue that should be understood as a theoretical concept, in analogy with "force" in Newtonian physics. The difference is only that 'causality' does not beong to a particular scientific discipline, but to a transdisciplinary theory. Causal-effect relations explain and/or predict certain (in)stability properties of probabilistic dependencies, namely screening-off and linking-up. I develop a theory of causality, based on causal graph theory, and prove theorems that demonstrate that this theory has empirical content, i.e., excludes logically possible probability distributions.

Matthias Unterhuber (Düsseldorf) gives a talk at the MCMP Colloquium (12 Jan, 2012) titled "Modeling AGM Belief Revision by Possible Worlds Semantics: The Case of Chellas-Segerberg Semantics". Abstract: Both AGM belief revision and conditional logics use the Ramsey test to spell out how to evaluate (indicative) conditionals. In AGM belief revision the Ramsey test is specified on the basis of belief revision operations. In my talk I will take the reverse approach and explore in how far a conditional logic interpretation of possible worlds semantics with the Ramsey test can model belief revision. For that purpose I will use the Chellas-Segerberg semantics, which does not presuppose orderings of possible worlds, but allows - as I argue in my PhD thesis - for a plausible interpretation of conditionals in terms of a qualitative Ramsey test. My approach contrasts with possible worlds accounts of AGM belief revision in the literature, which either employ a Lewis' type sphere semantics (e.g., Grove, Segerberg) or else a temporal logic semantics (e.g., Bonanno).
Matthias Unterhuber is a post-doctoral research fellow at the chair of theoretical philosophy (Gerhard Schurz) in Duesseldorf. He recently completed his PhD on possible worlds semantics for conditionals. His interests include conditional logic, modal logic, belief revision, Bayesianism, human reasoning, prototype theory and causality.

Denis Bonnay (Paris) gives a talk at the MCMP Colloquium (8 Dec, 2011) titled "Constants and Consequences (joint work with D. Westerstahl)". Abstract: Given an interpreted language and a set of logical constants, Tarski's semantic definition of logical consequence yields a consequence relation. But given a consequence relation, is there a natural way to extract from it a set of logical constants? In this talk, we will compare two ways of doing so, one purely syntactical, which is based on the idea that an expression is logical if it is essential to the validity of at least one inference, and one semantical, which is based on the idea that an expression is logical if its interpretation is fully determined by the rules for its use.

Josef Perner (Salzburg) gives a talk at the MCMP Colloquium (14 Dec, 2011) titled "Development of Counterfactual Reasoning & Emotions". Abstract: Controlling for suppositional reasoning when asked counterfactual questions children do not engage in counterfactual reasoning before 9 to 12 years. Without this control even 3 year olds can give correct answers. For instance when asked, “Suppose Carol takes her dirty shoes off before she walks across the floor, will the floor be dirty or clean?” one has no logically valid answer but one might find “clean” the more suitable option. And children tend to do so. Now when told: “Carol walked with her dirty shoes across the sparkling floor and made it all dirty,” the counterfactual question, “If Carol had taken her shoes off before walking across the floor, would the floor be dirty or clean?” can now be answered with some justification with “clean.” Children as young as 3 years do so (Harris et al 1986). However, from their responses we cannot tell whether they used counterfactual reasoning or simply applied suppositional reasoning, since both lead to the same answer. If we now change the story slightly: “Peter walked with his dirty shoes across the sparkling floor and then came Carol with her dirty shoes and walked across it. Now the floor is all dirty,” then the counterfactual question, “If Carol had taken off her shoes, …?” should be answered with “(still) dirty,” because the floor was already dirty before Carol walked across it. In contrast, suppositional reasoning would still lead to “clean,” and now only children between 9 and 12 years start giving the correct counterfactual answer. We have now established that this finding is robust for different ways of assessing counterfactual reasoning. Moreover, the onset of counterfactual emotions of regret and relief also follows the same developmental course.

Michiel van Lambalgen (Amsterdam) gives a talk at the MCMP Colloquium (10 Nov, 2011) titled "Logic or probability? An ERP study on defeasible reasoning". Abstract: Currently there is a vociferous debate over the question, whether actual human non-monotonic reasoning is best captured by a non-monotonic logic, or by probability theory. We take as concrete example the 'suppression task' in which supplementary information may lead to the withdrawal of an earlier conclusion from a modus ponens argument. We present logical and probabilistic models of this phenomenon and discuss the impact of recent EEG data on the validity of these models.

Michiel van Lambalgen (Amsterdam) and Dora Achourioti (Amsterdam) give a talk at the MCMP Colloquium (9 Nov, 2011) titled "The completeness of Kant's Table of Judgements and its consequences for philosophy of mathematics". Abstract: It is a common belief among logicians that Kant's discussion of logic in his Critique of Pure Reason has little to offer to modern practitioners, since it appears to consist only of syllogistics plus some propositional inferences. Kant himself considered logic to be an integral part of the architecture of the Critique of Pure Reason, and in the Transcendental Deductions he attempted to show that the possible logical forms of judgements lead to the 12 Categories (e.g. causality) and the principles governing their use. However, if Kant's logic is indeed 'mathematically trivial and terrifyingly narrow-minded', as one commentator put it, then Kant's own view of his procedure is untenable. The groundwork for a revisionist view of Kant's logic has been laid by Béatrice Longuenesse's book 'Kant and the capacity to judge' (1998), which argues that Kant had indeed solid grounds for linking the Categories and logical forms of judgements. Re-reading Kant with Longuenesse's thesis in mind, one sees that Kant's logic is mathematically far from trivial. We sketch some theorems which together show that Kant's logic is 'geometric logic' (Vickers, Coquand, ...). Geometric logic is expressive enough to formalise Euclidean geometry. It's natural logic is intuitionistic, and we'll discuss the implications of this result for Kant's philosophy of mathematics.

Sam Sanders (Belgium) gives a talk at the MCMP Colloquium titled "The ghosts of departed quantities as the soul of computation". Abstract: Using techniques from Nonstandard Analysis, we introduce omega-invariance: a new notion of computability based on infinitesimals. We show that omega-invariance can capture two central notions of computability, namely those provided by Recursion Theory and Constructive Analysis. We discuss the philosophical implications of these results.

Jean-Yves Beziau (Rio de Janeiro) gives a talk at the MCMP Colloquium (15 Dec, 2011) titled "The Power of the Hexagon". Abstract: In this lecture I will present and discuss the hexagon of opposition, an improvement of the square of opposition due to Robert Blanché. The hexagon of Blanché is made of a triangle of contrariety and a triangle of subcontrariety linked together by the relations of contradiction and subalternation. This hexagon includes the traditional square and can be extended to three dimensional objects giving a better understanding of modalities and negations. I will also show how this simple logical structure based on three oppositions can be applied to many different concepts ranging from logic
to music, through metalogic, economy and semiotics.

Huw Price (Cambridge) gives a talk at the MCMP Colloquium titled "Retrocausality - What Would it Take?". Abstract: Some writers argue that retrocausality offers an attractive loophole in Bell's Theorem, allowing an explanation of EPR-Bell correlations without "spooky action-at-a-distance." This idea originated more than a decade before Bell's famous result, when de Broglie's student, Olivier Costa de Beauregard, first proposed that retrocausality plays a role in EPR contexts. The proposal is difficult to assess, because there has been little work on the general question of what a world with retrocausality would "look like" - what kinds of considerations, if any, would properly lead to the conclusion that we do live in such
a world. In this talk I discuss these general issues, with the aim of bringing the more specific question as to whether quantum theory implies retrocausality into sharper focus than has hitherto been possible.

Christopher Pincock (Missouri) gives a talk at the MCMP Colloquium titled "Abstract Explanation and Difference-Making". Abstract: Recent work on scientific explanation by Woodward and Strevens has emphasized the significance of causal explanation. Both philosophers allow for a kind of non-causal explanation, but have done little to clarify its importance for science or its relationship to causal explanation. In this paper I argue for a kind of non-causal explanation that I call abstract explanation. Abstract explanation is a kind of explanation that requires a generalization of the notion of difference-making that is central to both Woodward and Strevens. From this more general perspective, one can see how non-causal relationships can make a difference to a scientific phenomenon. This sort of connection is illustrated using two cases where a mathematical truth is crucial to a scientific explanation. I conclude that only a broad notion of explanation that encompasses both causal and non-causal explanation is feasible.

Michael Esfeld (Lausanne) gives a talk at the MCMP Colloquium titled "Causal structural realism". Abstract: Der Vortrag entwickelt zwei Thesen: (1) Die fundamentalen physikalischen Eigenschaften sind in erster Linie Relationen statt intrinsischer Eigenschaften, so dass der fundamentale physikalische Bereich aus Strukturen statt einzelner Objekte mit einer intrinsischen Identität besteht. (2) Die physikalischen Strukturen sind kausal wirksam und unterscheiden sich dadurch von mathematischen Strukturen. Ich argumentiere für diese Thesen, indem ich ihre Konsequenzen sowohl für die Metaphysik von Objekten und Eigenschaften als auch für die Philosophie der Physik und die Naturphilosophie allgemein aufzeige.

Kai F. Wehmeier (Irvine) gives a talk at the MCMP Colloquium titled "The First-Order Logic of the Tractatus". Abstract: First-order logic with identity, while not isolated as a logical system in its own right until the end of the 1920s, is arguably a natural fragment of the logic envisaged by Wittgenstein in the Tractatus Logico-Philosophicus. We will discuss two distinctive features of the system sketched there, namely the abolition of the equality sign and the use of a (purportedly) single logical constant, the so-called N-operator. Building on early work by Hintikka, we identify three possible variable conventions that Wittgenstein might have used to eliminate the equality sign without loss of expressive power, and we adduce textual, historical and systematic evidence for one of these as the intended convention. With respect to the N-operator, we show that an effective notation for variable scope is implicit in the Tractatus when taken in its historical context, thus bolstering the case made by Geach against Fogelin's claim of expressive inadequacy. We close by showing how both conventions can be simultaneously implemented in perfectly workable tableau calculi.

Paul Hoyningen-Huene (Hannover) gives a talk at the MCMP Colloquium titled "Systematicity: The Nature of Science".

Johan van Benthem gives a talk at the MCMP Colloquium titled "Logic in Games". Abstract: We discuss logic *of* games as a foundation for rational interaction, suggesting a 'theory of play' extending standard game theory. We also discuss logic *as* games, the other direction of this contact. We conclude by looking at some natural entanglements between the two perspectives.

Johan van Benthem gives a talk at the MCMP Colloquium titled "Logical Dynamics of Intelligent Interaction". Abstract: We morivate the logical dynamics of information-driven agency, and then discuss it from three perspectives: as a natural extension of the traditional scope of logic, as a foundation for the interdisciplinary study of agency, and as a source of new mathematical issues of pure interest.

Andreas Stokke (Oslo) gives a talk at the MCMP Colloquium titled "Truth and Context Change". Abstract:Traditional semantics rests on the notion that the meaning of a declarative sentence is given by its truth conditions. Beginning in the 1980's this paradigm was challenged by so-called dynamic semantics. According to these theories, the meaning of a sentence is a context change potential, a measure of how an utterance of the sentence in question affects the conversational context. The shift importantly involves the claim that truth-conditional meanings can be derived from context change potentials. I argue that a standard way this has been done has problematic consequences, and I discuss the status of the dynamic turn in light of these issues.

Ingolf Max (Leipzig) gives a talk at the MCMP Colloquium titled "Applications of multi-dimensional propositional logics". Abstract: Multi-dimensional propositional logics are formal systems which we get if we extend the language of classical propositional logic by ordered n-tuples of classical formulas and suitable operators having multi-dimensional expressions as their arguments. There are several kinds of motivation to deal with multi-dimensional logics in general and with multi-dimensional propositional logics in particular. One of them is connected with the program to reconstruct systems of non-classical logics within such a syntactically extended classical framework. Another kind of motivation is the possibility to show new basic aspects of formal systems which are of some important philosophical interest. Furthermore, it is possible to use the expressive power of such systems to translate expressions of natural languages (and, e.g., structured elements of music) into more complex formal ones. The familiar one-dimensional classical language plays then the role of a theoretical language.
I will sketch the general form of multi-dimensional propositional systems with a fixed dimension n. It is possible to define several notions of validity (inconsistency) for ordered n-tuples of classical formulas using only the classical vocabulary.
With respect to a more formal application of our logics it will be shown how finite many-valued logics can be equivalently reconstructed. But it is also interesting to see under which restrictions on our languages we get these formal results. With respect to a more philosophical application it will be demonstrated that the distinctions atomic–molecular, atomic–complex depend on the underlying logic, the choice of the logical complexity of basic expressions. With respect to empirical applications and leaving the strong analogy to finite many-valued logics we can include other well-defined parts of the whole language.

Keith Stenning (Edinburgh) gives a talk at the MCMP Colloquium titled "How can we find some reasoning that people do, for which a particular logic is the appropriate model?". Abstract:The psychology of deductive reasoning has extensively investigated tasks which it has supposed classical logic to be the appropriate standard of reasoning for, and the goal that subjects adopt in its laboratories. \cite{stvl08:book} presents evidence for a range of these tasks that a substantial proportion of subjects do not adopt this goal, and that defeasible logics (specifically Logic Programming) provide better models of their understanding of what they are supposed to do.
Apart from issues about the `fit' of defeasible logics to the data of existing tasks, this argument points to the question whether untrained people do ever adopt classical logic as a model, and if so how to find tasks where this adoption is maximised and most clearly contrasted with other possible logical models.
This talk will briefly outline the narrowness of the tasks that have been used, and propose a method of designing better. Results from a pilot experiment will illustrate some initial progress, and perhaps throw some light on general issues about how to match empirical evidence to logical model.

Rasmus K. Rendsvig (Roskilde) gives a talk at the MCMP Colloquium titled "Modeling Semantic Competence: a Critical Review of Frege's Puzzle (as an argument against Millianism)". Abstract: I will discuss Frege's Puzzle about Identity as an argument against a Millian theory of meaning for proper names. The key notion analyzed is semantic competence. Strict notions of semantic competence are extrapolated from a two-sorted first order epistemic logical modeling of a cognitive neuropsychological theory of the structure of lexical competence. The model allows for a rigorous analysis of Frege's argument. The theory and model of lexical semantic competence includes a multitude of types of competence, each yielding a different argument, far from all being as decisive against Millianism as has been the mainstream assumption in 20th century philosophy of language.

Markus Pantsar (Helsinki) gives a talk at the MCMP Colloquium titled "Empirical Research and The Philosophy of Mathematics". Abstract:In the philosophy of mathematics, one of the most fundamental questions concerns how mathematical methods help us get knowledge of the world. In this, mathematics with its apparent a priori character seems to be radically different from the empirical methods we otherwise rely on in science. This relation between the mathematical and the empirical has received extensive treatment from the likes of Quine, Putnam and Kitcher. In this talk, however, I want to focus on a different approach: what can we learn empirically about mathematical thinking and, in particular, what relevance does this have in philosophy?

For this purpose, I will present some examples of results from psychology, animalstudies, sociology and the study of mathematical practice, and evaluate their philosophical importance. While such results are often inconclusive or irrelevant, I will contend that there are numerous studies concerning primitive mathematical thinking that we should take seriously in philosophy. In addition, I will formulate the outlines of an epistemological theory that can retain the special character of mathematical knowledge while not making it empirically unfeasible.

Gerhard Ernst (Stuttgart) gives a talk at the MCMP Colloquium titled "Two Varieties of Knowledge". Abstract:
The analysis of knowledge is, as it seems, a doomed project. Many definitions have been proposed – only to be refuted immediately. In this paper I argue that the reason for this predicament is that there are two slightly different varieties of knowledge which have to be analysed separately. So, the reason why no definition of knowledge is satisfactory is that there is no such defintion – but maybe there are two!

Patrick Suppes (Stanford) gives a talk at the MCMP Colloquium titled "Neglect of Independence and Uncertainty (or Randomness) in the Axioms of Probability".

Timothy Williamson (Oxford) gives a talk at the MCMP Colloquium titled "On a Proposed Extension of Infinitary Logic". Abstract: In discussing ‘translation’ schemes between possibilist discourse about merely possible objects and actualist discourse that abjures such objects, Kit Fine proposed interpreting quantifiers over pluralities or sets of possibilia using infinite sequences of modal operators and actualist quantifiers. After explaining the philosophical background, the talk will concern the more technical problem of interpreting such infinite sequences of operators. Various proposals will be assessed. The only ones that work depend on postulating possibilia in the meta-language.

Simone Duca (RUB & HHU) gives a talk at the MCMP Colloquium titled "A Regret-Based Model for Wishful Thinkers". Abstract: The study of decision making can be divided into three categories, according to how much information is available to the agent. We talk of decision making under risk, uncertainty and ignorance, whenever the agent is facing a decision under complete probabilistic knowledge, incomplete probabilistic knowledge and no probabilistic knowledge re- spectively. In my talk, I wish to focus on decision making under ig- norance and propose a decision model where the agent either has no prior probabilities at all or she deliberately ignores them when given. The model is an attempt to capture two facts: a) people are not very good at reasoning with probabilities and b) people tend to be unreal- istically optimistic when making a decision. In other words, in many situations, people are inveterate wishful thinkers. This can be repre- sented by applying a non-probabilistic rule which aims at minimising the worst-case scenario regret. I discuss some properties and applica- tions of the model and give evidence for the descriptive aptness of the model.

Timothy Williamson (Oxford) gives a talk at the MCMP Colloquium titled "Logics as Scientific Theories". Abstract: Logic has far more in common with other branches of science than is usually recognized. One major aim of science is to develop theories that are true, highly general, and maximally informative subject to those constraints. When the generality requirement is made precise in some natural ways, related to Tarski’s account of logical consequence, the resultant theories meet central requirements for logical systems. An appropriate methodology for choosing between different candidate theories has many similarities to the methodology for theory choice in other branches of science. This involves no reduction of logic to psychology, linguistics, or specifically natural science. The talk will be illustrated with examples from modal logic.

Mark Colyvan (Sydney) gives a talk at the MCMP Colloquium titled "A Generalised Sorites ". Abstract: I present a topological version of the sorites paradox that holds both practical and theoretical interest. On the theoretical side, the topological sorites reveals shortcomings of some of the standard philosophical treatments of the garden-variety sorites, it forces us to rethink our definition of 'vagueness', and it suggests that the liar and sorites paradoxes are much closer related than one might think. On the practical side, the topological sorites is found in various applied scientific contexts, giving rise to a particularly nasty kind of uncertainty; its interest is not merely philosophical.

Daniel Cohnitz (Tartu) gives a talk at the MCMP Colloquium titled "Are Theories of Reference Empirically Testable?".

Mark Colyvan (Sydney) gives a talk at the MCMP Colloquium titled "The Ins and Outs of Mathematical Explanation". Abstract: Proofs of mathematical theorems tell us that the theorem is true, but some proofs go further and tell us why the theorem is true. That is, some, but not all, proofs are explanatory. Call this intra-mathematical explanation. It has been argued that whenever there are physical applications of the theorems in question, we also have mathematical explanations of physical phenomena. Call this extra-mathematical explanation. In this paper I will consider both intra- and extra-mathematical explanations and discuss why they are of philosophical interest. I will also make some speculative remarks about two promising accounts for a theory of mathematical explanation.

Paul Harrenstein (TUM) gives a talk at the Bristol-Munich Workshop titled "Set-Rationalizable Choice and Self-Stability".

Martin Rechenauer (LMU) gives a talk at the Bristol-Munich Workshop titled "Variations of Avoiding the Arrow Impasse".

Hannes Leitgeb (MCMP/LMU) gives a talk at the Bristol-Munich Workshop titled "A Dictator Theorem on Belief Revision Derived from Arrow's Theorem".

Kit Patrick (Bristol) and Kate Hodesdon (Bristol) give a talk at the Bristol-Munich Workshop titled "Is theory choice using epistemic virtues possible?".

Hans-Christoph Kotzsch (MCMP/LMU) gives a talk at the Bristol-Munich Workshop titled "Modal Logic From a Categorical Point of View".

Vincenzo Crupi (MCMP/LMU) gives a talk at the Bristol-Munich Workshop titled "Explorations in Bayesian confirmation and models of information search".

Neil Coleman (Bristol) gives a talk at the Bristol-Munich Workshop titled "Logic as Modelling".

Thomas Meier (MCMP/LMU) gives a talk at the Bristol-Munich Workshop titled "Structural Realism in Linguistics".

Benjamin Eva (Bristol) gives a talk at the Bristol-Munich Workshop titled "Meaning and Interpretation in Birkhoff/Von Neumann quantum logic".

Florian Steinberger (MCMP/LMU) gives a talk at the Bristol-Munich Workshop titled "Is logical knowledge dispositional?".

Marianna Antonutti M. (Bristol) gives a talk at the Bristol-Munich Workshop titled "Inexhaustibility and Reflection".

Julien Murzi (MCMP/LMU) gives a talk at the Bristol-Munich Workshop titled "Validity Curry".

Johannes Korbmacher (MCMP/LMU) gives a talk at the Bristol-Munich Workshop titled "An Ontological Argument for the Existence of Numbers?".

Stephan Hartmann (Tilburg) gives a talk at the Workshop on Mathematical Philosophy titled "Voting, Deliberation and Truth". Abstract: There are various ways to reach a group decision. One way is to simply vote and decide what the majority votes for. This procedure receives some epistemological support from the Condorcet Jury Theorem. Alternatively, the group members may prefer to deliberate and will eventually reach a decision that everybody endorses -- a consensus. While the latter procedure has the advantage that it makes everybody happy (as everybody endorses the consensus), it has the disadvantage that it is difficult to implement, especially for larger groups. What is more, a deliberation is easy to bias as those group members who make others change their mind may not necessarily be the best truth-trackers. But even if no such biases are present, the consensus may be far away from the truth. And so we ask: When is deliberation a better method to track the truth than simple majority voting? To address this question, we propose a Bayesian model of rational non-strategic deliberation and compare it to the straight forward voting procedure. The talk is based on joint work with Soroush Rafiee Rad.

Vincent Hendricks (Copenhagen/Columbia) gives a talk at the Workshop on Mathematical Philosophy titled "IPAD – Information Processing and the Analysis of Democracy". Abstract: Only one species have configured a democracy and decided to live according to deliberative democratic guidelines. The configuration and decision is particular to man. A deliberative democracy is characterized by both group deliberation, decision and action. Central to this epistemic composite is information as information processing is an essential fabric of rational deliberation, decision and action which in turn amount to the rational interaction among members of a group or a democracy. Thus, a robust deliberative democracy is the quintessential example of rational agent interaction. This intimate connection fuels a new research paradigm in interdisciplinary philosophy: IPAD -- Information Processing and the Analysis of Democracy.

Members of the MCMP (Julien Murzi, Johannes Stern, Martin Fischer, Ole Hjortland, Marta Sznayder, Norbert Gratzl, Johannes Korbmacher) present their current research

Volker Halbach (Oxford) gives a talk at the Workshop on Mathematical Philosophy titled "Self-reference". Abstract: What does it mean for a sentence to say about itself that it is P? Here P can stand for any unary sentential function such as 'is provable', 'is not provable', 'is true', or 'is a sentence'. I will study this question in a metamathematical setting. After reviewing some early attempts to tackle the question and their impact on problems in metamathematics such as Henkin's problem, I will put forward a new proposal and test its adequacy with some examples.

Branden Fitelson (Rutgers) gives a talk at the Workshop on Mathematical Philosophy titled "An "Evidentialist" Worry About Joyce's Argument for Probabilism.". Abstract: In this talk, I will raise a potential problem for Joyce's argument for probabilism (and sufficiently similar "accuracy-dominance"-based arguments for probabilism). The problem involves a potential conflict between "accuracy-dominance" (coherence) norms and certain "evidential" norms for credences. An interesting analogy with the case of full belief is also drawn (which connects up with a larger project on the relationship between accuracy, coherence, and evidential norms for various sorts of judgments). This is joint work with Kenny Easwaran.

Members of the MCMP (Roland Poellinger, Florian Steinberger, Thomas Meier, Vincenzo Crupi and Olivier Roy) present their current research.

David Ripley (University of Melbourne) gives a talk at the MCMP Colloquium titled "Tonk, Nontransitivity, and Tolerance".

Teddy Seidenfeld (CMU) gives a talk in the talk series "MCMP & Statistics Department" titled "Three contrasts between two senses of coherence" (Joint work with M. J. Schervish and J. B. Kadane – Statistics, CMU). Abstract: B. de Finetti defended two senses of coherence in providing foundations for his theory of subjective probabilities. Coherence 1 requires that when a decision maker announces fair prices for random variables these are immune to a uniform sure-loss - no Book is possible using finitely many fair contracts! Coherence 2 requires that when a decision maker's forecasts for a finite set of random variables are evaluated by Brier Score - squared error loss - there is no rival set of forecasts that dominate with a uniformly better score for sure. De Finetti established these two concepts are equivalent: fair prices are coherent 1 if and only if they constitute a coherent 2 set of forecasts if and only if they are the expected values for the variables under some common (finitely additive) personal probability.

I report three additional contrasts between these two senses of coherence. One contrast (relating to finitely additive probabilities) favors coherence 2. One contrast (relating to decisions with moral hazard) favors coherence 1. The third contrast relates to the challenge of state-dependent utilities.

Paul Dicken (Cambridge) gives a talk at the MCMP Workshop on Carnap titled "Tolerance & Voluntarism". Abstract: Carnap's dissolution of the scientific realism debate rests upon two central claims:the first regarding the appropriate logical reconstruction of a scientific theory;the second, a background conception of the nature of ontological dispute. Recentwork has focused on the first of these claims; in this talk I discuss the second,and relate it to similar moves made by van Fraassen in his own articulation of empiricism.

Michael Friedman (Stanford) gives a talk at the MCMP Workshop on Carnap titled "Carnap's Logico-Mathematical Neutrality between Realism and Instrumentalism". Abstract: I discuss the evolution of Carnap’s treatment of theoretical terms from the late1930s to his mature work on the Ramsey sentence formulation of scientific theoriesin the late 1950s and 1960s.I concentrate on Carnap’s use of this device toremain completely neutral between realism and instrumentalism.A central point ofdiscussion is his commitment to a purely logico-mathematical interpretation of thequantified existential variables in the Ramsey sentence.Far from being adesperate or ad hoc maneuver, I argue that this is essential to Carnap’s point ofview and, in particular, to the way in which he understands the characteristicallyabstract representations of modern mathematical physics throughout his intellectualcareer.In the end, Carnap recommends nothing more nor less than that we eschewfruitless “ontological” disputes in favor of cooperating with contemporarymathematical physicists in attempting (axiomatically) to clarify the mathematicaland conceptual foundations of their discipline.)

André Carus (Chicago/Cambridge) gives a talk at the MCMP Workshop on Carnap titled "From Analysis to Explication". Abstract: Analytic philosophy was named for the "analysis" of propositions begun by Russelland Moore in the first years of the twentieth century, epitomized by the theory ofdescriptions.This style of analysis has been joined by many others since then. But they all share certain common defects, which are overcome by "explication," areplacement for all forms of analysis developed by Carnap in his later years.However, it was suggested by Quine, Dreben, and their students that Carnap's form ofexplication depends on metaphysical assumptions Quine dispensed with.It is arguedin this paper that this suggestion is based on misunderstandings, and thatexplication is preferable to analysis, especially since it offers a more plausible picture of philosophy.

Georg Schiemer (MCMP/LMU) gives a talk at the MCMP Workshop on Carnap titled "Carnap on extremal axioms and categoricity". Abstract: The talk will investigate Carnap's early contributions to formal semantics in his work on general axiomatics between 1928 and 1936. Inparticular, we give a historically sensitive discussion of Carnap's theoryof extremal axioms from the late 1920s onwards. The main focus is seton the unpublished documents of the projected second part of UntersuchungenzurallgemeinenAxiomatik (RC 081-01-01 to 081-01-33).We present a formal reconstruction of the semantic notions 'formalmodel', 'model structure', und 'submodel' first formulated there. Themain interprctive issue addressed in the talk concerns Carnap's understandingof the relationship between the "completenessof the models"of an axiomatic theory and other metatheoretic notions investigatedby him at the time, most notably that of semantic completeness andcategoricity.

Steve Awodey (CMU/MCMP) gives a talk at the MCMP Workshop on Carnap titled "On an occasionally heard objection to Carnap's conception of logical truth".

Michael Friedman (Stanford) gives a talk at the MCMP Colloquium titled "Mathematical Science, Naturalism, and Normativity". Abstract: I address concerns in contemporary philosophy about the place of mathematics andmoral (and other) norms in a naturalistic world picture. I think that these worriesare largely misplaced, and I address them with an historical narrative from Platoto Kant, beginning from the fact that Plato's original "platonism" (in the theoryof forms) tried to give a kind of unified account of both mathematics and moralnorms. I contend that this was not mysterious or "spooky" but a perfectlyreasonable and intelligible response to the state of mathematical science of thetime—especially concerned with the relationship between ideal mathematicalstructures and the physical world. I then explore how this last relationship wasfundamentally transformed in the early modern period, beginning with Galileo, andcontinuing from Descartes, through Leibniz and Newton, and finally to Kant—where aradically new kind of relationship between mathematics (especially appliedmathematics) and moral normativity (still in the spirit of Plato) then emerged.

Graciela di Pierris (Stanford) gives a talk at the MCMP Colloquium titled "Hume on Space and Geometry". Abstract: Hume’s discussion of space, time, and mathematics in Part II of Book I of theTreatise has appeared to many commentators as one of the weakest parts of his work.I argue, on the contrary, that Hume’s views on space and geometry are deeplyconnected with his radically empiricist reliance on phenomenologically given sensoryimages. He insightfully shows that, working within this epistemological model, wecannot attain complete certainty about the continuum but only at most about discretequantity. Therefore, geometry, in contrast to arithmetic, cannot be a fully exactscience. Nevertheless, Hume does have an illuminating account of Euclid’s geometryas an axiomatic demonstrative science, ultimately based on the phenomenologicalapprehension of the “easiest and least deceitful” sensory images of geometricalfigures. Hume’s discussion, in my view, demonstrates the severe limitations of apurely empiricist interpretation of the role of such figures (diagrams) in geometry.

Jan-Willem Romeijn (University of Groningen) gives a talk in the talk series "MCMP & Statistics Department" titled "Frequencies, Chances and Undefinable Sets". Abstract: In this talk I aim to clarify the concept of chance. The talk consists of two parts, concerning the epistemology and metaphysics of chance respectively. In the first part I consider statistical hypothese and their role in inference. I maintain that statistical hypotheses are best explicated along frequentist lines, following the theory of von Mises. I will argue that the well-known problems for frequentism do not apply in the inferential context. In the second part of the talk I ask what relation obtains between these frequentist hypotheses an the world. I will show that we can avoid the problem of the reference class, as well as the closely related conflict between determinism and chance, by means of a formal antireductionist argument: events can be assigned meaningful and nontrivial chances if they correspond to undefinable sets of events in the reducing theory.

Neil Tennant (Ohio State University) gives a talk at the MCMP Colloquium titled "Core Logic".

Matthew Braham (University of Bayreuth) gives a talk at the MCMP Colloquium titled "The Contradiction in Will Test: A Reconstruction".

Hannes Leitgeb (MCMP/LMU) gives a lecture at the Carl-Friedrich-von-Siemens-Stiftung titled "Logic and the Brain". Introductory words by Enno Aufderheide (secretary gemeral, Humboldt Foundation).

Tomasz Placek (Jagiellonian University, Kraków) gives a talk at the MCMP Colloquium titled "Possibilities without possible worlds/histories". Abstract: Possible worlds have turned out to be a particularly useful tool of modal metaphysics, although their globality makes them philosophically suspect. Hence, it would be desirable to arrive at some local modal notions that could be used instead of possible worlds. In this talk I will focus on what is known as historical (or real) modalities, an example of which is tomorrow's sea-battle. The modalities involved in this example are local since they refer to relatively small chunks of our world: a gathering of inimical fleets on a bay near-by has two alternative possible future continuations: one with a sea-battle and the other with no-sea battle. The objective of this talk is to sketch a theory of such modalities that is framed in terms of possible continuations rather than possible worlds or possible histories. The proposal will be tested as a semantic theory for a language with historical modalities, tenses, and indexicals.

Alistair M. C. Isaac (University of Michigan) gives a talk at the MCMP Colloquium titled "Diachronic Dutch Book Arguments for Forgetful Agents". Abstract: I present a general strategy for applying diachronic Dutch book arguments to bounded agents, with particular focus on forgetful agents. Dutch book arguments were introduced by subjectivists about probability to test the consistency of synchronic epistemic norms. Diachronic Dutch book arguments (DDBs) apply this technique to test the consistency of diachronic epistemic norms, norms about how beliefs change in time. Examples like forgetfulness have led some to doubt the relevance of DDBs for evaluating diachronic norms. I argue that there is no problem in applying DDBs to formally specified decision problems involving forgetfulness. The real worry here is whether these formal problems capture the relevant details of real world decision-making situations. I suggest some general criteria for making this assessment and defend the formalization of decision problems involving bounded agents, and their investigation via DDBs, as essential tools for evaluating epistemic norms.

Richard Bradley (LSE) gives a talk at the MCMP Colloquium titled "Conditionals and Suppositions". Abstract:

Adams' Thesis - the claim that the probabilities of indicative conditionals equal the conditional probabilities of their consequents given their antecedents - has proven impossible to accommodate within orthodox possible worlds semantics. This paper considers the approaches to the problem taken by Jeffrey and Stalnaker (1994) and by McGee (1989), but rejects them on the grounds that they imply a false principle, namely that probability of a conditional is independent of any proposition inconsistent with its antecedent. Instead it is proposed that the semantic contents of conditionals be treated as sets of vectors of worlds, not worlds, where each co-ordinate of a vector specifies the world that is or would be true under some supposition. It is shown that this treatment implies the truth of Adams' Thesis whenever the mode of supposition is evidential.

Peter Schroeder-Heister (Tübingen) gives a talk at the MCMP Colloquium Mathematical Philosophy - first part: "Proof-theoretic semantics and the format of deductive reasoning", second part: "Prawitz's completeness conjecture (A sketch of some ideas)".

Charles B. Cross (University of Georgia) gives a talk at the MCMP Workshop on Bayesian Methods in Philosophy titled "Knowledge about Probability in the Monty Hall Problem".

Hannes Leitgeb (MCMP/LMU) gives a talk at the MCMP Workshop on Bayesian Methods in Philosophy titled "The Lockean Thesis Revisited".

Niki Pfeifer (MCMP/LMU) gives a talk at the MCMP Workshop on Bayesian Methods in Philosophy titled "Applying coherence based probability logic to philosophical problems".

Vincenzo Crupi (MCMP/LMU) gives a talk at the MCMP Workshop on Bayesian Methods in Philosophy titled "Formal epistemological explication (news for the Bayesian agenda)".

Branden Fitelson (Rutgers University) gives a talk at the MCMP Workshop on Bayesian Methods in Philosophy titled "Accuracy & Coherence". Abstract: In this talk, I will explore a new way of thinking about the relationship between accuracy norms and coherence norms in epistemology (generally). In the first part of the talk, I will apply the basic ideas to qualitative judgments (belief and disbelief). This will lead to an interesting coherence norm for qualitative judgments (but one which is weaker than classical deductive consistency). In the second part of the talk, I will explain how the approach can be applied to comparative confidence judgments. Again, this will lead to coherence norms that are weaker than classical (comparative probabilistic) coherence norms. Along the way, I will explain how evidential norms can come into conflict with even the weaker coherence norms suggested by our approach.

Branden Fitelson (Rutgers University) gives a talk at the MCMP Workshop on Computational Metaphysics titled "Russellian Descriptions & Gibbardian Indicatives (Two Case Studies Involving Automated Reasoning)". Abstract: The first part of this talk (which is joint work with Paul Oppenheimer) will be about the perils of representing claims involving Russellian definite descriptions in an "automated reasoning friendly" way. I will explain how to eliminate Russellian descriptions, so as to yield logically equivalent (and automated reasoning friendly) statements. This is a special case of a more general problem -- which is representing philosophical theories/explications in a way that automated reasoning tools can understand. The second part of the talk shows how automated reasoning tools can be useful in clarifying the structure (and requisite presuppositions) of well-known philosophical "theorems". Here, the example comes from the philosophy of language, and it involves a certain "triviality result" or "collapse theorem" for the indicative conditional that was first discussed by Gibbard. I show how one can use automated reasoning tools to provide a precise, formal rendition of Gibbard's "theorem". This turns out to be rather revealing about what is (and is not) essential to Gibbard's argument.

Ed Zalta (CSLI Stanford) gives a talk at the MCMP Workshop on Computational Metaphysics titled "Toward Leibniz's Goal of a Computational Metaphysics".

Roland Poellinger (MCMP/LMU Munich) gives a talk at the MCMP Workshop on Computational Metaphysics titled "Computing Non-Causal Knowledge for Causal Reasoning". Abstract: We use logical and mathematical knowledge to generate causal claims. Inter-definitions or semantic overlap cannot be consistently embedded in standard Bayes net causal models since in many cases the Markov requirement will be violated. These considerations motivate an extension of Bayes net causal models to also allow for the embedding of Epistemic Contours (ECs). Such non-causal functions are consistently computable in Causal Knowledge Patterns (CKPs). An application of the framework can be found, e.g., in the recording of the talk "The Mind-Brain Entanglement".

Stephan Hartmann (Tilburg) gives a talk at the MCMP Workshop on Computational Metaphysics titled "On the Emergence of Descriptive Norms".

Catarina Duthil-Novaes (ILLC/Amsterdam) gives at talk at the MCMP Colloquium titled "Cognitive motivations for treating formalisms as calculi". Abstract: In The Logical Syntax of Language, Carnap famously recommended that logical languages be treated as mere calculi, and that their symbols be viewed as meaningless; reasoning with the system is to be guided solely on the basis of its rules of transformation. Carnap˙s main motivation for this recommendation seems to be related to a concern with precision and exactness.

In my talk, I argue that Carnap was right in insisting on the benefits of treating logical formalisms as calculi, but he was wrong in thinking that enhanced precision is the main advantage of this approach. Instead, I argue that a deeper impact of treating formalisms as calculi is of a cognitive nature: by adopting this stance, the reasoner is able to counter some of her „default“ reasoning tendencies, which (although advantageous in most practical situations) may hinder the discovery of novel facts in scientific contexts. One of these cognitive tendencies is the constant search for confirmation for the beliefs one already holds, as extensively documented and studied in the psychology of reasoning literature, and often referred to as confirmation bias/belief bias.

Treating formalisms as meaningless and relying on their well-defined rules of formation and transformation allows the reasoner to counter her own belief bias for two main reasons: it 'switches off' semantic activation, which is thought to be a largely automatic cognitive process, and it externalizes reasoning processes; they now take place largely through the manipulation of the notation. I argue moreover that the manipulation of the notation engages predominantly sensorimotor processes rather than being carried out internally: the agent is literally 'thinking on the paper'.

The analysis relies heavily on empirical data from psychology and cognitive sciences, and is largely inspired by recent literature on extended cognition (in particular Clark, Menary and Sutton). If I am right, formal languages treated as calculi and viewed as external cognitive artifacts offer a crucial cognitive boost to human agents, in particular in that they seem to produce a beneficial de-biasing effect.

Charles B. Cross (University of Georgia) gives a talk at the MCMP Colloquium titled "Conclusive Reasons, Transmission, and Epistemic Closure".

Catarina Duthil-Novaes (ILLC/Amsterdam) gives a talk at the MCMP Colloquium titled "The 'fitting problem' for logical semantic systems". Abstract: When applying logical tools to study a given extra-theoretical, informal phenomenon, it is now customary to design a deductive system, and a semantic system based on a class of mathematical structures. The assumption seems to be that they would each capture specific aspects of the target phenomenon. Kreisel has famously offered an argument on how, if there is a proof of completeness for the deductive system with respect to the semantic system, the target phenomenon becomes „squeezed“ between the extension of the two, thus ensuring the extensional adequacy of the technical apparatuses with respect to the target phenomenon: the so-called squeezing argument. However, besides a proof of completeness, for the squeezing argument to go through, two premises must obtain (for a fact e occurring within the range of the target phenomenon):

(1) If e is the case according to the deductive system, then e is the case according to the target phenomenon.
(2) If e is the case according to the target phenomenon, then e is the case according to the semantic system.

In other words, the semantic system would provide the necessary conditions for e to be the case according to the target phenomenon, while the deductive system would provide the relevant sufficient conditions. But clearly, both (1) and (2) rely crucially on the intuitive adequacy of the deductive and the semantic systems for the target phenomenon.

In my talk, I focus on the (in)plausibility of instances of (2), and argue That the adequacy of a semantic system for a given target phenomenon must not be taken for granted. In particular, I discuss the results presented in (Andrade-Lotero & Dutilh Novaes forthcoming) on multiple semantic systems for Aristotelian syllogistic, which are all sound and complete with respect to a reasonable deductive system for syllogistic (Corcoran˙s system D), but which are not extensionally equivalent; indeed, as soon as the language is enriched, they start disagreeing with each other as to which syllogistic arguments (in the enriched language) are valid. A plurality of apparently adequate semantic systems for a given target phenomenon brings to the fore what I describe as the „fitting problem“ for logical semantic systems: what is to guarantee that these technical apparatuses adequately capture significant aspects of the target phenomenon? If the different candidates have strikingly different properties (as is the case here), then they cannot all be adequate semantic systems for the target phenomenon. More generally, the analysis illustrates the need for criteria of adequacy for semantic systems based on mathematical structures. Moreover, taking Aristotelian syllogistic as a case study illustrates the fruitfulness but also the complexity of employing logical tools in historical analyses.

Steve Awodey (CMU/MCMP) gives a talk at the MCMP Workshop on Modality titled "Modality and Categories".

Martin Fischer (MCMP/LMU Munich) gives a talk at the MCMP Workshop on Modality titled "Interacting Modal Predicates".

Charles B. Cross (University of Georgia) gives a talk at the MCMP Workshop on Modality titled "Every Proposition is a Counterfactual (the Robustly Contingent Ones Nontrivially So)".

Ed Zalta (Stanford) gives a talk at the MCMP Workshop on Modality titled "Possible Worlds, The Lewis Principle, and the Myth of a Large Ontology".

Richard Pettigrew (University of Bristol) gives a talk at the MCMP Colloquium titled "Accuracy, Chance, and the Principal Principle"

Alexandru Baltag (ILLC Amsterdam) gives a talk at the MCMP Colloquium titled "Tracking the Truth Requires a Non-wellfounded Prior! A Study in the Learning Power (and Limits) of Bayesian (and Qualitative) Update". Abstract: The talk is about tracking "full truth" in the limit by iterated belief updates. Unlike Sonja's talk (which focused on finite models), we now allow the initial model (and thus the initial set of epistemic possibilities) to be infinite. We compare the truth-tracking power of various belief-revision methods, including probabilistic conditioning (also known as Bayesian update) and some of its qualitative, "plausibilistic" analogues (conditioning, lexicographic revision, minimal revision). We focus in particular on the question on whether any of these methods is "universal" (i.e. as good at tracking the truth as any other learning method). We show that this is not the case, as long as we keep the standard probabilistic (or belief-revision) setting. On the positive side, we show that if we consider appropriate generalizations of conditioning in a non-standard, non-wellfounded setting, then universality is achieved for some (though not all) of these learning methods. In the qualitative case, this means that we need to allow the prior plausibility relation to be a non-wellfounded (though total) preorder. In the probabilistic case, this means moving to a generalized conditional probability setting, in which the family of "cores" (or "strong beliefs") may be non-wellfounded (when ordered by inclusion or logical entailament). As a consequence, neither the family of classical probability spaces, nor lexicographic probability spaces, and not even the family of all countably additive (conditional) probability spaces, are rich enough to make Bayesian conditioning "universal", from a Learning Theoretic point of view! This talk is based on joint work with Nina Gierasimczuk and Sonja Smets.

Berit Brogaard (University of Missouri, St. Louis) gives a talk at the MCMP Colloquium titled "Do 'Looks' Reports Reflect the Contents of Perception?"

Volker Halbach (Oxford) gives a talk at the MCMP Colloquium titled "The conservativity of truth and the disentanglement of syntax and semantics"

Douglas Patterson (Universität Leipzig) gives a talk at the MCMP Colloquium titled "Theory and Concept in Tarski's Philosophy of Language". Abstract: In this talk I will set out some of the background of Tarski's famous work on truth and semantics by looking at important views of his teachers Tadeusz Kotarbinski and Stanislaw Lesniewski in the philosophy of langauge and the "methodology of deductive sciences". With the understanding of the assumed philosophy of language and logic of the important articles set out in this manner, I will look at a number of issues familiar from the literature. I will sort out Tarski's conception of "material adequacy", discuss the relationship between a Tarskian definition of truth and a conceptual analysis of a more familiar sort, and consider the consequences of the views presented for the question of whether Tarski was a deflationist or a correspondence theorist.

Sonja Smets (University of Groningen) gives a talk at the MCMP Colloquium titled "Belief Dynamics under Iterated Revision: Cycles, Fixed Points and Truth-tracking". Abstract: We investigate the long-term behavior of processes of learning by iterated belief-revision with new truthful information. In the case of higher-order doxastic sentences, the iterated revision can even be induced by repeated learning of the same sentence (which conveys new truths at each stage by referring to the agent's own current beliefs at that stage). For a number of belief-revision methods (conditioning, lexicographic revision and minimal revision), we investigate the conditions in which iterated belief revision with truthful information stabilizes: while the process of model-changing by iterated conditioning always leads eventually to a fixed point (and hence all doxastic attitudes, including conditional beliefs, strong beliefs, and any form of "knowledge", eventually stabilize), this is not the case for other belief-revision methods. We show that infinite revision cycles exist (even when the initial model is finite and even when in the case of repeated revision with one single true sentence), but we also give syntactic and semantic conditions ensuring that beliefs stabilize in the limit. Finally, we look at the issue of convergence to truth, giving both sufficient conditions ensuring that revision stabilizes on true beliefs, and (stronger) conditions ensuring that the process stabilizes on "full truth" (i.e. beliefs that are both true and complete). This talk is based on joint work with A. Baltag.

Once again, a candidate nominated by Ludwig-Maximilians-Universität (LMU) München has been awarded one of the coveted Alexander von Humboldt Professorships. The philosopher and mathematician Hannes Leitgeb, Professor of Mathematical Logic and Philosophy of Mathematics at the University of Bristol (UK), was selected to receive the accolade by an expert committee set up by the Humboldt Foundation. The prize, which is worth 5 million Euros, is financed by the Federal Ministry for Education and Research, and is the most richly endowed award of its kind in Germany. Leitgeb is one of the leading proponents of an approach to problems in logic, philosophy and the foundations of the scientific method that exploits insights from both philosophical analyses and mathematical theories of provability. In effect, he formulates philosophical questions as precisely posed mathematical propositions, allowing him not only to come up with solutions, but also to explain them with the utmost clarity. Hannes Leitgeb becomes the LMU’s third Humboldt Professor, joining Ulrike Gaul (Systems Biology) and Georgi Dvali (Astrophysics).

Leitgeb is one of the most prominent scholars worldwide who tackle analytical philosophy and cognitive sciences with the help of mathematical logic. This multi-pronged approach is motivated by the conviction that philosophical investigations can best be advanced if their fundamental assumptions can be recast as mathematical models that make them more transparent and simpler to describe. As a Humboldt Professor at LMU, Leitgeb will provide the basis for the planned Munich Center for Mathematical Philosophy, Language and Cognition, in which postgraduate and postdoctoral students in the fields of Philosophy, Logic and Mathematics will work together on common problems.

The new Center will also collaborate with the Munich Center for Neuroscience, Brain and Mind (MCN). This institution was established in 2007, as the result of an internal competition (LMUinnovativ) to identify innovative ways of tackling questions related to the mind-brain problem. Its members utilize the whole spectrum of disciplines relevant to the neurosciences, from molecular biology, through systemic neurobiology, psychology and neurology, to philosophy. By fostering cooperation between widely diverse areas of study, the two Centers hope to make internationally significant contributions to theoretical and empirical brain sciences. Hannes Leitgeb's interdisciplinary orientation will help further sharpen the profile of the LMU’s Faculty of Philosophy by renewing its long-standing focus on the intersection between philososphy, logic and foundations of science, which is closely associated with the work of Wolfgang Stegmuller. This focus will also be given a future-oriented and internationally apparent impetus.

Leitgeb first forged a firm link between philosophical logic and the cognitive sciences in his book “Inference on the Low Level. An Investigation into Deduction, Nonmonotonic Reasoning, and the Philosophy of Cognition”. Here he showed that, under certain circumstances, state transitions in neural networks can be understood as simple ‘if ... then’ inferences. These in turn are known to follow laws governing the behaviour of logical systems that have emerged from studies in the philosophy of language and in theoretical computer science. Leitgeb is currently working on a monograph devoted to Rudolf Carnap’s “The Logical Structure of the World”. He hopes to give this classic text a new lease of life by highlighting the relevance of Carnap’s insights for modern scientific research. One of the aims of this latest endeavour is to discover how to transform theoretical scientific models into propositions framed in terms of our immediate sensory perceptions. To this end, Leitgeb is developing a theory of probability that permits valid inferences about systems which are themselves capable of generating statements about their own probability.

Hannes Leitgeb was born in Salzburg in 1972, and studied Mathematics, Philosophy and Computer Science at Salzburg University, earning doctoral degrees in both Mathematics and Philosophy. In 2002 he became a staff member in the Department of Philosophy at his alma mater. Two years later he was awarded an Erwin Schrödinger Fellowship by the Austrian Science Foundation (FWF), and spent the following year at Stanford University in California. He moved to the University of Bristol (UK) in 2005, and was named Professor of Mathematical Logic and Philosophy of Mathematics in 2007. In the same year, he won the Philip Leverhulme Prize awarded by the Leverhulme Trust, and in 2009 the Humboldt Foundation conferred its Friedrich Wilhelm Bessel Prize for Research upon him. The latter honour enabled him to spend 6 months as a Research Professor at Heinrich Heine University in Düsseldorf.

(LMU press release, Munich, 24 February 2010)