November 03, 2004, 6-7:30 PM in 234 Moses Hall

Richard Zach (University of Calgary, Philosophy)

Vagueness and infinitely many truth values

A number attempts to give accounts of vagueness in formal terms have involved many-valued logics. One particularly appealing–at first blush–proposal of this sort had it that truth comes in infinitely many “degrees,” and that the logic of vagueness is continuum-valued Lukasiewicz logic. This and other truth-functional approaches have met with a sizable number of objections, and Williamson and others have concluded that these attempts have ended in failure. I will assess some of these objections, and indicate ways to defuse them. In the process,I will also put forward some considerations on the philosophical methodology involved in coming up with a logic of vagueness.

November 06, 2004, 6-7:30 PM in 234 Moses Hall

Alan Hájek (Australian National University)

Two New Paradoxes for Decision Theory

I will present two short papers back-to-back, each presenting a new paradox for decision theory.

  1. “Vexing Expectations” (co-written with Harris Nover), introduces a St.Petersburg-like game in which your pay-offs grow without bound and alternate in sign (rewards alternate with penalties). We can apparently make the game seem as desirable or undesirable as we want ­ even infinitely good and infinite bad ­ simply by reordering the pay-off table, yet the game remains unchanged throughout. We argue that the game is more paradoxical than the St. Petersburg game in several respects and that it shows an important respect in which decision theory is incomplete. I go on to draw some still darker morals.

  2. “The Cable Guy Paradox” presents a situation in which you are certain that you will receive evidence that will make you less confident of a particular proposition than you are now. What, then, are you waiting for – shouldn’t you lower your confidence in that proposition now? Not at all. I parlay this curiosity into a paradox for decision theory. In it, you rationally act in a way that you know is guaranteed to frustrate a future self of yours, without any extenuating circumstances (as we find, for example, in Ulysses and the Sirens). Sometimes it is rational to act against your rationally-formed future preferences, even when you know exactly how to avoid doing so.

November 08, 2004, 6-7:30 PM in 234 Moses Hall

Graham Priest (University of Melbourne, Philosophy)

Intentionality and Non-Existence

The aim of this talk is to outline a semantics for intentional discourse (‘believes’, ‘fears’, ‘worships’, etc.). A central feature of the semantics is its deployment of non-existent objects. Some of the problems to which the notion of a non-existent object is supposed to give rise will also be discussed.

November 24, 2004, 6-7:30 PM in 234 Moses Hall

Kai Frederick Wehmeier (UC Irvine, Logic and Philosophy of Science)

The Lorn Indentity

Even before the notion of objectual identity (as the binary relation that every object bears to itself, and to no others) assumed such a prominent place in the writings of Frege and Russell, David Hume wondered how identity could possibly be a relation, given that it never relates two objects. Three figureheads of analytic philosophy – Frege, Russell, and Wittgenstein – have expressed similar qualms. I will discuss the merits of this “paradox of identity” (which is distinct from Frege’s puzzle concerning informative identity statements) and explore the ramifications of rejecting identity as a binary relation under logical, linguistic, and metaphysical aspects.

December 08, 2004, 6-7:30 PM in 234 Moses Hall

Hannes Leitgeb (Stanford, CSLI)

Under What Conditions Does Carnap’s Quasianalysis Succeed?

We investigate the conditions under which Carnap’s method of quasianalysis in his “Logischer Aufbau” yields adequate results. In particular, we state both necessary and sufficient conditions for the soundness and completeness of quasianalysis. Adequacy is analyzed as the conjunction of soundness and completeness. It is shown that there is no method of (re-)constructing properties from similarity which delivers adequate results in all possible cases if the same set of individuals is presupposed for properties and for similarity and if similarity is a relation of finite adicity. The theory is applied to various examples including an analysis of Russell’s construction of temporal instants and of Carnap’s constitution of the phenomenal counterparts to quality spheres.

February 09, 2005, 6-7:30 PM in 234 Moses Hall

Ulrich Majer (Georg August Universität Göttingen)

Husserl’s Concept of Lebenswelt and Weyl’s ridiculous circle: Reflections about the Crisis of European Science

In his book Die Krisis der europaeischen Wissenschaften und die transzendentale Phaenomenologie Husserl introduced the notion of Lebenwelt as an essential part of the surmounting (Ueberwindung) of the crisis. In my talk I will investigate the origin and significance of Husserl’s notion. In spite of the obscurities inherent to the notion, I have chosen to analyze the notion in a somewhat unusual manner. Instead of presenting an immanent interpretation I choose an external point of view – that of Weyl’s and Hilbert’s approaches to the pretended crisis of science.

February 23, 2005, 6-7:30 PM in 234 Moses Hall

Jonathan Cohen (UC-San Diego, Philosophy)

Color Constancy as Counterfactual

In recent years, vision scientists and philosophers of perception have devoted considerable attention to questions about color constancy. Among the most important issues surrounding color constancy are those about how we should understand the phenomenon and those about what the phenomenon shows about the nature of color. I believe that the phenomenon of color constancy has been misunderstood, and that correcting this misunderstanding will have the effect of undercutting the apparent support the phenomenon provides to accounts of color as illumination-independent properties.

March 09, 2005, 6-7:30 PM in 234 Moses Hall

Michael Glanzberg (UC-Davis, Philosophy)

Context and Unrestricted Quantification

Much of the debate over the possibility of ‘absolutely unrestricted quantification’ – quantification over a domain of ‘absolutely everything’ – has centered on the paradoxes. To some, such as myself, careful consideration of the paradoxes shows absolutely unrestricted quantification to be impossible. But those of us who hold this sort of view face a challenge. For even if we establish on such general grounds that absolutely unrestricted quantification is impossible, we have still to account for the ways that our prima facie unrestricted quantifiers really function. This challenge is made all the more pressing, as Timothy Williamson has recently argued, by the appearance that some applications of quantifiers require them to be absolutely unrestricted. This paper I take up these challenges, by presenting a contextualist approach to unrestricted quantification. I propose that even our widest, syntactically unrestricted quantifiers, are subject to a kind of contextual domain restriction. I show that the kind of quantifier domain restriction needed for the paradoxes is not exactly the same as the more ordinary kind we see in everyday discourse, but it is importantly similar. Like ordinary quantifier domain restriction, we can understand it as the setting of a contextual parameter. The parameters involved in contextual and ordinary cases are distinct, but the pragmatic process which sets them is fundamentally the same. Thus, I argue, the basic pragmatic process of quantifier domain restriction does support a contextualist response to the paradoxes. A working draft of the paper is now on the web, at http://philosophy.ucdavis.edu/glanzberg/contextquant.pdf.

March 30, 2005, 6-7:30 PM in 234 Moses Hall

Chirstopher Hitchcock (Caltech, Philosophy)

Prevention, Preemption, and the Principle of Sufficient Reason

This presentation will take the form of an informal seminar. There will be three parts. In the first part, I will review the use of structural equations and graphical causal models to represent causal structures. In the second part, I will review some attempts by myself, and by Halpern and Pearl, to define ‘token causation’ or ‘actual causation’ within the framework of these causal models. I will also present some problems for these accounts. In the third part, I will try out a new idea, based on a principle I (anachronistically) dub the ‘Principle of Sufficient Reason’. This principle helps to explain the difference between ordinary cases of causation, on the one hand, and cases of prevention and causation by omission on the other hand. I will argue that it also helps us to resolve the problems raised in part two.

April 06, 2005, 6-7:30 PM in 234 Moses Hall

Lionel Shapiro (PITT/UCONN, Philosophy - visiting Berkeley this term)

Making Sense of Circular Concepts

According to Anil Gupta and Nuel Belnap, the “extensional behavior” of ‘true’ matches that of a circularly defined predicate. Besides promising to explain semantic paradoxicality, their general theory of circular predicates significantly liberalizes the framework of truth-conditional semantics. The authors’ discussions of the rationale behind that liberalization invoke two distinct senses in which a circular predicate’s semantic behavior is explained by a “revision rule” carrying “hypothetical information” about the predicate’s extension. Both attempted explanations, I argue, face fundamental objections. I then suggest a radical avenue of response to my critique: the theory may be modified to employ a relativized notion of extension, so as to yield a contextualist semantics in which circularity is construed as a pragmatic phenomenon. I argue that this way of putting some of Gupta and Belnap’s formal machinery to semantic use preserves several of their theory’s attractions as a description of the concept of truth.

April 27, 2005, 6-7:30 PM in 234 Moses Hall

Alison Gopnik (UC Berkeley, Psychology)

Babies and Bayes Nets: Theory Formation in Scientists and Children

For some time, I’ve argued that scientists may employ powerful natural learning mechanisms that were first designed for children’s learning - my motto is that children are not little scientists but that scientists are big children. In this talk I outline a more precise cognitive and computational account of such mechanisms. I propose that children employ specialized cognitive systems that allow them to recover an accurate “causal map” of the world: an abstract, coherent, learned representation of the causal relations among events. This kind of knowledge can be perspicuously understood in terms of the formalism of directed graphical causal models, or “Bayes nets,” which was first employed as a normative account of causal inference in science. Children’s causal learning and inference may involve computations similar to those for learning causal Bayes nets and for predicting with them. Experimental results suggest that 2- to 4-year-old children construct new causal maps and that their learning is consistent with the Bayes net formalism.