May 15, 2005

**Mathieu Marion** (UQAM)

“Anti-Realism, Reasons and Games”

**Chungh Young Lee** (Minnesota)

“The Modal Interpretation of Quantum Mechanics and Proper Mixtures”

Comments: Ori Belkind

Abstract:The modal interpretation proposed by Dennis Dieks and Pieter Vermaas (and its variants) should treat proper and improper mixtures differently. Two ways of applying their modal rule to proper mixtures are distinguished, depending on whether or not the ignorance interpretation is applied, and shown to yield different property ascriptions, even when the proper mixtures in question result from mixing orthogonal states without degeneracy. And such different property ascriptions give rise to empirical disparities. Implications of this distinction on the recent attempts to refute the Vermaas and Dieks’ modal rule are discussed.

**Tom Lockhart **(Chicago)

“The Insufficiency of Neo-Fregean Logical Segmentation”

Comments: Greg Andres

Abstract:‘Frege’s Theorem’ inspires the ‘neo-Fregean logicism’ of Bob Hale and Crispin Wright. Their version of logicism requires the claim that if some speaker unfamiliar with number language is told that Hume’s Principle is true then that speaker could derive a mastery of numerical terms, and in particular conclude that numbers are objects. This in turn calls for a means to “discriminate proper names from expressions of other kinds” using “clear and exact criteria, relating to their functioning within language” (Dummett 1981, p. 58). I argue not only that the criteria developed by Hale are not sufficient to do the work required of them but also that we should not expect further refinements of the criteria to succeed. My argument is that Hale and Wright assume that natural language is in essence as syntactically perspicuous as abegriffsschrift. I think this is false. I further suggest that Hale and Wright are not in fact following Frege in this project, and that this indicates that Frege’s logicism might be different in spirit that Hale and Wright’s.

**Tracey Lupher **(Texas, Austin)

“Who Proved Haag’s Theorem?”

Comments: Sona Ghosh

Abstract:In the physics literature, there are several different characterizations of Haag’s theorem and its consequences for quantum field theory. These different versions of Haag’s theorem are due in part to various generalizations and more”rigorous” proofs of Haag’s theorem as well as to the fact that many of these proofs were done using different formulations of quantum field theory. As a result, there is confusion about what Haag’s theorem is and when it was proved. This paper clears up some of this confusion by examining the history and development of Haag’s theorem up to 1959. It is argued that the question of who proved Haag’s theorem is tied up with what the theorem is taken to show.

**Daniel Parker** (Maryland)

“Boltzmann Entropy: What is it Good For?”

Comments: Dylan Gault

Asbtract:Absolutely nothing. In this paper, I argue that the Boltzmann entropy fails to meet some minimal requirements for a successful reduction of thermodynamics to statistical mechanics. The Boltzmann entropy does not provide a clear and unambiguous way of linking the thermodynamic entropy to statistical mechanics due to the fact that the entropy is relative to a chosen description. Further, it precludes explaining the success of thermodynamics by appealing to its putatively reducing theory. This conception of entropy creates confusion rather than solving problems.

**Mike Tamir** (Pittsburgh)

“Explanation Without Reification”

Comments: Robert Moir

**Book Prize (Presented by William Harper)**

Abstract:This paper investigates Bob Batterman’s treatment of the phenomena of rainbow formation and phase transitions. Both examples are cases in which Batterman claims that there is a critical breakdown in intertheoretic accounts of the phenomena, leading to highly complicated explanatory results. Batterman’s account of these situations has recently generated concern over the ontological commitments involved in maintaining the robustness of his explanations. I claim that a clear appreciation of Batterman’s philosophical agenda and a careful juxtaposition of each of these examples will help to shed new light on the sort of ontological commitments required for a complete understanding of the phenomena. I conclude from this discussion that though Batterman’s technique of appealing to gross idealization in developing the sorts of explanations he desires is not in principle unfeasible, such techniques can fail and must consequently be employed with great caution.

Greg Andres, Elana Geller, David Johnston, Robert Moir