46th annual lecture series, 2005-06

Perception and Its Objects
Bill Brewer, University of Warwick, Philosophy
Friday, 16 September 2005, 3:30 p.m.
2500 Wesley W. Posvar Hall

Abstract:  It is widely accepted that the argument from illusion establishes a
conditional conclusion along the following lines. If the subjective nature
of perceptual experiences is supposed to be characterized directly by the
natures of the objects presented in such experiences, then those 'direct
objects' must be mind-dependent. This leads most theorists to reject the
antecedent, and move to a characterization of the subjective nature of
experiences in terms of their representational content. I argue that this is
a mistake. It is perfectly compatible with the existence of various
'illusions' to characterize perceptual experiences by their mind-independent
objects. Content only enters the characterization of perception as a result
of an intellectual abstraction from the nature of these basic experiences
themselves.

Darwin on Orchids: Teleology with a Twist
John Beatty, University of British Columbia, Philosophy
Friday, 30 September 2005, 3:30 p.m.
2500 Wesley W. Posvar Hall
Reception honoring Jim Lennox to follow

Testing Newton, Then and Now
George Smith, Dibner Institute, MIT
Friday, 11 November 2005, 3:30 p.m.
2500 Wesley W. Posvar Hall

Abstract: In eschewing the "method of hypotheses," Newton's Principia dictated a less than obvious form of testing of his theory of gravity across the centuries after he published it. In particular, comparisons of calculated orbital motions with observation cannot serve directly to test the theory, but instead address the question, what forces beyond those taken into account in the calculation are affecting the motions? The test of gravity theory then centers on whether robust physical sources can be found for the discrepancies between calculated motions and observation. The talk will examine first why the Principia forced this logic of testing on gravity research and second how such testing played out both before and after the discovery of the anomalous precession of Mercury's perihelion and Einstein's new theory of gravity. The principal conclusion will be that the evidence for gravity theory produced by research in celestial mechanics and physical geodesy has been far stronger than generally recognized; this in turn has implications about the relationship, logical and historical, between Newton's and Einstein's theories.

The Rise and Fall of Panselectionism ::: wav audio file, 22 MB
Michael Dietrich, Dartmouth College, Biological Sciences
Friday, 9 December 2005, 3:30 p.m.
2500 Wesley W. Posvar Hall

The Philosophy of Ptolemaic Astronomy
Bernard R. Goldstein, University Professor Emeritus
University of Pittsburgh
Religious Studies and History & Philosophy of Science
Friday, 20 January 2006, 3:30 p.m.
2500 Wesley W. Posvar Hall

Abstract: Claudius Ptolemy, who lived in Alexandria in the second century AD, was without doubt the most important astronomer in antiquity. My focus will be on his methodology, but I will begin with a brief discussion of the topics in his best known work, the Almagest, because it is often summarized in a few sentences that do not do justice to its contents. Among the characteristic features of Ptolemy’s astronomy that set his work apart from that of any other ancient Greek are: (1) his notion of reliability as it relates to specific dated observations, including those by Ptolemy himself; (2) his explicit derivations of the parameters for his models from the stated observations by methods that can easily be applied to other observations; and (3) his appeal to mean motions (not to be confused with uniform motions), and divergences from these mean motions, in determining the true positions of the planets, based on theological commitments. These and other features of Ptolemy’s astronomy will be explained and put in their appropriate ancient context.

Computers and the Future of Mathematical Proofs ::: mp3 audio file, 10 MB
Thomas Hales, University of Pittsburgh, Mathematics
Friday, 24 February 2006, 3:30 p.m.
2500 Wesley W. Posvar Hall

Abstract:  It is relatively common for the mathematical proof of a single theorem to run hundreds or even thousands of pages.  It has also become common for mathematical proofs to rely on computer-assisted calculations.  An editor of one of the most prestigious mathematical journals has recently declared that it has become impossible to find peers who are willing to review computer code.  As a result, the journal has started to publish theorems without any meaningful review of the underlying computer code.  What do these developments mean for computers and the future of mathematical proofs?

Hunting Causes and Using Them ::: mp3 audio file, 11 MB
Nancy Cartwright, London School of Economics and
University of California, San Diego, Philosophy
Friday, 24 March 2006, 3:30 p.m.
G-8 Cathedral of Learning

Abstract:  Causation is a big topic in philosophy of science  nowadays, as well as in a number of the sciences themselves, with at least a dozen different 'theories of causation' on offer, all of them with strong arguments on their side. This talk will focus on recent offerings in philosophy and in economics. It will argue that, unfortunately, these theories of causality are not theories after all. We expect of a theory both that we be able to test it and that we be able to put the good theory that has passed tests to use.The trouble with theories of causality in both philosophy and in economics is that they are good --too good indeed-- at either one or the other of these and almost incapable of the other: We can either hunt cause or use them, but not both. That means we need better theories -- or rather, different kinds of theories.

Unification and Explanation: A Case Study From Real Algebraic Geometry
::: mp3 audio file, 14 MB
Paolo Mancosu, University of California, Berkeley, Philosophy
Friday, 21 April 2006, 3:30 p.m.
817R Cathedral of Learning

Abstract:  Philip Kitcher proposes a model of scientific explanation, including explanations in mathematics, in which unification plays a constitutive role. On his view unification consists in a deductive systematization of our scientific beliefs.  More precisely, it amounts to taking a minimal number of types of facts as basic and deriving from them all of the remaining varied phenomena by relying on the same patterns of derivation again and again.  Science advances our understanding and thus explains by providing unifications of this kind.  This account of explanation as unification, however, has difficulties accounting for certain explanations which occur in mathematical practice.  An interesting case in this respect is algebraic geometry. The elementary theory RCF of real closed fields represents a unification of many scattered theorems which are proved within different real closed fields, like the real numbers or the complex numbers, and which may be established in their respective domains by completely different methods, e.g. topological or function theoretic. The completeness of RCF gives rise to a transfer principle: if an elementary sentence S holds in one real closed field, then it holds in every real closed field. Moreover, because of the decision method for RCF due to Tarski and Seidenberg the truth of S in some such field implies the existence of an elementary proof of it within RCF by which S gets established uniformly for all real closed fields no matter how it was proved originally. Although the said transfer principle is a powerful tool Gregory W. Brumfiel in his work on semi-algebraic sets emphatically rejects its employment in proofs because such proofs, he argues, fail to explain their result. Instead he aims at proofs that may use non-elementary methods yet work uniformly for all real closed fields and, for that matter, exhibit a "natural" uniformity which is in general not the case for proofs within RCF (provided it is even physically feasible to actually work those out). Hence the upshot of this case study is that Kitcher's model of explanation - even assuming it is indeed on the right track - doesn't tell the whole story yet.  In general there is more to explanations than unification.