Wednesday, September 30, 2009

Critical Notice of Mark Wilson's Wandering Significance

I have posted a long critical notice of Mark Wilson's amazing book Wandering Significance: An Essay on Conceptual Behavior. It will eventually appear in Philosophia Mathematica. My impression is that even though the book came out in 2006 and is now available in paperback, it has not really had the impact it should in debates about models and idealization. I think this is partly because the book addresses broad questions about concepts that don't often arise in philosophy of science or philosophy of mathematics. But if you start to read the book, it becomes immediately clear how important examples from science and mathematics are to Wilson's views of conceptual evaluation. So, I hope my review will help philosophers of science and mathematics see the importance of the book and the challenges it raises.

Tuesday, September 15, 2009

Cole's Practice-Dependent Realism and Creativity in Mathematics

Julian Cole's "Creativity, Freedom and Authority: A New Perspective on the Metaphysics of Mathematics" is now available via the Australasian Journal of Philosophy. Cole develops what seems to me to be the most careful version of a social constructivist metaphysics for mathematics. Basically the idea is that the activities of mathematics constitute the mathematical entities as abstract entities. This makes it coherent for Cole to insist that the entities have many of the traditional features of abstract objects such as being outside space and time and lacking causal relations. Crucially for the causal point, even though the mathematicians constitute the mathematical entities, they do not cause them to exist.

One consideration in favor of his view that Cole emphasizes is the creativity that mathematicians have to posit new entities. Qua mathematician, he notes "the freedom I felt I had to introduce a new mathematical theory whose variables ranged over any mathematical entities I wished, provided it served a legitimate mathematical purpose" (p. 589). Other mathematicians have of course said similar things, from Cantor's claim that "the essence of mathematics lies precisely in its freedom" (noted by Linnebo in his essay in this volume) and Hilbert's conception of axioms in his debate with Frege.

I have two worries with this starting point. First, is it so clear that mathematicians really have this freedom? The history of mathematics seems filled with controversies about new objects or new mathematical techniques that seem to presuppose the existence problematic objects. Second, even if mathematicians have a certain kind of freedom to posit new objects, how do we determine that this freedom is independent of prior metaphysical commitments? One option for the traditional platonist or the ante rem structuralist is to insist that mathematicians are now free to posit new objects only because it is highly likely that these new objects can find a place in their background set theory or theory of structures. This of course would not settle the issue against practice-dependent realism, but it gives the realist a strategy to accommodate the same data.

Wednesday, September 9, 2009

Call for Papers: Mathematical and Scientific Philosophy

Readers of this blog should check out the fall meeting of the Indiana Philosophical Association:

Call for Papers

Mathematical and Scientific Philosophy

with a special session on the Darwin Bicentenary

Indiana Philosophical Association Fall Meeting
Invited Speakers: Colin Allen, Elisabeth Lloyd, Larry Moss

Saturday AND Sunday, 5-6 December 2009
Indiana Memorial Union, IU Bloomington

We invite submissions—from philosophers, logicians, and historians and philosophers of science—on topics that fall under the theme of the meeting. Papers should be 35 minutes reading time, i.e., no more than 17 double-spaced pages. Papers will be blind reviewed; the author’s name and affiliation should therefore appear only on the cover sheet.

Send one copy of your paper and a short, one–paragraph abstract to one of the following.

Peter Murphy
Department of Philosophy
Esch Hall 044U
University of Indianapolis
Indianapolis, IN 46227
murphyp at

Bernd Buldt
Department of Philosophy
CM 21 026
Fort Wayne, IN 46805
buldtb at

Charles McCarty
The Logic Program
Sycamore Hall
Indiana University
Bloomington, IN 47405
dmccarty at

Electronic submissions of papers and abstracts in MSWord or pdf formats are encouraged.
Deadline for Submissions: 15 October 2009
Deadline for Notifications: 9 November 2009
For further information, please email Charles McCarty at dmccarty at

Tuesday, September 8, 2009

Krugman on Mathematics and the Failure of Economics

Probably anyone who is interested in this article has already seen it, but Paul Krugman put out an article in Sunday's New York Times Magazine called "How Did Economics Get It So Wrong?". The article is very well-written, but a bit unsatisfying as it combines Krugman's more standard worries about macroeconomics with a short attack on financial economics. I am trying to write something right now about the ways in which mathematics can lead scientists astray, and one of my case studies in the celebrated Black-Scholes model for option pricing. Hopefully I can post more on that soon, but here is what Krugman says about it and similar models which are used to price financial derivatives and devise hedging strategies.

My favorite part is where Krugman says "the economics profession went astray because economists, as a group, mistook beauty, clad in impressive-looking mathematics, for truth". But he never really follows this up with much discussion of the mathematics or why it might have proven so seductive. Section III attacks "Panglossian Finance", but this is presented as if it assumes "The price of a company's stock, for example, always accurately reflects the company's value given the information available". But, at least as I understand it, this is not the "efficient market hypothesis" which underlies models like Black-Scholes. Instead, this hypothesis makes the much weaker assumption that "successive price changes may be considered as uncorrelated random variables" (Almgren 2002, p. 1). This is the view that prices over time amount to a "random walk". It has serious problems as well, but I wish Krugman had spent an extra paragraph attacking his real target.

Almgren, R. (2002). Financial derivatives and partial differential equations.
American Mathematical Monthly, 109: 1-12, 2002.