The Nature of Symbols in the Language of Thought1

The core of language of thought program is the claim that thinking is the manipulation of symbols according to rules. Yet LOT has said little about symbol natures, and existing accounts are highly controversial. This is a major flaw at the heart of the LOT program: LOT requires an account of symbol natures to naturalize intentionality, to determine whether the brain even engages in symbol manipulations, and to understand how symbols relate to lower-level neurocomputational states. This paper provides the much needed theory of symbols, and in doing so, alters the LOT program in significant respects. According to the Classical Computational Theory of the Mind (simply called, ‘CTM’), expressions in the language of thought will play a key role in a completed scientific theory of mind. For thinking is supposed to be a computational process involving the manipulation of symbols in the language of thought (or ‘LOT’). However, as central as LOT symbols are to the CTM program, it has long been observed that the proponents of LOT have yet to provide a plausible account of the nature of primitive expressions in the language; that is, it is claimed that LOT lacks a defensible condition on the type individuation of such expressions. It is fair to say that without a plausible theory of the 1Address for correspondence: 423 Claudia Cohen Hall, University of Pennsylvania 249 South 36th Street Philadelphia, PA 19104-6304 Email: [email protected] s . Thanks very much to Jerry Fodor, who’s work inspired this project, for his helpful comments on various drafts of this essay and for numerous heated debates on this topic. Thanks also to the following audiences for comments on this paper: the departments of philosophy at the University of Cinncinatti, Temple University, and the University of Maryland, the cognitive science department at Lehigh University, the audience at the ESPP/SPP joint meeting in Barcelona, and the audience at the Central APA in Chicago. Special thanks to an anonymous reviewer at this journal, Gordon Bearn, Mark Bickhard, John Bickle, Peter Carruthers, Margaret Cuonzo, Cris Gauker, Kirk Ludwig, Tom Polger, Jesse Prinz, Gualtierro Puccinnini, Gary Hatfield, Georges Rey, Bill Robinson and Gerald Vision for helpful discussions and/or written comments. And thanks very much to Murat Aydede for his helpful reply at the APA