Some Remarks on Jerry Fodor's Arguments for a Language of Thought

The arguments that Fodor (1987: 150-52) gives in support of a Language of Thought are apparently straightforward. (1) Linguistic capacities are "systematic", in the sense that if one understands the words 'John loves Mary' one also understands the form of words 'Mary loves John'. In other words, sentences have a combinatorial semantics, because they have constituent structure. (2) If cognitive capacities are systematic in the same way, they must have constituent structure also. Thus there is a Language of Thought. The essential connection between language and thought that the argument requires is: Since the function of language is to express thought, to understand a sentence is to grasp the thought that its utterance standardly conveys. So from the systematicity of sentences it follows that anyone who can grasp the thought that John loves Mary can grasp the thought that Mary loves John. Thought must be as systematic as language, for the best empirical explanation of the psychological fact that one who grasps the thought that John loves Mary can grasp the thought that Mary loves John is that grasping a thought is standing in some thinking relation to a complex entity whose constituents are MARY, X LOVES Y, and JOHN and semantic relations among MARY, X LOVES Y, and JOHN. So sayeth Fodor (1987).