Simply stated, the language-of-thought thesis (LOT) holds that thinking (i.e., cognition) is carried out in a languagelike medium, where the thoughts that constitute thinking are themselves sentencelike states of the thinker. Since the demise of philosophical behaviorism in the early 1960s the LOT thesis has enjoyed considerable support as a central tenet of a more encompassing representationalist theory of mind (RTM). Proponents of RTM, led by Jerry Fodor, have mounted a sustained defense of LOT.

RTM offers an account of propositional attitudes—beliefs, desires, doubts, and so on—according to which propositional attitudes relate the possessor of the attitude to a mental representation (cf. Fodor 1981). Mental representations have both semantic and physically realized formal properties: They are semantically evaluable (e.g., as being true or false, as being about or referring to certain entities or properties); they stand in inferential relations to other...