Abstract

Thinking is a convention-involving process in that just as there are certain activities that count as touchdowns or checkmates, so too there are certain activities that count as presuming or supposing for the sake of argument. The activities that are constitutive of mental states are often overt acts of speech, and thus felicitous utterance of a sentence such as 'I presume that A' is, to borrow a term from J. L. Austin, a performative. The performativity of attitude avowals in turn implies that an individual's cognitive status does not supervene just upon the physical goings within her skin, for it implies that whether a person $\phi$'s that A or $\Psi$'s that A, where $\phi$ and $\Psi$ are distinct psychological attitudes, can vary just with variations in that person's social milieu. More broadly, the performativity of psychological-attitude avowals implies the conventionality of psychological attitudes. ;This line of reasoning draws heavily upon the notion of the illocution, or speech act, and a new theory of illocutions is developed. Illocutions are here seen as, centrally, means of engendering commitments to various types of content. We allow for distinctions along the dimension of mode of commitment to countenance the difference between, say, commitment to a content as a supposition and commitment to that content as an assertion. We also allow for variation along the dimension of degree of commitment, and, to distinguish among commitment to questions, propositions, and plans of action, for differences in the kind of content to which commitment is had. The theory is applied to the interaction of speech acts and time, and to the laying of a new foundation for the account of conversational implicature.