Abstract

Two naturalistic explications of propositional attitudes and their contents are distinguished: the language of thought based theory, on which beliefs are relations to sentences in the language of thought; and the propositional attitude based theory, on which beliefs are functional states of a functional system that does not imply a language of thought, although consistent with it. The latter theory depends on interpersonally ascribable conceptual roles; if these are not available, the language of thought theory has the advantage. But the propositional attitude based theory explains intentionality and conceptual structure as well as the language of thought based theory, and it has two further advantages. First, it does not make the existence of beliefs and desires depend on the language of thought hypothesis. Secondly, its employment of interpersonally ascribable conceptual roles permits a theory of truth conditions to meet certain desiderata, such as a social basis for truth conditions, and a realist conception of truth.