 This “golden triangle” of constitutive relations generates a distinctive rationalist account of meaning. To be competent with an expression’s meaning is to be in an internal cognitive state that puts one in a position to identify its extension in any possible world on the basis of apriori reflection alone. Apriori reflection will also suffice to determine whether two expressions are associated with the same or different meanings. This rationalist approach to meaning contrasts with the empiricist one: whereas the empiricist uses causally efficacious cognitive mechanisms to isolate the reference-fixing criteria currently associated with an expression, the rationalist uses the subject’s ideally rational judgments to isolate the complex cognitive states that would ground those reflective judgments. As a consequence, the aspect of understanding that corresponds to a rationalist meaning may turn out to be more heterogeneous and less stable than the shared, causally efficacious ‘templates’ postulated by the empiricist. The “golden triangle” also involves a distinctive rationalist account of modal epistemology, according to which ideal apriori conceivability is a fail-safe guide to metaphysical possibility. This modal rationalism affords a simple and attractive account of our access to modal facts (Chalmers 1996, 136–8; 1999, 488–91;  2002a).[15]