 This assumption seems hard to deny in the face of such abstract pursuits as algebraic topology, quantum field theory, population biology, modal metaphysics, or twelve-tone musical composition, all of which seem transparently to involve precisely such autonomous applications of human intelligence. Even if there are evolutionary influences behind our general tendency to engage in certain kinds of mental activity, or behind some of our motives in these pursuits (e.g., if a given musician or poet is motivated to compose music or poetry in order to impress a potential mate), this would not show that the activity is governed in its details by such influences (cf. Buchanan and Powell 2015, 2018, and 2019). And again, this assumption of autonomy is borne out in our normal explanations of beliefs such as P above: we take a person at her word that what explains her believing P, for example, is that due to philosophical arguments she’s read and has found convincing she takes ‘water’ to work like a proper name and thinks that it follows from this that ‘water’ refers to whatever molecular compound it picks out in the actual world in all possible worlds in which the compound exists.