Abstract

Psychological externalism is the thesis that the contents of many of a person's propositional mental states are determined in part by relations he bears to his natural and social environment. This thesis has recently been thrust into prominence in the philosophy of mind by a series of thought experiments due to Hilary Putnam and Tyler Burge. Externalism is a metaphysical thesis, but in this work I investigate its implications for the epistemology of the mental. I am primarily concerned with the question whether externalism undermines the idea that a person typically knows the contents of her own thoughts, beliefs, and other propositional attitudes directly and authoritatively. I criticize arguments that have been advanced on behalf of a positive answer to this question, and argue that they rest on a faulty conception of the nature of first person authority, one which likens our access to our own minds to perception. An account of the basis of first person authority is sketched that locates our epistemic right to our self-ascriptions of propositional attitude not in our ability to discriminate among the various thought contents we might be thinking, but rather in our ability to express our thoughts, and to think with them in accordance with the norms of rationality. I consider also the question whether first person authority and externalism jointly make possible a refutation of certain forms of global skepticism, as has been famously argued by Putnam. I argue that Putnam's attempted refutation fails, because the crucial externalist claims that drive it are not knowable a priori