Abstract

According to ‘internalism’, what it is rational for me to think at a given time depends purely on the internal mental states and events that are present in my mind at that time. Intuitively, internalism is compelling. But should we trust the intuition? What is the distinction between ‘internal’ and ‘external’ here? Don’t parallel intuitions establish controversial doctrines in the philosophy of mind, like the existence of ‘narrow content’? Why would this intuition be true? This chapter answers these questions. Internalism is true because we need to have norms that we can follow _directly_ (not by reasoning about those norms, or by any more complex process of reasoning at all); and the only norms that we can follow directly in this sense at a given time are ones that supervene on the internal mental states and events that are present in our minds at (or shortly before) the time.