Fortunately for those of us who work on the topic, Ernie Sosa has devoted much of his (seemingly inexhaustible) intellectual energy to the problem of philosophical skepticism. And to great effect. With the three exceptions of Peter Unger, whose 1975 Ignorance: A Case for Scepticism is a grossly under-appreciated classic of epistemology; Timothy Williamson, whose 2000 Knowledge and its Limits is, I hope, on its way to being a less underappreciated classic; and Thomas Reid, I have benefitted more from Sosa’s (...) wrestlings with skepticism than from anyone else’s work on the topic. (shrink)

Externalism about some mental property, M, is the thesis that whether a person (or other physical being) has M depends, not only on conditions inside the person.

He then argues that (1), (2) and (3) constitute an inconsistent triad as follows (1991, p. 15): Suppose (1) that Oscar knows a priori that he is thinking that water is wet. Then by (2), Oscar can simply deduce E, using premisses that are knowable a priori, including the premiss that he is thinking that water is wet. Since Oscar can deduce E from premisses that are knowable a priori, Oscar can know E itself a priori. But this contradicts (3), (...) the assumption that E cannot be known a priori. Hence (1), (2), and (3) are inconsistent. McKinsey’s conclusion is that ‘anti-individualism is inconsistent with privileged access’ (ibid.). (shrink)