Content Externalism and Self-Knowledge

There appears to be a tension between two widely held philosophical theses: content externalism and what is often called “privileged access”. The first is the metaphysical thesis that the contents of many propositional attitude-types are at least partially determined by properties external to the thinking subject. The second is the epistemological thesis that we have a priori access to the contents of our own propositional attitudes. Those who hold that at least one of these theses must be false are called incompatibilists. My goal is to show that the incompatibilists are wrong, that content externalism and privileged access can both be true.

In Chapter 1, I briefly introduce content externalism and review the source of the alleged tension between the latter and privileged access. In Chapter 2, I address the so-called “discrimination argument” for incompatibilism. This argument appeals to the fact that, if content externalism is true, then we will not always be able to discriminate one thought-type from another. This generates problems for privileged access if we think that knowledge requires the ability to discriminate between relevant alternatives. I argue, however, that knowledge does not require such an ability. In Chapter 3, I address Jessica Brown’s "illusion argument” for incompatibilism. While this argument might show that singular externalism is incompatible with privileged access, I argue that it does not generalize to other forms of content externalism. In Chapter 4 I evaluate Boghossian’s “memory argument”. First, I draw on existing criticism to show that the original 1989 version of the argument fails because it relies on false premises about memory. I then consider and reject the possibility, originally proposed by Sanford Goldberg, that the argument can be reconstructed without these false premises. Finally, in Chapter 5, I discuss and evaluate McKinsey’s reductio. First, I argue that the externalist cannot be expected to accept the closure principle on which McKinsey relies. Second, I argue that though the compatibilist may be committed to the apriority of certain environmental propositions, these propositions are modest enough that it is not obviously absurd to suppose that they might be a priori.