Internalism and externalism in epistemology

1. Forms of the distinction

Although this entry is restricted to epistemology, the terms ‘internalism’ and ‘externalism’ are also used to mark distinctions in ethics and philosophy of mind (see Content: wide and narrow; Moral motivation §1). Within epistemology itself the terms are used variously. The most basic distinction is between views concerning the epistemic justification of belief and views concerning knowledge. As applied to either, internalism is construed variously – for example, as the irreducible normativeness of justification (knowledge), and as the view that justification or knowledge always depends on the subject’s belief system. The most common understanding, however, is Access Internalism – the view that only what is cognitively accessible to the subject in some strong fashion can have any bearing on justification. We may think of externalism as simply the denial of this restriction. Strong cognitive access to a fact is variously conceived; the most common version is that the fact be ascertainable by the subject just by reflecting on the matter. If my justified belief that Susie is in Panama is to justify my belief that she will not be at the meeting tonight, then it must be that I can ascertain by armchair reflection that I justifiably believe that she is in Panama (Ginet 1975: 34; Pollock 1986: Ch. 5, §4.1 offers a quite different way of thinking of the internalist requirement.) Note that this constraint does not require that individuals actually have the knowledge that the alleged justifier obtains, but only that they be capable of acquiring it on reflection.

A crucially important, but usually ignored, distinction is between access to the justifier and access to the epistemic efficacy of the justifier. Consider the perceptual belief that there is snow in front of my house. The justifier, let us say, is my visual presentation as I look out the front window. That would seem unproblematically to satisfy the internalist constraint. But in order for me to know that the belief is justified, it is not enough that I know that my current visual presentation is of such-and-such a character. I must also know that this presentation suffices to justify the belief (that it possesses that ‘justificatory efficacy’). And it is far from unproblematic that this is accessible just on reflection. Indeed, many philosophers have struggled in vain to show that our ordinary perceptual beliefs about the immediate environment are justified by the sensory experiences on which they are typically based. As we shall see, the most common arguments for accessibility internalism give equal support to both kinds of internalist constraint. If one advocates only one kind, we have a mixed view of the sort to be described below.