I’m sharing for comments a paragraph from Radical epistemology, structural explanations, and epistemic weaponry by Richard Pettigrew. PDF. The context is trying to understand what justifies beliefs as knowledge.
The debate between these two camps is often set up with internalism as an extreme position that says that only internal states of a subject are relevant to whether their beliefs are justified, while externalism is just the negation of internalism, covering any view that takes any external state to be in any way relevant. But I think it’s more illuminating to array the various positions across a landscape that has extreme internalism at one edge of the map, extreme externalism at the opposite edge, and all other positions spread out in between them. Where you lie in this landscape is determined by the extent to which the conditions that suffice for and are required for justification concern matters internal to the subject who has the belief and the extent to which they concern matters external to them. Perhaps the most extreme internalist position says that whether or not you are justified in believing something at a given time depends only on those of your mental states that occur at that time and that you actually access at that time. And the most extremely externalist position says that a belief is justified just in case it is true. In between, we have a large array of positions. We have what Conee and Feldman (2001) call mentalism, which allows mental states that are not only not actually accessed but also not accessible to help determine whether a belief is justified. And we have process and indicator reliabilism, both of which appeal to an internal state—the belief-forming process, or the grounds of the belief—but consider mainly external features of those internal states—the proportion of the beliefs that the process produces that are true, or the objective probability that the belief is true given that the subject has that ground for it (Goldman, 1979; Alston, 1988). And there are many more.