Externalists reject any such view. I think that the idea that we can tell, simply by way of reflection, whether our beliefs are justified, is deeply commonsensical. More than that, the idea that responsible epistemic agents ought to reflect on their beliefs, and hold them only if they somehow pass muster, is utterly natural.
Hilary KornblithBealer has a number of reasons for thinking that a naturalistic epistemology is self-undermining. Let me focus on one of these. (I've tried to take on all of them in the first chapter of Knowledge and Its Place in Nature.)
Hilary KornblithMy own reasons for favouring talk of natural kinds is just that I believe the best accounts of the success of scientific theories presupposes the existence of natural kinds.
Hilary KornblithIn my view, since the case can be made that knowledge too is a natural kind, the role of pretheoretical intuitions is similarly diminished in epistemology.
Hilary KornblithWhen I think about discussions at the Society for Philosophy and Psychology, a group which includes not only philosophers and psychologists, but also computer scientists and linguists, it is noteworthy that one can't always tell just from the content of particular contributions from the audience, whether a given questioner is a philosopher or an empirical scientist.
Hilary KornblithThe worry that unreflective belief acquisition may be unreliable, after all, applies equally to reflective belief acquisition: it too may be unreliable. To my mind, the plausibility of internalist views about justification is dramatically decreased when one becomes vividly aware of what introspection and reflection actually achieve.
Hilary Kornblith