Suppose you know p and that you have an internal duplicate that believes p for roughly the same reasons. A commonly held intuition is that you and your duplicate are justified in believing p to the same degree. Suppose that’s right. A commonly drawn lesson is that justification supervenes on the intrinsic properties of a thinker. Suppose that’s right. A commonly drawn lesson is that the justification of our beliefs is determined by these intrinsic properties. That might be a mistake. Even if two intrinsic duplicates cannot have beliefs that differ in justificatory status, someone might say that the reason that the second subject is justified is that the second subject is an intrinsic duplicate of someone who has knowledge. That property might supervene on the intrinsic properties but there’s a perfectly good sense in which that property isn’t determined solely by that individual’s intrinsic properties. Suppose you hold the view that to be blameless before the law you don’t have to act like a lawful citizen, you only have to be motivated in the way that lawful citizens are. Maybe I intend to drive on the left and I have a very similar twin that intends to drive on the right. Whether one of us is the same on the inside as a lawful citizen depends (in part) upon the traffic regulations. Nevertheless, anyone who is just like the one of us that intends to drive on the correct side of the road is blameless before the law but only if they are the same on the inside as the one who intends to do something that is ‘turns out’ to be consistent with the regulations.
This might seem to be a minor point, but I think it matters in the epistemology of moral judgment. Someone might think that NED intuitions support the phenomenal conservative view that says that your judgment that p is true is justified if it seems that p is true and there’s no reason to think things are amiss. They don’t, however. Suppose someone’s moral judgment is based on an intuition where it could not be that the moral world is the way that the intuition makes it seem. According to PC, as long as they have no reason to think things are amiss it seems that the moral judgment based on the intuition is justified. According to externalism with supervenience internalism (ESI), that doesn’t follow. The person who has the sort of intuitions that lead to cannibalism isn’t the same on the inside as someone who knows what to do when trying to decide what to hunt up for dinner.
[Juan and I discussed this point earlier when I wasn't so sleepy and he has made a similar point in his Phil Perspectives paper.]