I was thinking last night about the new show Once Upon a Time, and it occurred to me that it might provide a really good illustration of the difference between externalism and internalism in epistemology. (I haven't seen last night's episode yet, so please no one spoil it for me.)
Internalism holds that what justifies our beliefs or makes them rational or what grounds our knowledge must be something internal to our thinking, in other words something where the reasons why it is justified, rational, or grounded are accessible to our conscious thought. We have to be able to see why our beliefs are grounded for those beliefs to be grounded. We have to be aware of what makes it a good belief for it to be a good belief. It wouldn't be enough to have reliable belief-forming mechanisms (such as senses that reliably give me the right information).
Externalism holds that there might be things make our beliefs justified or rational or grounding our knowledge that are not accessible to our conscious thought. We don't have to be aware of what justifies us in thinking something for it to be a justified belief. For it to be well-grounded knowledge, we don't have to know that our knowledge is grounded in reliable practices and thus why it is well-grounded knowledge. It just has to be grounded in the right sort of ways.
Perhaps the biggest place of disagreement comes over how to respond to skepticism. If internalism is true, I would have to prove that my senses are reliable for them to ground my knowledge, which of course I can't do, because I might be in a virtual reality for all I can know by internalist standards. There are internalists would would disagree, but a lot of philosophers have concluded that internalism leads hopelessly to skepticism, because I can't prove that my senses are reliable, and just having reliable senses isn't enough. I'd have to be able to prove it, which I can't do. But externalism can handle skeptical arguments by pointing out that I can know all sorts of stuff even without being able to prove it. It doesn't mean I can prove I know things. It just means that skeptical arguments fail, because the skeptic has to show that my senses are unreliable to show that I don't know things. With internalism, all the skeptic has to show is that I don't know if my senses are unreliable. With externalism, the skeptic has to show that they are in fact unreliable. So the burden of proof on the skeptic is higher with externalism.
Once Upon a Time provides a nice illustration of externalist epistemology. The basic premise of the show is that the Evil Queen has cursed all the characters in the Enchanted Forest by bringing them to a terrible place where there are no happy endings except for her. That terrible place is Storybrooke, Maine, in a world otherwise very much like our current day. The Evil Queen is the mayor. The story shifts back and forth between events in the characters' lives back in the Enchanted Forest and events in their lives now in Storybrooke, where no one is supposed to remember their previous lives except the Evil Queen.
Snow White and Prince Charming are the Evil Queen's primary targets. She wants revenge against Snow White for something we haven't seen yet (as least as of last week's episode). She wants to ensure that they are not together. They have no memory of each other, certainly not of having been married to each other. He was in a coma when the show began, and apparently he had been since the curse began. She has no memory of him. When he awakes from his coma, he has no memory, until the Evil Queen at some point seems to have interfered to give him memories of being married to someone else, someone who turns out to have been engaged to him in the Enchanted Forest before he broke it off to marry Snow White. But when they meet up, they feel such a longing for each other, as if they have always been meant to be together.
Prince Charming tries to rebuild his marriage, but he can't ignore his feelings for Snow White. This woman whom he (falsely) thinks is his wife brings out no current feelings, but he seems to have memories of feelings for her, and he tries to make it work. Technically, he's living in an adulterous relationship with her while thinking his feelings for Snow White are the adulterous ones. But Snow White is really his wife, and some process within him is leading him to think he should be with her. But he has no access to what would be leading him to that. An externalist would say that he has some process within him that he can't understand that's leading him to know that Snow White is the one for him, and his false beliefs about his past do not interfere with that knowledge. An internalist has to say that his most justified beliefs are the false ones.
So suppose there's some reliable process whereby his body's memories of his love for Snow White are leading him to know that she's really the one he's supposed to be with. His resistance to this woman who isn't his wife, whom he believes is his wife, is then grounded in processes that he has no access to. An externalist could say that his belief that he should be with Snow White (whom he knows now by another name, of course) is justified by these processes he's unaware of, and it's bogus to rely on his memories for the belief that he's married to the other woman. An internalist would say that his belief that he is married to the other woman is in fact false but is justified. Which belief is justified, then, depends on which epistemology is correct.
Which view you adopt would seem to have significant moral implications. He's doing something clearly wrong, according to internalism, by having clandestine romantic interactions with Snow White. But what if he has knowledge on some level that can somehow cancel his seeming knowledge (that isn't knowledge at all) that this is adultery? Those are false beliefs, based on false memories. If he doesn't know those things but falsely believes them, and he also knows on some level that Snow White is his true love, is it enough to remove the wrongness of the adultery? Perhaps that's too much, but it does seem to be ethically different in some ways.