Consider two cases. In both cases, we have two hypotheses that explain data. For simplicity think of the data as data of sense. In one case, the hypotheses are a common sense one and a skeptical hypothesis. In the other, the hypotheses are two rival scientific explanations.
If you’re inclined toward common sense epistemology, you’ll be inclined to think that in the first case, the common sense hypothesis is justified (or made rational) by the data; and if you’ve got any understanding of how science works, you’ll hold that the data don’t confirm either theory in the second case. So, what’s the difference?
Peter Markie and I were talking about this question the other day, and he’s inclined to answer as follows. In the first case, the data prima facie justify the common sense view, and in the second case, the data do not justify either. The reason we find the two cases puzzling is that we are inclined to think there is a connection between justification and explanation, and though there may be, there isn’t enough of a connection to read off the justificatory facts from the explanatory ones.
Is this a good answer?