When does self-interest distort moral belief?

In this paper, I critically analyze the notion that self-interest distorts moral belief-formation. This belief is widely shared among modern moral epistemologists, and in this paper, I seek to undermine this near consensus. I then offer a principle which can help us to sort cases in which self-interest distorts moral belief from cases in which it does not. As it turns out, we cannot determine whether such distortion has occurred from the armchair; rather, we must inquire into mechanisms of social power and advantage before declaring that some moral position is distorted by self-interest.