ABSTRACT
Some, most clearly Sarah McGrath, have argued that the amount of peer disagreement that we face about controversial moral topics undermines the possibility of moral knowledge and justified moral belief in a way that the amount of peer disagreement that we face about non-moral topics does not undermine the possibility of knowledge of, and justified belief about, non-moral topics. Call this argument the argument for moral skepticism from peer disagreement. Jason Decker and Daniel Groll have recently made a companions in guilt argument against this argument. Decker and Groll argue that if peer disagreement undermines moral knowledge and justified moral belief in the way that McGrath, for instance, claims that it does, then peer disagreement undermines much non-moral knowledge and non-moral justified belief; if the argument for moral skepticism from peer disagreement succeeds, then a kind of non-moral skepticism holds too. And we should not, and McGrath does not, hold that such non-moral knowledge and non-moral justified belief is undermined by peer disagreement. In this paper, I shows that Decker and Groll’s companions in guilt argument fails. I then discuss whether peer disagreement about moral topics undermines all moral knowledge and justified belief. I argue that peer disagreement about morality does not undermine all moral knowledge and justified belief but that peer disagreement about morality does preclude most moral beliefs from being justified and constituting knowledge in a way that peer disagreement about non-moral topics does not preclude most non-moral beliefs from being justified and constituting knowledge.
