If Absolute Idealism is true, the harm one inflicts on another may metaphysically affect oneself or a larger mind-like whole, but this effect is never experienced by the person confined to the world of Appearance.
Now this argument has an interesting corollary which Russell does not explicitly draw. It may be that in Reality the pains I inflict on you affect me—or at least a larger mind-like thing in which we both participate—but if I never experience those effects, how can this give me a motive to do or forbear if my interests conflict with yours? How can the fact that you and I are in Reality one (or at least part of one) give me a reason to look out for you, if this oneness is something I never experie