  There are two reasons to answer the first question in the affirmative. One invokes (C). If courts are to develop criminal defences so that their contours track culpability, they need to know why each defence makes it the case that those who plead it are not culpable. Is there a defence of necessity because we sometimes do the right thing by choosing the lesser of two evils? Or does the defence exist because actors sometimes make wrongful choices under enormous pressure, and because there is sometimes nothing culpable about giving into the pressure? How courts should develop the defence depends on how they answer these questions. It depends on whether they conceive of the defence as a justification or an excuse.