 (iv) Finally, the distinction between doing and allowing harm is sometimes thought to have, as part of its conceptual content, a moral element. This thought is rarely made explicit, but the way people are inclined to classify cases suggests that they are guided by it. There are two main difficulties with this way of drawing the line. Firstly, if it is true by definition that killing is worse than letting die, then the question of whether killing is worse than letting die is settled in a trivial, circular, uninteresting way. Secondly, there are obvious counterexamples to this crude account—morally appalling cases of letting die—failing to feed one’s children—and morally acceptable cases of killing. We have no hesitation talking of killing in self-defense.