The mainly social nature of humanity's existence has necessitated an apparatus of ideas for evaluating, amongst other things, the acceptability of personal interactions. The idea of consent is an important part of this apparatus. We find it a valuable ingredient in our thinking about such activities as physical, sexual, or psychic invasion, and the transfer or use of property. We commonly say that if someone performs one of these activities without the consent of another person whom we identify as having rights in the matter, they do a wrong; and, albeit perhaps a little less commonly, that if the other person does consent, they do not do a wrong. And we go on to articulate at least some of this thinking in the form of rules of the criminal law.