Perhaps there is no concept which needs a more thorough revision than that of social and legal responsibility. According to the old theory, accepted alike in psychology and in law, human beings could be divided into two absolutely distinct classes, the sane and the insane, the one completely rational and completely responsible, and the other completely irrational and completely irresponsible. It followed, then, that society could protect itself perfectly against any antisocial acts on the part of the first class by attaching to such transgressions penalties sufficient to outweigh the advantages derived therefrom; and it followed just as logically that such penalties were of no avail against the second class.
Unfortunately for the theory, human nature persists in escaping from rigid categories. On the one hand, we find that many of the mentally subnormal are capable of responding rationally, in greater or less degree, to incentives supplied by rewards and