In medicine, in biology, in the social sciences, in pharmacology– many recent advances in these fields have been accomplished largely by experimentation with human beings. In some of these instances, it is claimed, no progress could have been made without such experiments. Yet most of us recoil from such a notion. The biblical idea of the sanctity of life, the Kantian injunction that persons should be treated as ends not means, our horror at the experiments conducted by Nazi doctors all make us shrink from approval of these efforts.