"Respect for the sanctity of human life is the underlying value of the medical ethic." So said Professor Carl E. Taylor1 in a recent paper, placing the whole medical enterprise—its science and its practice—into its larger framework in the value structure of human society. It is within this framework that one should consider the ethics of the use of animals in all biological and especially medical investigation and teaching.
Philosophers have argued throughout human history about the logical basis of ethics. In our own times it has been conceded that the morality of an act must be judged in the light of the total context in which it is performed. Furthermore, philosophers have all but abandoned hope of defining from a priori principles the essence of good or bad. As Professor A. J. Ayer2 has put it recently, "We find that argument is possible on moral questions only
Maurice B. Visscher. Medical Research and Ethics. JAMA. 1967;199(9):631–636. doi:10.1001/jama.1967.03120090073013