Argument about vivisection has often missed the point because it has been put in absolutist terms: would the abolitionist be prepared to let thousands die if they could be saved by experimenting on a single animal? The way to reply to this purely hypothetical question is to pose another: Would the experimenter be prepared to experiment on a human orphan under six months old, if it were the only way to save many lives? (I say "orphan" to avoid the complication of parental feelings, although in doing so I am being overfair to the experimenter, since the nonhuman subjects of experiments are not orphans.) A negative answer to this question indicates that the experimenter's readiness to use nonhumans is simple discrimination, for adult apes, cats, mice, and other mammals are more conscious of what is happening to them, more self-directing, and, so far as we can tell, just as sensitive to pain as a human infant. There is no characteristic that human infants possess that adult mammals do not have to the same or a higher degree.
(It might be possible to hold that what makes it wrong to experiment on a human infant is that the infant will in time develop into more than the nonhuman, but one would then, to be consistent, have to oppose abortion, and perhaps contraception, too, for the fetus and the egg and sperm have the same potential as the infant. Moreover, one would still have no reason for experimenting on a nonhuman rather than a human with brain damage severe enough to make it impossible for him to rise above infant level.)
The experimenter, then, shows a bias for his own species whenever he carries out an experiment on a nonhuman for a purpose that he would not think justified him in using a human being at an equal or lower level of sentience, awareness, ability to be self-directing, etc. No one familiar with the kind of results yielded by these experiments can have the slightest doubt that if this bias were eliminated the number of experiments performed would be zero or very close to it.
(Peter Singer, "Animal Liberation," review of Animals, Men and Morals, ed. by Stanley Godlovitch, Roslind Godlovitch, and John Harris, The New York Review of Books 20 [5 April 1973]: 17-20)
Note from KBJ: Singer was 26 years old when this review was published. It is his first publication (of many) on the moral status of nonhuman animals.
