There are two questions to ask about Peter Singer, who in sheer practical impact (as founder of the contemporary animal-liberation movement) is the most important philosopher alive. Are his views on ethical matters like infanticide and euthanasia right or wrong? If the latter, are they so outrageously and despicably wrong that he should be kept out of the Princeton chair in ethics or otherwise silenced?
The Wall Street Journal, the New York Observer, and angry editorialists in other publications have not bothered to reason about the first question. They have simply caricatured Singer's views (save the cows, kill the disabled babies), linked him to the sinister left, called him names like "Professor of Death," and deplored the fact that gullible Princeton undergrads would be mindlessly imbibing his propositions next year. (My favor slur against Singer, repeated by the Wall Street Journal among others, is that "three German parliamentarians have likened him to Hitler deputy Martin Bormann.")
You, Professor McGinn, have at least taken Singer's reasoning seriously by attempting to show where it goes awry on the way to a conclusion you disagree with: the permissibility of infanticide. But you also accuse Singer of "bad judgment" in accepting this "morally absurd" and "repugnant" conclusion himself. (Bad enough judgment to have his chair in ethics at Princeton withdrawn?) If Singer were a responsible philosopher, he would have concluded instead that his logic must have been faulty.
A moral theory, like any other theory, should "save the appearances." Infanticide certainly appears to be repugnant--to post-Judeo-Christian intellectuals like ourselves, at least. Of course, some of our settled convictions, on matters like abortion, are deemed equally repugnant by thinkers of a more orthodox religious cast. And there have been plenty of perfectly respectable non-Christian cultures where selective infanticide was considered not only permissible, but morally mandatory. Plato, Aristotle, and Seneca all advocated the killing of deformed neonates, and Solon put the principle in his legislative code.
Whether it is we or the ancients who have the moral tin ear is irrelevant to the logic of Singer's argument--and to your counter-argument, which I'll put off considering until the next installment. But first: Did you realize that infanticide is going on all the time in hospitals today? When a baby is born with spina bifida--a malformation of the spine that typically leads to a life of paralysis, incontinence, and severe retardation--doctors often withhold, with the parents' consent, the treatment necessary for it to survive. Infants born with aggravated Down syndrome are allowed to expire without getting the operation they need to keep their heart intact. You might argue that this is "passive euthanasia" rather than infanticide, but do you really think there is an important moral distinction between acting and omitting to act in these situations?
Like any sane person, Singer opposes the killing of healthy newborns, just as he opposes late-term abortions. In both cases, a sentient being who is likely to have (on balance) a happy life is destroyed. The wrongness of doing this follows straightforwardly from Singer's ethical theory, utilitarianism. But if a newborn has some condition that would make its future life as a person sheer misery, he thinks that it is morally acceptable for the parents to have it (painlessly) killed in the first month after birth--especially if they are planning to have another child in its place. Nowadays, as it happens, this is rarely necessary. Most genetic deformities can be diagnosed prenatally, and the parent can opt for a "eugenic" abortion and start over. (They might choose to do this even if the condition is something non-misery-threatening but merely inconvenient, like hemophilia--abortion is, after all, legally a private decision.)
In some cases, however, the disabling damage happens during the birth process, and that is when Singer would like infanticide to be an option for the parents. The temptation to neonatal euthanasia will become rarer and rarer with improvements in birth technology. And even eugenic abortion will become a thing of the past when "germ-line" intervention in a child's DNA will allow parents the option of correcting all sorts of genetic flaws. Thus can science pop what is now a burning issue of practical ethics into the oubliette of history.
But I do want to consider your counter-argument to Singer. To have a right to life, it is not enough to be a potential person--a three-month fetus is that. It is not enough to be sentient--a laboratory rat is that. One must be both. How do these two statuses blend into one in your moral logic?
P.S. When my friends talk about "infanticide," they usually mean drinking vintage port before it is mature.