Dear Professor Singer:
I am not a moral skeptic in the sense of believing that moral beliefs have no effect on human behavior. I am merely skeptical that such beliefs can be changed by philosophical arguments (especially those of academic philosophers, given the sheltered character of the modern academic career in the United States and other wealthy liberal countries), as distinct from being changed by experience, by changes in material circumstances, by the demonstrated success or failure of particular moral principles as means of coping with the problems of life, and by personal example, charismatic authority, and appeals to emotion. In yesterday's exchange I gave examples of how moral principles, for example regarding sex, are changed by such things, and I questioned whether academic philosophy had played any significant role in the changes I discussed.
Although you are correct that the efficacy and the soundness of moral arguments are analytically distinct issues, they are related. One reason moral arguments are ineffective in changing behavior is their lack of cogency—their radical inconclusiveness—in a morally diverse society such as ours, where people can and do argue from incompatible premises. But there is something deeper. Moral argument often appears plausible when it is not well reasoned or logically complete, but it is almost always implausible when it is logical. An illogical utilitarian (a "soft" utilitarian, we might call him or her) is content to say that pain is bad, that animals experience pain, so that, other things being equal, we should try to alleviate animal suffering if we can do so at a modest cost. You, a powerfully logical utilitarian, a "hard" utilitarian, are not content with such pablum. You want to pursue to its logical extreme the proposition that pain is a bad by whomever experienced. And so you don't flinch from the logical implication of your philosophy that if a stuck pig experiences more pain than a stuck human, the pig has the superior claim to our solicitude; or that a chimpanzee is entitled to more consideration than a profoundly retarded human being.
You challenge my example of the 101 chimpanzees. Invoking the positive side of utility (pain is the negative side), you argue that "the ability to see oneself as existing over time, with a past and a future, is an important part of what makes killing some beings more seriously wrong than killing others." It's telling that you say "beings" rather than "human beings." There is scientific evidence that nonhuman primates have some "ability to see [themselves] as existing over time, with a past and a future," and I meant by my example to suggest that this ability might be as much as 1 percent of the ability of the average human being. And then it follows from the logic of your position that it is indeed worse to kill 101 of these primates than to kill a single normal human being, let alone a single retarded human being whose ability to see himself as existing over time, with a past and a future, may be little superior to that of the average chimpanzee. This tough-minded, indeed hard-boiled, conclusion is implied by your statement that "we do wrong when we give animals less consideration, simply because they are not human" (my emphasis).
The "soft" utilitarian position on animal rights is a moral intuition of many, probably most, Americans. We realize that animals feel pain, and we think that to inflict pain without a reason is bad. Nothing of practical value is added by dressing up this intuition in the language of philosophy; much is lost when the intuition is made a stage in a logical argument. When kindness toward animals is levered into a duty of weighting the pains of animals and of people equally, bizarre vistas of social engineering are opened up. You say there would be "something odd about a democratic government prohibiting the eating of meat if the majority of its citizens were strongly and consistently in favor of meat-eating," but you don't say it would be wrong to force vegetarianism on the majority (not all democratic legislation is majoritarian). Nor do you indicate any reservations at all about legislation that would force vegetarianism on a minority of the population that was strongly and consistently in favor of meat-eating. If 49 percent of the population very much wanted to eat meat, would you think it right to forbid them to do so, merely because they were a minority in a democratic system? I infer that you would; and it is an example of why I think we would be better off without philosophical arguments for moral and political change.
You suggest that a vow of abstinence from philosophical argument would disempower us to condemn racism and homophobia. Not so. The causes and consequences of bigotry have a long, well-studied history, rich with lessons that do not require philosophical spin to convince. It is the lessons of history, and not the thought of Plato or Aristotle or Kant or Heidegger, that caused most philosophers, along with nonphilosophers, eventually to turn against racism and homophobia. Philosophy follows moral change; it does not cause it, or even lead it.
Thrasymachus in Plato's Republic, with whom you compare me, taught that might makes right; Socrates, in the Republic, while rejecting Thrasymachus' definition of justice, advocated censorship, the destruction of the family, and totalitarian rule by—philosophers. So moral philosophy has its hard side (consider also Aristotle's defense of slavery, and Kant's of capital punishment) and in our debate, Professor Singer, it is you who are the tough guy, and I the softie, the sentimentalist, willing to base animal rights on empathy, unwilling to follow the utilitarian logic to the harsh conclusions sketched above.
But it would be wrong to end on so negative a note. I wish to end by recording my high personal and professional regard for you. I admire the clarity of your thought and your intellectual courage in pursuing the logic of your philosophy all the way—to its unacceptable conclusions.
Richard A. Posner