Now where is the Darwinian explanation for Kolbe’s sacrifice? It does not exist. Ernst Mayr, a leading evolutionary biologist, admits that “altruism toward strangers is a behavior not supported by natural selection.” I have great respect for the work of Fisher, Trivers, and others in their field, and I do think that in time the evolutionists will produce more satisfactory accounts of human cultural and moral behavior. But I predict their project to comprehensively account for morality in Darwinian terms will fail. The Darwinian project is necessarily confined to the domain of self-interest, and it is the essence of morality to operate against self-interest. The whole point of morality is that you are doing what you ought to do, not what you are inclined to do or what is in your interest to do. Morality is described in the language of duty, and duty is something that we are obliged to do whether we want to or not, whether it benefits us or not.

C. S. Lewis demonstrates this point with a beautiful example that I am modifying for my own purpose. You are walking on the river bank, and you hear the screams of someone who is drowning. You are a very poor swimmer and the fellow is nothing to you. If two of your brothers were drowning you might jump in, because each of them has half your genes. If a bunch of your relatives were in a boat that was sinking you might jump in, because this might be a reasonable strategy for your genes to live on through your aunts, uncles, and cousins. In this case, however, the drowning man is unrelated to you. Kin selec- tion is not involved, and neither is reciprocal altruism, as there is no reason to think that there will be an occasion when he will risk his life to save yours. And yet, Lewis points out, there is a little voice in your head that says you should jump into the water and try to save the man’s life. Darwinian thinkers like Dawkins realize that this cannot be explained as “acting for the good of society” because why should self-interested people care what’s good for society except when it benefits them? For you to worry about the good of society, youhave to be unselfish in the first place, and this is what we are trying to explain.

A better answer is that human beings have a “herd instinct” or an instinctive natural sympathy for members of our own species, and perhaps this can account for rival inclinations: one saying “go ahead and help,” the other saying “leave and don’t help.” Lewis notes that even when there are competing inclinations like this, a third voice, distinct from the other two, enters the picture. This is the voice that says you ought to help. Speaking gently but with unmistakable firmness, the voice urges you to listen to the good inclination that says “help” and ignore the selfish inclination that says “don’t help.” That is the hidden call of conscience.