Moral Philosophy as Applied Science

Ruse and Wilson in “Moral Philosophy as Applied Science” give the example of brother-sister incest avoidance as being an ethical code motivated by an epigenetic rule that confers an adaptive advantage on those who avoid intercourse with their siblings. In this discussion, Ruse and Wilson argue that moral laws disallowing incest are redundant relics of mankind’s evolutionary history that provide nothing to mankind but explanations of a hard-wired evolutionary trait (179). I reject this argument. While Ruse and Wilson are undoubtedly correct in believing that mankind’s capacity for moral reasoning is a result of natural selection pressure and that most ancient moral laws have an evolutionary basis, I believe that describing the genesis of moral reasoning in this way provides no information about the content of our moral beliefs now. While our capacity for moral reasoning may have evolved for the purpose of informing our otherwise unjustifiable acts with a sense of objective certitude, it is not hard to imagine that this capacity, once evolved, would be capable of much more than simply rubber stamping mankind’s collective genetic predisposition. In this paper, I will use the example of an evolutionary explanation against intentional killing for personal gain to argue for the existence of a disconnect between evolutionary biology and ethics.

Ruse and Wilson might argue that human beings evolved with a genetic predisposition against murder for convenience. It is easy to see how this might be true. A person who kills others for convenience must live apart from society and apart from potential mates or else must be killed by society. This epigenetic rule “predisposes us to think that certain courses of action are right and certain courses of action are wrong (180).” These motivate ethical premises which “are the peculiar products of genetic history” and can “be understood solely as mechanisms that are adaptive for the species that possess them (186).”

I reject this notion that evolution completely prescribes ethics. Nature is amoral absent intelligent beings who make moral judgements. Once the capacity for moral reasoning is established, it does not follow that our ethical laws must necessarily mimic our evolutionary predisposition. While in the cases of selection against brother-sister incest avoidance or against murder for convenience it is easy to see how evolution can bring about an outcome that we now judge to be moral, it can just as easily effect traits that we now believe immoral. Few people would believe that man’s evolutionary desire to replicate his genetic material in children would ethically justify licentiousness. Few would believe that women should be dominated by men simply because in nature males tend to be stronger and dominant. Discovering a scientific explanation for man’s dominance of women in human history would not justify humanity reverting to sexism. This is a simple counterexample suggesting that discovering a scientific basis for a trait does not a priori suggest the desirability of its expression in society.

The authors do not free themselves from the naturalistic fallacy of the is-ought distinction. We may consider their argument as follows:

1. Humans tend not to murder for convenience because a naturally selected genetic trait tends to make people not murder for convenience.

2. Humans have good reason not to commit murder.

This argument seems strong. Our genetics cause us not to murder for convenience; we later conceive of an ethical code to rationalize this evolutionary preference in terms of objective truth. However, we still need an ought statement to justify statement two. In particular we need:

3. Humans have a good reason to follow their epigenetic tendencies .

Ruse and Wilson have not freed themselves from the naturalistic fallacy. They instead have a suppressed normative premise: that humans should follow their genetic predispositions. They in fact supppose an evolutionary ethics, that the proper course of action is the one we are genetically predisposed to follow. They claim that “the quest for scientific understanding replaces the hajj and the holy grail.” They have conceived of a new ethics that will supersede mankind’s misplaced faith in “imagined rulers in the realms of the supernatural and eternal (86).” The new ethics is based on the simple premise that we should act according to our evolutionary nature.

This may or may not be a useful system of ethics. It will certainly lead to some outcomes, like sexism, that would seem to contradict the advice of other