Many people think that evolution undermines objective ethics. How can we say that ethical judgments are true or false, if these judgments arise from evolution by natural selection? Evolution is concerned only with what enhances reproductive success. To the extent that genes that lead to certain behavior give a selective advantage to their carriers, they will tend to spread through the population. If this explains why we act, this appears to leave no room for explaining ethical behavior though its conformity to truth.
One way people who believe in objective ethics can respond to this line of thought is to question whether evolution suffices to account for morality. Thomas Nagel is probably the most famous philosopher who argues to this effect, and he goes further. In his view, many philosophers have an irrational commitment to evolution by natural selection. (See his Mind and Cosmos [Oxford University Press, 2012]). I agree with Nagel, but Robert Nozick most certainly did not. It would be difficult to find a thinker more devoted to evolution than Nozick, but he did not give up ethical objectivity.
In what follows, I’d like to examine what he has to say on the topic in his masterpiece, Philosophical Explanations (Harvard University Press, 1981). The book is filled with an amazing number of interesting points, but its labyrinthine style displeases some philosophers who prefer a deductive system and scorn what fails to conform to their requirements. The book has meant a great deal to me since I first read it in manuscript before publication, and I spent several sleepless nights devouring it.
In the book, Nozick suggests that objective ethics can survive the evolutionary challenge. He draws a parallel with the ability to recognize mathematical truths:
If ethical behavior is adaptive, if that behavior increases inclusive fitness, and is genetically based and heritable, over the generations it will spread more and more widely. Ethically behaving individuals will leave more great great-grandchildren or (given kin selection) great-grandnephews and nieces similarly disposed. However, the explanation of the spread of ethical behavior. . .does not undercut the (possible) role of ethical facts in the origin of that behavior, or in the performance of later generations. To see this point, suppose that a knowledge of rudimentary truths of number theory has adaptive value, because of the advantages it gives in warfare, the hunt, domestic activity, or whatever. If the capacity to recognize such truths and the predisposition to act on them is genetically based and heritable, these capacities will spread in the population so that a higher proportion of these organisms will come to take account of arithmetical truths in their behavior. But though the spread is explained “blindly”, each individual’s behavior is not. The first individuals recognized that 2+2 = 4 and similar such facts; to explain their behavior, and its success, we have to introduce the fact that their arithmetical statements are true. Because of the advantage bestowed, these individuals left more descendants with similar arithmetical capacities. Their behavior too is to be explained in terms of their recognition of arithmetical truths.
Nozick next brings in ethics. Why can’t what holds in mathematics also hold in ethics?
If ethical behavior increases inclusive fitness, this will explain the spread of such behavior in the population. Yet each individual’s behavior, ancestor or descendant, might be explained by her recognizing certain ethical truths and acting on them. . . It is compatible with an evolutionary explanation that it is a capacity to detect or to track some truths.
Might be; but that does not show that it is the case. Maybe people’s ethical behavior can be explained by their beliefs about ethics, without requiring that the beliefs be true. Nozick first suggests that the explanation of their ethical behavior without reference to the truth of the beliefs would be incomplete:
Must truth be brought in? Cannot we explain beliefs in terms of the explicitly nonevaluative facts that underlie the moral truths, those in virtue of which the (supervenient) moral truths hold, without bringing the truth of the moral beliefs into the explanation? But then why the people come to have that moral belief under that factual situation would be left without explanation, as a brute fact.
Nozick now goes on the attack. It’s very likely that the beliefs people have will be ones that are true:
Will the explanation of why the ethical beliefs are selected for, or why the behavior is adaptive, bring in the fact that these beliefs are true? However the behavior increases inclusive fitness, won’t the connection be independent of the truth of the beliefs? The ethical behavior will serve inclusive fitness through serving or not harming others, through helping one’s children and relatives, through acts that aid them in escaping predators, and so forth; that this behavior is helpful and not harmful is not unconnected to why (on most theorist’s views) it is ethical. The ethical behavior will increase inclusive fitness through the very aspects that make it ethical, not as a side effect through features that only accidentally are connected with ethicality.
You might object to this that the truths that Nozick mentions aren’t the whole of ethics. What about the rest? Nozick answers that the case is similar to the truths of arithmetic. Once you have some of them, new possibilities will lie open to discovery:
The explanation of the adaptedness of arithmetical capacities probably will not bring in the truth of the arithmetical beliefs much more than this [i.e., more than elementary truths]. . . And in each case, arithmetical and ethical, the capacities of recognition selected for will reveal splendors beyond the useful. . . The capacity to recognize ethical truths unveils surprising structures, convolutions, refinements, modulations, and asymmetries.
I hope this gives you some idea of what Philosophical Explanations is like, though I have left out the technical details and complications. Now imagine yourself going through 750 pages of this!
