Ethics and Evolution

When Charles DARWIN wrote The Origin of Species, he withheld discussion of the origins of human morality and cognition. Despite Darwin's restraint, some of the strongest reactions to the theory of natural selection had to do with its connection to ethical matters. The intersection between evolution and ethics continues to be a site of controversy. Some claim that human ethical judgments are to be explained by their adaptive value. Others claim that human ethical systems are the result of cultural evolution, not biological evolution. In the context of cognitive science, the central issue is whether humans have ethics-specific beliefs or cognitive mechanisms that are the result of biological evolution. There is increasing evidence that the human brain comes prewired for a wide range of specialized capacities (see NATIVISM and DOMAIN SPECIFICITY). With regard to ethics, the central questions are to what extent the human brain is prewired for ethical thinking and, insofar as it is, what the implications of this are.

There is one sense in which humans are prewired for ethics: humans have the capacity for ethical reasoning and reflection while amoebas do not. This human capacity is biologically based and results from EVOLUTION. Ethical nativism is the view that there are specific, prewired mechanisms for ethical thought. Adherents of SOCIOBIOLOGY, the view that evolutionary theory can explain all human social behavior, are among those who embrace ethical nativism. E. O. Wilson, in Sociobiology: The New Synthesis (1975), goes so far as to say that ethics can be "biologized." Sociobiologists claim that humans have specific ethical beliefs and an associated ethical framework that are innate and are the result of natural selection. They support this view with evidence that humans in all cultures share certain ethical beliefs and certain underlying ethical principles (see HUMAN UNIVERSALS), evidence of ethical or "pre-ethical" behavior among other mammals, especially primates (see de Waal 1996), and with evolutionary accounts of the selective advantage of having innate ethical mental mechanisms. Most notably, they talk about the selective advantage (to the individual or to the species) of ALTRUISM.

Consider a particular moral belief or feeling for which an evolutionary explanation has been offered, namely the belief that it is wrong to have (consensual) sex with one's sibling. Some sociobiologists have argued that this belief (more precisely, the feeling that there is something wrong about having sex with a person one was raised with) is innate and that we have this belief because of its selective advantage. When close blood relatives reproduce, there is a relatively high chance that traits carried on recessive genes (most notably, serious diseases like sickle-cell anemia and hemophilia) will be exhibited in the resulting offspring. Such offspring are thus more likely to fail to reproduce. Engaging in incest is thus an evolutionarily nonadaptive strategy. If a mutation occurred that caused an organism to feel or believe that it is wrong to engage in incest, then, all else being equal, this gene would spread through the population over subsequent generations. Sociobiologists think they can give similar accounts of our other ethical beliefs and the mechanisms that underlie them.

What are the implications for ethics if ethical nativism and some version of the sociobiological story behind it are true? Some philosophers have denied there are any interesting implications. Ethics, they note, is normative (it says what we ought to do), whereas biology -- in particular, the details of the evolutionary origins of humans and our various capacities -- is descriptive. One cannot derive normative conclusions from empirical premises. To do so is to commit the naturalistic fallacy. It would be a mistake, for example, to infer from the empirical premise that our teeth evolved for tearing flesh to the normative conclusions that we ought to eat meat. This empirical premise is compatible with ethical arguments that it is morally wrong to eat meat. By the same reasoning, the fact that evolution produced in us the tendency to have some moral feeling or belief does not necessarily entail that we ought to act on that feeling or accept that belief on reflection. In fact, some commentators have suggested, following Thomas Huxley (1894), that "the ethical progress of society depends, not on imitating [biological evolution], . . . but in combating it."

Ethical nativists have various responses to the charge that they commit the naturalistic fallacy. Some allow that the fact that humans have some innate moral belief does not entail that we ought to act on it, while insisting that nativism has something to tell us about ethics. Perhaps biology can tell us that we are not able to do certain things and thus that it cannot be the case that we ought to do this. For example, concerning feminism, some sociobiologists have claimed that many of the differences between men and women are biologically based and unchangeable; a feminist political agenda that strives for equality is therefore destined to failure. This argument has been criticized on both empirical and normative grounds (see Kitcher 1985 and Fausto- Sterling 1992).

Some sociobiologists (Wilson 1975 and Ruse 1986) have argued that the facts of human evolution have implications for moral realism, the metaethical position that there are moral facts like, for example, the moral fact that it is wrong to torture babies for fun. A standard argument for moral realism says that the existence of moral facts explains the fact that we have moral beliefs (on moral realism, see Harman 1977; Mackie 1977; Brink 1989). If, however, ethical nativism is true and an evolutionary account can be given for why people have the moral beliefs they do, then an empirical explanation can be given for why we have the ethical capacities that we do. The standard argument for moral realism is thus undercut.

One promising reply to this line of thought is to note that moral facts might be involved in giving a biological account of why we humans have the moral beliefs that we do. In the case of incest, the moral status of incest might be related to the selective advantageousness of incest. Consider an analogy to mathematics. Although we might give an evolutionary explanation of the spread of mathematical abilities in humans (say, because the ability to perform addition was useful for hunting), mathematical facts, like 2 + 2 = 4, would still be required to explain why mathematical ability is selectively advantageous. Many of our mathematical beliefs are adaptive because they are true. The idea is to give the same sort of account for moral beliefs: they are selectively advantageous because they are true. Selective advantage and moral status can, however, come apart in some instances. One can imagine a context in which it would be selectively advantageous for men to rape women. In such a context, it might be selectively advantageous to have the belief that rape is morally permissible. Rape would, however, remain morally reprehensible and repugnant even if it were selectively advantageous to believe otherwise.

Even if there is a tension between ethical nativism and moral realism, the tension might not be so serious if only a few of our ethical beliefs are in fact innate. Many of our ethical beliefs come from and are justified by a reflective process that involves feedback among our various ethical beliefs; this suggests that many of them are not innate. The nativist argument against moral realism depends on the strength of its empirical premises.

See also

Additional links

-- Edward Stein


Brink, D. O. (1989). Moral Realism and the Foundations of Ethics. Cambridge: Cambridge University Press.

de Waal, F. (1996). Good Natured: The Origins of Right and Wrong in Humans and Other Animals. Cambridge: Harvard University Press.

Fausto-Sterling, A. (1992). Myths of Gender: Biological Theories about Women and Men. Rev. ed. New York: Basic Books.

Harman, G. (1977). The Nature of Morality. Oxford: Oxford University Press.

Huxley, T. H. (1894). Evolution and Ethics and Other Essays. New York: D. Appleton.

Kitcher, P. (1985). Vaulting Ambition. Cambridge, MA: MIT Press.

Mackie, J. L. (1977). Ethics: Inventing Right and Wrong. New York: Penguin.

Ruse, M. (1986). Taking Darwin Seriously. Oxford: Blackwell.

Wilson, E. O. (1975). Sociobiology: The New Synthesis. Cambridge, MA: Harvard University Press.

Further Readings

Bradie, M. (1994). The Secret Chain: Evolution and Ethics. Albany: SUNY Press.

Goldman, A. (1993). Ethics and cognitive science. Ethics 103:337-360.

Lumsden, C., and E. O. Wilson. (1981). Genes, Minds and Culture. Cambridge, MA: Harvard University Press.

Nitecki, M., and D. Nitecki, Eds. (1993). Evolutionary Ethics. Albany: SUNY Press.

Nozick, R. (1981). Philosophical Explanations. Cambridge, MA: Harvard University Press.

Thompson, P., Ed. (1995). Issues in Evolutionary Ethics. Albany: SUNY Press .