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Review of Darwinian Natural Right: The Biological Ethics of Human Nature by Larry Arnhart


Review: Darwinian Natural Right: The Biological Ethics of Human Nature, by Larry Arnhart. State University Press of New York (1998). ISBN 0-7914-3693-4; paperback ISBN 0-7914-3694-2.

It has become something of a leitmotif among evangelical apologetes to argue that morality can have no objective foundation if there is no God. Using a strategy that appeals to many people’s strong intuitions that there are objective rights and wrongs, they claim seek to convict atheists of being intellectually committed to moral relativism, subjectivism, or nihilism. Those are, of course, ethical positions that have been advocated by some atheists. But others share the intuition that there are objective moral norms, and also that we can, on the whole, come to know what they are.

Larry Arnhart’s Darwinian Natural Right is an able defense of one moral theory that makes no appeal to the supernatural. Arnhart’s position stands in a venerable tradition of what are sometimes called naturalistic theories of ethics or ethical naturalism, theories that consider moral rights and wrongs, goods and evils, to derive from or supervene upon certain natural facts about persons. Ethical naturalism can trace its history back at least to Aristotle. It also has conceptual ties with Medieval natural-law theories, though according to these, the natural laws from which moral norms derive are built into (our human) nature by God, and hence derive ultimately from Him. Somewhat later, during the early modern period, Arnhart sees David Hume as an important nontheistic defender of ethical naturalism.

Ethical naturalism is, of course, not the only sort of nontheistic conception of objective ethical truths. There are, e.g., egoist, utilitarian, and deontological theories which accord objective status to morality. Christian apologetes all too often overlook or simply ignore these nontheistic competitors—not to mention paying too little attention to the metaphysical and epistemological difficulties that beset Divine Command theories of ethics and their close cousins.

In brief, Arnhart’s argument is that human beings (the only full-fledged persons we know to exist) have evolved by means of Darwinian processes into creatures who use reason and communication in the service of satisfying their natural desires. These “natural” desires are ones that are universal for our species, and they are desires for things that contribute to our flourishing. In particular, because of our fundamental sociality—itself a basic adaptation rooted in the need for durable family structures that can devote sufficient resources to the raising of children—we have desires the pursuit of which gives rise to moral constraints upon action. In short, human beings occupy an adaptive niche in which strong social bonds and intelligent cooperative planning are necessary for the successful rearing of children (among other things), because a heavy investment in child-rearing—heavier than for any other species—is biologically required for the maturation of our large brains.

Arnhart lists some twenty desires that are humanly universal. He discusses in some detail parental care, sexual identity and mating, familial bonding, social ranking, justice as reciprocity, political rule, war, and religious and intellectual understanding. His strategy throughout is to show how the social rules and arrangements required to fulfill these desires generate the basic moral norms that are universal and proper to human beings. He argues that other social animals—social insects, for example—lack moral norms because they lack human reason and foresight. Yet even in the social insects, and in a much more sophisticated way in the social apes, certain behaviors (for example, altruistic ones) are naturally selected and form the evolutionary prototypes of our moral convictions. By contrast, a few human beings—psychopaths—lack moral sensibilities because they lack the normal complement of human desires. Their existence, Arnhart claims, can also be explained in Darwinian terms. They are “free-riders” who can succeed by preying upon others when most of those others are honest cooperators.

As I see it, Arnhart is on very much the right track. There are, at the same time, a number of conceptual unclarities and moral intuitions that suggest ways in which his account might be improved and extended. Here I shall mention some of these, without in any way being able to do them justice.

First, Arnhart sees moral norms as deriving from (contingent) human desires, in particular from certain basic desires that are humanly universal, or at least ‘normal.’ He does not distinguish, unfortunately, between felt desires (such as hunger) and what might be called desiderata (the term needs is more common, but many things that one should strive for are not strictly necessary, though they promote human flourishing). The desiderata include things for which we feel desire, but we do not feel desire for every desideratum. Thus desiderata can be specified for organisms that altogether lack feeling—e.g., adequate water and sunshine for a plant. And many of us may feel desire for what is not (all things considered) a desideratum and is harmful. As Arnhart begins to make clear in his Chapter 9, “The Ends and Kinds of Life,” it is the desiderata, rather than felt desires as such, that shape morality, and determine what desires it would be good for us to feel.

There are, moreover, problems with tying moral obligations as closely to felt desires as Arnhart does. Take psychopaths, characterized by Arnhart as moral strangers because they lack the capacity for the normal range of human sympathies and moral sensibilities. Because of their lack of affect, Arnhart concludes that they lack moral obligations. On his view, it would seem, small children are not morally responsible because they lack developed powers of reason; psychopaths are not morally responsible because they lack developed desires of the required kinds. While this has some plausibility, it is less than lucidly clear that the affective handicaps of psychopaths absolve them of moral obligation. There is at least some force to the objection that a psychopath can know that certain actions are morally wrong and can be held morally responsible for performing them, even if he lacks the motivation to refrain.

Second, Arnhart musters Hume into the ranks of ethical naturalists—and rightly so—in spite of Hume’s fame for having argued that an ought cannot be deduced from an is. Arnhart argues, with some plausibility, that Hume’s is/ought distinction does not cut against the dependence of morality upon human affect. However, Hume emphasized felt desire; Aristotle, I think, was closer to the truth in speaking of the natural ends of human life—i.e., desiderata. One might go further: are there ways we can imagine humanity evolving so that we would have higher or better ends? By what standard should we judge such improvement, and what relevance do the better ends have to the moral standards we should currently apply? One thinks here of Mills reflection: better a Socrates dissatisfied than a satisfied pig. At least these questions seem to be intelligible ones.

Third, there are moral intuitions along these lines that will worry those of us who believe that morality should be impartial. According to Arnhart, a strictly impartial morality is impossible for human beings because our moral sensibilities derive from our social instincts, and these, in turn, are most strongly directed, in the first instance, toward members of our immediate family. They radiate outward to more distant family, community, and nation, in weakening spirals. They extend to all humanity as such in only the weakest way; the interests of those closest to us will always take precedence because our naturally evolved altruistic desires will always be stronger on behalf of our kith and kin.

The argument has some force; but there are two considerations that might prompt one to demur. The first is that our current global circumstances may demand of us a wider set of loyalties and moral commitments that expand the circle of allegiance to all human beings. While our biological instincts may make this shift extremely hard, our intellect may show us that this is the only path to satisfaction of our fundamental needs. Second, the intuition that supports fairness is a deep one, not as closely linked to reciprocity as Arnhart thinks. The demand for fairness has force against the instinct for nepotism because it satisfies our desire for intellectual coherence. We recognize that the sufferings and joys of one person are not intrinsically more significant than those of another because we apprehend in each a common humanity. (Those who support animal rights can with some reason extend this line of argument further. And some mentally handicapped humans have, after all, fewer of the capacities judged by Arnhart to be essential to membership in the moral community than many animals.) The stable suppression of some natural desires is not impossible: witness hunter-gatherer societies, which have endured longer than any other known form of social organization. In them, the desires for wealth, status, and personal prestige are in most known cases studiously suppressed. It is a question of the first importance whether nepotism must always trump a universal humanism—and whether it should.

A fourth large issue concerns the nature of human free will and the reducibility of human consciousness generally to natural causes. With Aristotle, Arnhart argues that living organisms are by nature teleologically organized. Rejecting the reduction of biological explanation to physics, Arnhart claims (p. 239) that the “functioning of a living organism manifests the actualization of its potential for organic form, an actualization that depends upon, but is not reducible to, the natural potentialities of its material elements.” Unfortunately—but perhaps unsurprisingly—Arnhart has little to say about the nature of the crucial “dependence.” Also unsurprisingly, he adopts what, though undeveloped, would most naturally be interpreted as a compatibilist position regarding freedom: it is to have one’s actions determined by one’s deliberate choices. (p. 84)

This is on the whole a well-written book, in spite of an occasional mangled sentence and a certain repetitiousness that permeates its style. The style is very clear, and the discussion is organized in a manner that flows smoothly from one topic to another. As I am not myself a historian of philosophy, I am not able to offer an independent assessment of Arnhart’s historical scholarship. I was pleased to gain from the book a strongly enhanced respect for Aristotle’s often, and unjustly, maligned stature as a biologist and careful observer of the natural world. Arnhart makes use of a wide-ranging, eclectic collection of sources in marshalling his arguments. His book is certainly one to which both friends and foes of naturalistic theories of ethics will have to pay close attention.

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