Charles Darwin has never had a lack of enemies, but today he is more threatened by his own misguided disciples than by any opponents of science. Consider, in the first place, Peter Singer and his call for A Darwinian Left, published in 1999. Singer’s aim is to convince the Left to drop Karl Marx and take up Charles Darwin as its main source of intellectual inspiration. This change is necessary, Singer holds, because the events of the twentieth century have discredited Marx by revealing his inadequate understanding of human nature. Marx dismissed fears that the creation of an all-powerful communist state would lead to tyranny, because he believed that the social and economic transformation that would make such a state possible would also transform human nature so that tyranny would no longer have to be feared. This was a mistake, and, Singer implies, a responsible Left will have to avoid it by embracing a more realistic account of human nature, such as the one offered by Darwinian biology.

To propose such a change of paradigms, however, raises the question of whether the Left can embrace Darwinism while still remaining the Left. Singer thus has to ask: what is essential to the Left, and is it compatible with Darwinism? In answer to the first question, Singer holds that a certain egalitarianism, or concern with equality, is essential to the Left, specifically a concern with supporting the weak and seeking to ameliorate their condition. In answer to the second question, Singer contends that egalitarianism can be made compatible with Darwinism, but only if that egalitarianism is moderated and made more realistic on the basis of what Darwinism teaches us about human nature. For example, the Left’s egalitarianism teaches it to disapprove the competition of the capitalist economy and the inequalities it produces and to desire a more cooperative arrangement. Singer thinks that such inclinations are compatible with Darwin, because Darwinism teaches that human beings have naturally evolved inclinations toward cooperation. Thus there is something in Darwinian human nature with which the Left can work: it can seek to devise social structures that make it easier for our cooperative inclinations to express themselves. Nevertheless, a Darwinian Left will have to be much more modest in its expectations for such a project. For, unlike the older, Marx-inspired Left, which thought that competition was merely a product of social and economic conditions, a Darwin-inspired Left will recognize that there is a competitive and even selfish streak in human nature itself.

While much of Singer’s argument emphasizes the limitations that Darwinism imposes on Leftist aspirations, there is one area in which he suggests that Darwin has something more positive to contribute to the Left, at least indirectly, by way of debunking the assumptions of its enemies. As an example, Singer brings forward the Biblical idea that God gave man dominion over the lower animals. This belief, Singer contends, still influences our thinking even though it has been “thoroughly refuted by the theory of evolution,” which reveals “a continuum between humans and animals,” with respect to both their physical make up as well as their powers of mind. Animals, Darwin showed, “are capable of love, memory, curiosity, reason, and sympathy for each other.” Darwinism therefore eliminates the basis of the notion that human beings are different in kind from other animals, thus preparing a “revolution in our attitudes” toward them. “Darwinian political thinkers,” he concludes, should therefore “be more inclined to recognize, and base policies on, the similarities we identify between humans and nonhuman animals.”

Singer is well-known as a defender of animal liberation, so it is perhaps not surprising that it is here, in relation to some of his most cherished values, that he asks Darwinism to do the most for him. It is precisely where he asks Darwinism to do the most, however, that Singer goes the most wrong. Knowledge of the continuum between humans and non-human animals is less important to the question of a qualitative difference between the two than Singer thinks. Awareness of that continuum is not, I think, as modern a development as Singer believes. Aristotle was aware of it, as were people in the Middle Ages, who believed in a “great chain of being” in which human beings were down with animals pretty close to the bottom. Indeed, this continuum was surely well appreciated even by pre-modern people who had no knowledge of either Aristotle or medieval philosophy. Most pre-modern people, after all, had experience with domesticated animals and were no doubt well aware of animal capacities for thought and emotion. Yet they all still believed in a qualitative difference between humans and non-human animals. They did so very reasonably, on the commonsense understanding that things can be only incrementally different in many respects and yet still qualitatively different in other respects.

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Moreover, Singer is mistaken to think that diminishing the perceived difference between human beings and other animals will result in better human treatment of other animals. If we deny a qualitative difference between ourselves and the beasts, we destroy the basis for assuming qualitatively different obligations to them that go with our special status. Put simply, if we claim that we are not really different than other animals, it is not clear then why we should treat other animals any better than they treat each other. After all, animals themselves are not proponents of animal rights.

A contemporary effort from the Right to derive political guidance from Darwin can be found in Larry Arnhart’s 2005 book Darwinian Conservatism. For Arnhart, contemporary conservatism should take its ethical bearings from Darwinism, which suggests that traditionally conservative principles conform to evolved human nature. Darwinism, Arnhart contends, reveals “at least twenty natural desires that constitute our universal human nature.” These desires, he continues, provide the basis for standards of political right: “If the good is the desirable, then we can judge social practices by how well they satisfy the full range of these natural desires.”

The Darwinian conception of human nature, Arnhart suggests, supports conservative principles across a whole range of issues. For example, Darwinism teaches that human beings are by nature sociable creatures, and therefore joins conservatism in counseling against Leftist efforts to re-engineer social order, which are often based on the assumption that all social order is constructed artificially anyway. Again, Darwinism teaches that human beings are naturally self-interested beings, and thus it supports conservatism in preferring both limited government, since political power is apt to be abused by self-seeking human beings, as well as private property, which accords with our natural self-regard and sense of justice.

Arnhart is correct that Darwin’s realistic account of human nature offers a wholesome restraint on utopian Leftism. Nevertheless, his attempt to ground moral principles only in Darwinian human nature creates a fatal weakness in his Darwinian conservatism. Arnhart plausibly contends that many conservative principles find support in human nature as it is understood by Darwinian biology. But it is also true, given the diversity of our evolved desires, that departures from conservatism correspond to human nature as well. It is fair to say, for instance, that Darwinism lends support to conservatism by showing that private property is not a pure social convention but is based upon an innate human acquisitiveness. This impulse is often accompanied, however, by an equally natural propensity to seize the property of others by force. Arnhart himself concedes this by listing “war” as a natural human inclination, noting that human beings have an inherent tendency to use force to advance group interests. Accordingly, Darwin thought property was grounded in human nature, but simultaneously held that “stealing from strangers outside one’s own society might be permitted or even honored.”

An adequate account of private property calls for respect for the rights of other human beings by virtue of their humanity. Darwinism cannot foster such respect, however, because Darwinian morality is tribal in character. Arhnart’s Darwinian conservatism rests on the sociable emotions, but Darwin himself held that “the social instincts never extend to all the individuals of the same species.” Its evolutionary origins confine human sociability to the small group. After all, according to the evolutionary account of human origins, our capacity for morality grew out of our need “to cooperate within groups in order to compete with opposing groups.” As a result, our complement of moral passions includes not only a rather narrowly focused sympathy, but also an active hostility towards outsiders—those that we may need to harm or kill in the pursuit of our own group interests. Hence Arnhart’s observation that “our sympathy is not indiscriminate…we feel more attachment to those close to us,” and “our disposition to distinguish friends from enemies” sometimes “inclines us to be cruel to outsiders.” Because such cruelty is no less natural than sympathy, it is—at least for a purely naturalistic ethics such as Darwinian conservatism—just as good as sympathy. Needless to say, it is difficult to gain clear moral guidance from a doctrine that counsels us to follow our nature—while adding that industry and theft among individuals, and commerce as well as war among nations, are equally natural undertakings.

Why, we may wonder, have efforts to find political prescription in Darwinian biology so consistently foundered? I would suggest that the difficulty is inherent in the undertaking, and not merely the result of secondary errors in reasoning that future Darwinian political theorists might avoid. As John Dewey correctly observed, modern science, of which Darwinism is a part, emerged as a rejection of an older natural science concerned with the natural purposes or ends of things, and hence with what could be considered their natural flourishing. The founders of modern science thought this older quest had proven futile, and so they set out instead to acquire a humbler but more certain knowledge—knowledge of where things come from and what they are made of. Modern science has in fact achieved an impressive mastery in this realm, and its success has given it great social respectability.

It is understandable that we would be tempted to get the authority of modern science, including Darwinism, on the side of our preferred political positions. The attempt to do so, however, involves using scientific data to draw conclusions about matters—the just and the good—about which modern science expressly disclaims any pretensions to knowledge. Biological nature as empirically observed necessarily includes phenomena that we find good as well as phenomena that we think bad. Thus efforts to derive moral guidance from modern empirical science’s account of biological nature necessarily involve preferring, on non-scientific grounds, some aspects of nature to others. This results in the formulation of normative political theories, on both the left on the right, that claim a scientific status that they in fact only appear to possess. Such false appearances introduce not scientific enlightenment but philosophical and moral confusion into our public discourse, and so both liberals and conservatives would do better to resist the temptation to seek such “scientific” credibility for their policy recommendations.