In the Declaration of Independence, Thomas Jefferson appealed to “the laws of nature and of nature’s God” as the grounds for natural justice. But what happens when many people decide that belief in an eternal Creator or in a natural order shaped by such a Creator is an illusion? If the universe has no cosmic meaning or purpose, can we give our lives moral dignity by creating and then obeying our own norms for thought and action? Or must this idea of the moral emptiness of the universe have degrading effects on human life?

In 19th-century Europe and America, the apparent decline in religious belief and growth in scientific materialism led many thinkers to ask such questions as they worried that the loss of faith would bring a moral, intellectual, and political crisis. The most provocative manifestation of that crisis was in the writings of Friedrich Nietzsche, who proclaimed that “God is dead.” He warned that Europe was approaching a nihilist catastrophe in which human beings would have to choose how to live without knowing that any choice is ultimately better than another. To escape the emptiness of their lives, some people would distract themselves by pursuing a soft life of petty pleasures. Others would choose to satisfy their desire for domination by tyrannizing over others.

Charles Darwin’s theory of evolution seemed to many people to support Nietzsche’s position. In one of his early notebooks, Darwin wrote: “Man in his arrogance thinks himself a great work, worthy of the interposition of a deity. More humble, and I believe true, to consider him created from animals.” What are the moral consequences of doubting the traditional religious belief that human beings were created by God in His image, and believing instead that human beings were “created from animals”? Many of Darwin’s critics worried that this would destroy morality by denying the transcendent grounds for the moral dignity of human beings as set apart from, and above, everything else in the material universe. Darwin himself, however, denied this, because he agreed with Jefferson that human beings were endowed with a natural moral sense. In The Descent of Man, Darwin explained how this moral sense was instilled in human nature as shaped by natural selection in evolutionary history.

Furthermore, although Darwin was evasive about his personal religious beliefs, he consistently affirmed that his account of evolution by natural selection left open the possibility that God acted as First Cause in bringing the universe into existence out of nothing. If all of nature is ultimately God’s creation, then there is nothing ignoble in the origin of human beings as “created from animals.”

For many observers, the first half of the twentieth century manifested the disastrous consequences of Nietzschean atheism and Darwinian materialism. In World War I, some German militarists spoke openly of their view of the world as governed by “the will to power” and “the survival of the fittest.” In World War II, Adolf Hitler’s Nazis combined the nihilism of Nietzschean philosophy and the racism of social Darwinism. In the second half of the twentieth century, however, history seemed to turn in favor of liberal democratic regimes based on natural rights. First the defeat of the fascist and Nazi regimes and then the collapse of the major Marxist regimes seemed to vindicate the strength of liberal democracy.

Francis Fukuyama’s famous article of 1989 in The National Interest—“The End of History?”—offered a philosophic explanation for this. History as the human search for the fully satisfying social order had come to an end, Fukuyama declared, because most people around the world today agree, at least in principle, that liberal democracy is the only fully satisfying social order. To be sure, there will be some resistance to liberal democracy in certain parts of the world—Islamic fundamentalism, for example. But Fukuyama argued that although such resistance will create international conflict, this will only delay the inevitable victory of liberal democracy. He explained that there is an enduring human nature that includes natural desires—such as the desire for material comfort and the desire for social recognition—which human beings can fully satisfy only in a liberal democracy.

And yet Fukuyama has often vacillated on the question of whether this argument can withstand the challenges coming from Nietzschean philosophy and Darwinian science. After all, if there are no eternal standards of right and wrong dictated by God or nature, what prevents a Nietzschean Superman from asserting his will to power over others? Why shouldn’t we use the power over nature that comes from modern science to alter human nature in ways that would satisfy everyone? Aldous Huxley’s Brave New World showed how modern science could be used to breed a race of dominant masters to rule over their happy slaves.

One of the objections to Fukuyama’s original “end of history” argument was that we have not yet reached the end of history because we have not yet reached the end of science. Particularly in the life sciences, our growing knowledge of—and power over—human nature will create an unprecedented moral crisis as we decide whether and how we want to use biotechnology to change human nature. In an article in 1999 in The National Interest—on the 10th anniversary of his “End of History?” article—Fukuyama admitted that this was the one objection to his original article that he could not answer. His new book, Our Posthuman Future, is his answer to this fundamental challenge.

Fukuyama begins his book by acknowledging the power of Huxley’s vision of the end of history. Life in Brave New World is so seductively attractive that it is hard to see the evil. Reproductive technology and medical science are used to make sure that everyone is happy, healthy, and adapted for their role in society. People have been bred in hatcheries to have the abilities and propensities of a particular caste to serve the collective welfare of the world state. The biological family is abolished so that no one is disturbed by the emotional stress of familial responsibilities and conflicts. Sexual gratification is accessible to all. There are specific government agencies to make sure that every desire is satisfied. There is no religion because no one has any transcendent longings. When people feel depressed or anxious, they can take soma, a psychotropic drug that induces states of dreamy euphoria. No one reads Shakespeare, because he assumes a world of pain, struggle, conflict, and longing that is incomprehensible to the happy people of Brave New World.

Of course, we all know what’s wrong with these people. Although they may be healthy and happy, they are no longer fully human beings. “Their world has become unnatural in the most profound sense imaginable,” Fukuyama observes, “because human nature has been altered.” Fukuyama insists that we cannot stop here, however, because there is a deeper question. Why should we want to preserve our human nature as traditionally understood if we have the power through biotechnology to change it in ways that would make everyone healthier and happier?

One answer would come from Biblical religion. Since human beings have been created in God’s image, and this is the ground of their moral dignity, it would violate God’s order and deprive human beings of their sacred worth to radically change what God has ordained.

Although Fukuyama respects this appeal to religious belief, he thinks that human nature itself should provide its own ground for resisting a move towards “posthumanity.” Human nature sets the foundation for moral experience, and therefore we should be cautious about using biotechnology in ways that would deprive us of that ultimate source of value in our human nature. He identifies this position as Aristotelian, which suggests a secular philosophic stance that does not depend on religious belief. He explains: “Aristotle argued, in effect, that human notions of right and wrong—what we today call human rights—were ultimately based on human nature.” Believing that “the good was defined by what people desired,” Aristotle thought that to understand moral experience we must understand “how natural desires, purposes, traits, and behaviors fit together into a human whole.” By appealing to the natural desires as morally decisive, Aristotle was like the utilitarians. But unlike the utilitarians, Aristotle did not reduce all natural desires to some simple desire to maximize pleasure and avoid pain. Rather, Aristotle saw the moral problem as a matter of deliberately organizing the complex and diverse ends of human beings in order to satisfy the full range of natural desires over a whole life. Fukuyama’s book is an elaborate argument for his Aristotelian moral appeal to human nature—particularly, as constituted by the natural desires—to guide us in regulating biotechnology.

In the first part of the book, Fukuyama surveys the recent advances in the biological sciences that promise a future power to change human nature through biotechnology. The brain sciences are giving us greater understanding of how the mechanisms of the brain shape human thought, emotion, and behavior. Neuropharmacology allows us to control brain states—including the cognitive and affective components of personality—through psychotropic drugs such as Prozac and Ritalin. The biological understanding of the aging process will probably lengthen the human life span in ways that will alter our traditional views of life and death. The ultimate power over human nature would be to use genetic engineering to modify the DNA in human embryos in ways that would be passed on to future generations. Although this power might be far off in the future, we already have the power through in vitro fertilization to allow parents to choose which embryos they want to implant in the mother’s womb based on genetic analysis of the embryos available. Increasing precision in genetic analysis of the DNA in embryos could eventually lead to “designer babies” that would reflect the deliberate choices of parents about the genetic nature of their children.

As was true for eugenics programs in the early part of the twentieth century, the scientific breeding of human beings in Huxley’s Brave New World was carried out by government through coercive measures. Such involuntary programs arouse such repugnance today that it is unlikely that we will ever again allow such governmental projects. But that leaves open the possibility of a new form of eugenics carried out through the voluntary choices of parents who use biotechnology to produce the kind of children they want. Libertarians who would resist state-sponsored eugenics often see nothing wrong with leaving parents free to employ whatever reproductive means science and the medical marketplace provide. Fukuyama rightly sees this as the great challenge for those who would resist the new eugenics: they must explain what harm there can be in allowing parents to freely decide the genetic character of their children.

Religious objections to “playing God” might restrain some parents, but such objections will not prevail with those who do not share such religious beliefs. Utilitarian concerns about the physical harm to children that might come from new reproductive techniques will impose some restraint, but utilitarian considerations of costs and benefits usually give little weight to the subtle psychological consequences of unnatural reproductive procedures that might have dehumanizing effects. If the ultimate danger is the loss of our humanity, then we need some explanation of the human essence, of how we might lose it, and why we should worry about losing it.

In the second part of his book, Fukuyama tries to explain the essence and the importance of human nature. Modern liberal democracy depends on the moral appeal to “human rights.” But “human rights” implicitly depend on an understanding of “human nature” as possessing “human dignity.” So, for example, the idea that human beings have a right to life assumes that the desire for self-preservation is a part of human nature that cannot be denied without denying human dignity. Even those libertarians who think human liberty should not be constrained by notions of human nature must themselves implicitly appeal to human nature. Those who speak of the “reproductive liberty” of parents assume that this liberty has moral status because it expresses a natural desire to produce and care for children that is so central to human nature that we should respect it.

To sustain his argument, Fukuyama must show how the desire to have children is only one of many desires that belong to human nature, and then he must show how the free use of biotechnology could distort that human nature in a dehumanizing way. Although his account of human nature is sometimes confusing, his final conclusion is that the essence of human nature is not some single factor such as reason, language, moral choice, or emotions but all of these traits brought into a “human whole.” The aim in regulating biotechnology should then be preserving the integrity of this “human whole” from unnatural distortion.

In the last part of his book, Fukuyama lays out his practical arguments for regulatory policies governing biotechnology. It is commonly asserted that any attempt at governmental regulation of biotechnology will be futile, because people will find ways to evade the laws, and countries with strict regulations will simply drive people to other countries where scientists and entrepreneurs are free to satisfy the demand for the latest techniques. Fukuyama rejects this reasoning. He argues that there are many cases of scientific technologies that have been successfully regulated by the international community. The many examples would include nuclear weapons, nuclear power, biological and chemical weapons, neuropharmacological drugs, and genetically modified foods. Of course, in each case, the regulation is imperfect. But the fact that legal rules can only be imperfectly enforced is no reason not to have the rules. After all, as Fukuyama observes, the laws against murder have never completely eliminated murder, but every society needs such laws.

Fukuyama does not recommend a specific set of rules for regulating biotechnology. But he does argue for a general policy of allowing biomedical techniques to be used for “therapeutic” purposes, while banning or restricting their use for “enhancement” purposes. Although he concedes that the distinction between “therapy” and “enhancement” is fuzzy, he insists that the distinction is still real, and it’s the kind of distinction that lawmakers and regulators often make as a matter of practical judgment.

Fukuyama’s book is a brilliant exposition of what he calls “the natural right approach” to biotechnology. For those of us who find such an approach attractive, this book provides an intellectual road map for thinking our way through the deepest moral and political debates of the 21st century.

To apply natural right reasoning to biotechnology, we will need to think more about at least four points where Fukuyama’s reasoning is somewhat vague. He is vague about human nature. He is vague about religious belief. He is vague about the substantive content of his regulatory policies. And he is vague about whether Nietzsche’s attack on natural right succeeds.

Reviewers of Fukuyama’s book have noticed that although he relies on human nature as the ground of morality, he is vague about the content of human nature. J. Bottum, writing in The Weekly Standard, complained that Fukuyama does not give us the “thick account of human nature” that we need.

Fukuyama acknowledges my book, Darwinian Natural Right, in which I list 20 natural desires that are universal elements of human nature. I argue that if the good is the desirable, as Aristotle says, then morality can be rooted in the human nature of these natural desires. Moreover, Darwinian biology can explain these natural desires as part of human biological nature. Thus, Darwin’s argument for a natural moral sense supports Aristotle’s conception of natural right. While Fukuyama’s Aristotelian “natural right approach” as rooted in human biology would seem close to my position, he rejects my list of 20 natural desires. “Such lists,” he writes, “are likely to be controversial; they tend either to be too short and general, or overly specific and lacking in universality.” He then explains: “More important than a comprehensive definition for our present purposes is an effort to zero in on characteristics that are unique to the species.” What we need to know, he says, is the “Factor X” that makes human beings unique in a way that gives them moral dignity. He then goes through a list of possible traits that would qualify as “Factor X”: reason, language, consciousness, moral choice, human emotions, and other factors. But he finally concludes that what is decisive is not any one of these traits but the full gamut of traits that constitute “the human whole.” This is confusing, because if one looks at his list of human traits, it corresponds closely to my list of natural desires.

I say that human beings naturally desire to care for children. And Fukuyama repeatedly speaks of parental care as a natural desire. I say that human beings naturally desire social ranking. And Fukuyama stresses the striving for social recognition as a natural desire. I say that human beings naturally desire political rule. And Fukuyama agrees that human beings are political animals by nature. Indeed, all of the 20 natural desires on my list appear in Fukuyama’s account as elements of human nature. It is hard for me to understand how he can defend his notion of the “human whole” without embracing these natural human desires.

I also argue that human beings have a natural desire for religious understanding. But Fukuyama is vague about the role of religion. He says that human nature “conjointly with religion” is “what defines our most basic values.” Yet he also says that he relies on “reasons that have nothing to do with religion,” and that he defends “a concept of human dignity that does not depend on religious assumptions about the origins of man.”

He quotes the claim of Pope John Paul II that there must be an “ontological leap” in the evolutionary process leading to human beings, in which the human soul is directly created by God, and that without this, it is impossible to maintain human dignity. Fukuyama is not clear whether he agrees with this or not. He speaks of the appearance of human consciousness as an “emergent” process in which properties arise at higher levels of complexity that cannot be fully reduced to lower levels. This seems to disagree with the Pope, who explicitly rejects explanations of the human mind as a product of natural “emergence.” Fukuyama concludes: “The problem of how consciousness arose does not require recourse to the direct intervention of God.” But then he immediately adds: “It does not, on the other hand, rule it out, either.”

One way out of this confusion over the role of religion, which Fukuyama suggests in a few passages, would be the way taken by Jefferson and some of the other American Founders. If there is a natural moral sense, then secular reason and religious belief can agree on morality. Even when diverse religious traditions come into conflict over theological doctrines, they should be able to agree on morality. And insofar as this morality is rooted in the desires of human nature, it should be knowable by purely natural human experience even without the benefit of revelation.

Appealing to a natural moral sense is essential for resolving moral disputes over biotechnology where the theological claims are neither clear enough nor persuasive enough to provide a common ground for the whole community. Fukuyama tries to evoke this moral sense in laying out his regulatory policies, but the content of his proposed policies is often vague. Struggling with the question of when human life begins, he finally concludes by taking the middle ground. “While an embryo can be assigned a lower moral status than an infant, it has a higher moral status than other kinds of cells or tissue that scientists work with.” But he refuses to specify a policy for handling potential human life before birth. This could be defended as an intelligent vagueness that leaves room for such questions to be settled by prudential judgment and the political process of deliberative debate. Fukuyama is now participating in that political debate as a member of President Bush’s Council on Bioethics, chaired by Leon Kass.

Fukuyama is clear in recommending a complete ban on human reproductive cloning. But he is unclear about the reasoning supporting this. He declares that “cloning is a highly unnatural form of reproduction that will establish equally unnatural relationships between parents and children.” It is “unnatural” because of the “asymmetrical relationship” that the cloned child will have to the parents—being the identical twin of one parent but completely unrelated to the other. He then stops without elaborating or defending his reasoning, which leaves the reader wondering about his argument. A reader might wonder, for example, how the “asymmetrical relationship” of stepchildren to their parents differs from what would arise from cloning.

Finally, Fukuyama is vague about his stance toward Nietzsche. The epigram for his book is a quotation from Nietzsche. Of the nine epigrams heading some of his chapters, five are quotations from Nietzsche. Yet he never explains the Nietzschean character of his argument. The few comments he does make about Nietzsche undercut his argument for Aristotelian natural right by suggesting that Nietzsche’s attack on natural right might turn out to be correct. After speaking about the “human moral sense,” he says: “It may be the case that, as Nietzsche predicted, we are fated to move beyond this moral sense. But if so, we need to accept the consequences of the abandonment of natural standards for right and wrong forthrightly and recognize, as Nietzsche did, that this may lead us into territory that many of us don’t want to visit.” Such talk of being “fated” to move towards “the abandonment of natural standards for right and wrong” manifests a Nietzschean historicism that runs throughout much of Fukuyama’s writing.

I have never found any proof in Nietzsche’s writing that we are “fated” by history to go “beyond good and evil.” I see no reason, therefore, to reject the claim of Aristotle, Jefferson, and Darwin that there is a natural moral sense rooted in human biological nature. The coming debates over biotechnology will test the strength of that moral-sense tradition. We could strengthen the moral-sense argument in the modern world by combining an Aristotelian conception of natural right and a Darwinian biology of human nature so that we could appeal to Darwinian natural right.