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Humans, Nature, and Ethics

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Does the idea of “nature” provide any kind of ethical touchstone to guide and to limit human impacts on ecosystems or the biochemical basis of life?  And does the idea of “human nature” similarly provide any kind of moral structure to govern our use of biotechnological means to alter human beings?  Many would say no to both questions too quickly, just as many others would too quickly say yes. I believe that we must take a more complex and nuanced position on these fundamental questions. To argue against something—such as hu­man applications of biotechnology for enhancement of traits—because it will change human nature or is unnatural implies that we know what human nature is, when surely human nature is amorphous and slip­pery at best. The difficulty of pinning down human na­ture is one reason that attitudes about nature cannot be plausible unless they are limited and complicated.

In this essay, I argue that we may not need to know much about human nature to have moral concerns about changing it by means of biotechnology. Neither our conception of nature nor our conception of hu­manity need to be—or can plausibly be—essentialist and static. To attach moral significance to the condi­tions of our humanity, and to be wary of the techno­logical manipulation of it, we do not necessarily need to specify exactly what it means to be human. We do not need to have a full theory of human nature in order to have moral concerns about changing it.

Essentialist Versus Evolutionary Perspectives

According to one influential philosophical tradi­tion, to understand human nature is to grasp the es­sence of what it is to be human. As typically under­stood, an “essence” is the fundamental being or reality that a particular thing embodies. An essence explains the traits that a thing has. It is not reducible to those traits, however; it is unchanging and timeless. An es­sence has an existence of its own, and indeed it is, in a sense, more real than the items that partake of it. Further, essences are often held to relate things of dif­ferent kinds to each other. An essence connects indi­viduals into a larger class or kind; all the members of a given kind share an essence, and members of other kinds lack it. According to an ancient lineage of schol­ars whose work draws on Aristotle, a kind is what it is by rational necessity. It is part of this view that the overall universe is rationally ordered and necessary, and we can understand the order and necessity of the universe by grasping the essences that things in the universe embody.

However, essentialism is not the only way of un­derstanding the concept of “human nature.” An alter­native view, now salient in all post-modern thought and very significant in the biological sciences, is non-teleological evolution, pioneered by Darwin. When applied to the study of human beings, an evolution­ary view makes no claim for the rational necessity of human nature, or for its immutability and timeless­ness; nor does it claim that an account of human na­ture will show that human nature is rationally related to the rest of the universe. There need also be no requirement that what makes humans human is some trait that the members of other species entirely lack. Typically, looking at traits allows one to recognize spe­cies, but the traits that allow us to recognize humans as humans might be found in some measure in other animals. And ultimately, in an evolutionary account, what really distinguishes species is not any claim about what traits characterize the members of the spe­cies, but the causal story that can be told about how the species appeared on the scene and how, through reproduction, it persists.

On an evolutionary view, then, “human nature” does not refer to an unchanging essence. Instead, it describes functions; it tells us what the members of the kind happen to be like. From this perspective we should expect to better understand human nature by studying our taxonomic neighbors, as Mary Midgley argues in Beast and Man. What distinguishes human beings from other animals is typically held to be their possession of various capacities related to cognition, such as language, rationality, tool-making, morality, and culture, but there is no need to establish that any of these capacities are possessed only by humans; in­deed, the evidence is mounting that they are capacities or extensions of capacities that animals also possess in differing forms and degrees. At the same time, as Midgley also emphasizes, we need not restrict our­selves to biology to learn about human nature. We will have to study humans sociologically and anthro­pologically, as Paul Ehrlich does in Human Natures: Genes, Cultures, and the Human Prospect, in which he argues that there is no unitary account of human nature, and that, given the significance of culture in human ways of living, there are instead multiple hu­man natures.

Moreover, the idea of “human nature” can refer both to how individual human capacities are acquired and to general claims about human capacities. Human bodies and faces tend to look a certain way, and that is a fact of nature. But there is also a surprising degree of variation, and that, too, is a fact of nature. Plainly, there is no single, overarching definition of “nature” that applies to all of the ways in which the term is used and always shows clearly what the correct usage is. However, both in rejecting the essentialist under­standing of “human nature” and in allocating only a limited role to assertions about human species norms, we shift the focus from general claims about what hu­man beings are like to a recognition of diversity, com­plexity, and individual variation. To do so is to give up pretensions to a commanding knowledge of what human beings are really like.

Human Nature as the Basis for Morality

The moral concerns people have about modifying human nature are also various. Like the different views about what a concept of human nature is, views about the connection between human nature and moral val­ue can have diverse implications for what one knows about human nature.

Here I want to consider the view that the concept of human nature represents the very foundation for morality. This view implies that, if our understand­ing of human nature was erroneous or incomplete, then many of our moral judgments would be unreli­able. Everyone agrees that an adequate understanding of human nature is necessary in order to ensure that moral judgments square with the facts on the ground. For example, if we recommend punishment because we believe that it helps people rehabilitate themselves, but that belief is mistaken, then our judgments about punishment are unreliable. Our values lead to specific moral positions only in light of premises concerning relevant facts. But if human nature is understood as the very basis for morality, then our moral judgments may be wrong not only on factual premises but on val­ues trait premises as well. Thus, to the extent we think we know what our values are, we must have a command of hu­man nature.

Leon Kass is often thought to provide a clear example of this way of thinking about the moral relevance of human nature. Kass himself explicitly de­nies this view.[1] More­over, his method is not what one would expect if this were his view. The natural method for basing moral guid­ance directly on human nature would be first to set out an account of human nature and then to apply it as needed, but Kass’s method is typically to start by considering questions of meaning. In a chapter about the creation of human embryos in the laboratory, the philosophical discussion begins with a section subti­tled “The Meaning of the Question,” and Kass explains that his “orientation” is “that before deciding what to do, one should try to understand the implications of doing or not doing.”[2]  Kass then connects these, not to an account of human nature, which would offer vari­ous claims about what humans are, but to the “idea of humanness,” which is a question of how we think about ourselves—a topic for poetry as much as for science.

This method seems to commit Kass only to a limited theory of human nature. He is making claims about what is species-typical for humans, but the claims do not amount to a complete ac­count of what is human and what falls outside the category. Moreover, many of the claims he of­fers are about such basic features of human life—sexual procreation, growing old, and passing away—that they encompass not only all humans but all animals. Kass’s theory is best rebut­ted not by challenging his theory of human nature but by challenging the claims he makes about its moral relevance.

Nonethless, there are glimmers in Kass’s writings of a grander vision.  He has a tendency, for example, to speak broadly of human nature as a kind of touchstone or guiding light in thinking about biotechnology.  “Beyond Therapy,” a report from the President’s Council on Bioethics, and heavily influenced by Kass, asserts that “only if there is a human ‘givenness,’ or a given humanness, that is also good and worth respecting, . . . will the ‘given’ serve as a positive guide for the choosing what to alter and what to leave alone.”[3]  Also, it is striking that Kass reaches skeptical conclusions about enhancement every time he considers it; though the method is case by case, the underlying agenda is general.  If human nature is not a straightforward moral guide, it nonetheless provides something close to a guide.  Finally, there is an undercurrent in Kass’s writings of essentialism.  Kass emphasizes the limits of science and empiricism and the room, and need, for alternative ways of apprehending human life.  “Our current evolutionary orthodoxy,” he notes, “has, in fact, little to say about the true origin of life or about ultimate causes, not only of life but of all major bio­logical novelty. It cannot account for the emergence of higher organisms.” We need to turn, Kass tells us, to “unorthodox biologists,” and in particular to Aristotle, “who emphasized questions of being over becoming, form over matter, purposiveness over moving parts, and wholes over parts; for whom the soul was not an ethereal spirit or a ghost-in-the-machine but an im­manent and embodied principle of all vital activity; and for whom science was a refined and ever-deepen­ing reflection on the natures and causes of the beings manifest to us in ordinary experience.”[4]

It is hard to read such passages without conclud­ing that Kass thinks, at some level, that the cosmos is rationally ordered; that humans—highest of the higher organisms—have their proper place in the overall order; and that understanding their nature is not merely a matter of collecting observations about what humans are like, but also of gaining special in­sight into larger mysteries.[5] These grander ambitions for deploying the concept suggest a commitment to a much stronger theory of human nature than Kass ever attempts to provide.

Human Nature as a Condition of Morality

Another way of thinking about the moral relevance of hu­man nature is to see it as a logical requirement of (human) moral­ity. Francis Fukuyama takes this approach. Fukuyama is also the clearest case of some­one opposed to enhanc­ing human nature who rests the argument on an overarching theory of human nature. Fuku­yama famously claims that human nature “is the sum of the behav­ior and characteristics that are typical of the human species, aris­ing from genetic rather than environmental factors.”[6] Thus, humans are distinguished by an overall set of traits, rather than by any one trait; Fukuyama does not attempt a complete list. In fact, the set would have to be somewhat indeterminate, if only because any at­tempt to specify “fundamental facts” tends to be in­determinate. Further, the set will consist of ranges of traits rather than precisely specified traits. Because traits are a function of environmental as well as genet­ic factors, the set of traits “arising from genetic fac­tors” will be unstable; “normal human height,” for example, can change over the generations due to changes in diet. None­theless, out of this overall general understanding of the range of traits pos­sible given the human genome emerges what is distinctively human, which Fukuyama calls “the hu­man essence” or “Factor X.” This is not itself a trait but an emergent property that depends on the entirety of human traits. Thus, though Fukuyama holds that human nature is definable, he does not hold that we can easily articulate human nature:

If what gives us dignity and a moral status higher than that of other living creatures is related to the fact that we are complex wholes rather than the sum of simple parts, then it is clear that there is no simple answer to the question, What is Factor X? That is, Factor X cannot be reduced to the possession of moral choice, or reason, or language, or sociability, or sentience, or emotions, or consciousness, or any other quality that has been put forth as a ground for human dignity. It is all of these qualities coming together in a human whole that make up Factor X.[7]

Fukuyama’s problem with enhancement technolo­gies is that if we shift human nature beyond the pale of the traits that our genes make possible, then we will disrupt our understanding of human dignity and, therefore, of human rights. Given his understanding of “the human essence” as emergent from the over­all set of human traits, Fukuyama maintains a broad opposition to enhancement. “What is it we want to protect from any future advances in biotechnology? The answer is, we want to protect the full range of  our complex, evolved natures against attempts at self-modification.”[8] In other words, it is not only language and rationality but also the entire set of behavioral and physical characteristics that concerns Fukuyama.

I believe that the core problem with Fukuyama’s argument is that he attaches value primarily to human species norms, with the added complication that he sees the norms as established genetically. We have to be able to enumerate the traits we must watch, fix their appropriate ranges, and sort out the genetic contribu­tion to them. But getting a handle on all this—and then sorting out the genetic versus the environmental con­tributions to the traits we choose to track—has proven difficult. Another weak spot is Fukuyama’s flirtation with essentialism. His broad and stringent set of traits that should not be genetically modified amounts to an attempt to define decisively what falls into the human category and what falls outside. But this will give some perplexing results.[9] It may imply, for example, that Shaquille O’Neal, whose height is certainly anomalous, is not fully human. Fukuyama is aware of this danger, and he takes pains to emphasize that traits vary greatly and that gene-environment interactions can shift the entire range of traits over time. In that case, however, enhancement that does not bump a person beyond the range of normality might be unobjectionable, and en­hancement that shifts someone outside the range of normality might not always make human dignity and human rights inapplicable. Enhancement would seem to pose a problem only when it occurs often enough and dramatically enough to pull apart the statistical curves that describe normal ranges of human traits. It is broad social trends that we are really concerned about, not individuals.

A non-essentialist version of Fukuyama’s general approach seems possible. Paul Lauritzen argues that if biotechnology can significantly change human ca­pabilities and life trajectories but is not available to most people, then it risks undermining our common sense of humanity, which could undermine the capac­ity for human sympathy.[10] The starting point for this thought is that human identity is bound up with hu­man biology, such that “a new biology might give rise to a new psychology.” A new psychology would lead, in turn, to a new ethics. In particular, worries Lauritzen, it would challenge our conception of human rights. “The most persuasive account of human rights,” he writes, “is framed in relation to the notion of a stable human nature.” The fear, then, “is that biotechnology will change the species-typical characteristics shared by all humans. If that happens, and if rights are tied to a conception of human nature that is in turn rooted in a biological reality, then biotechnology threatens the very basis of human morality as we know it.”

In Lauritzen’s view, then, it is critical to human morality that there is a stable human nature and that humans all recognize that there is a stable human mo­rality. Lauritzen is not concerned with determining what is inside and what is outside the human catego­ry. His point is only that we must have some ability to describe important human characteristics that people of different races, ethnicities, sexes, and nationalities share in roughly the same measure.

The Relationship between Humans and Nature

Another way of arguing for the moral significance of human nature is to argue that a certain kind of re­lationship to it is morally significant. Michael Sandel and Jürgen Habermas exemplify this approach. San­del argues that a certain relationship to human na­ture is both valued in itself and vital for various things that we value in human society, and Habermas claims that a certain relationship to human nature is vital for equal membership in the moral community.

Sandel’s argument for worrying about en­hancement is broad ranging, and in places he seems to develop arguments that follow conse­quentialist lines. His primary argument, though, is that certain ways of using enhancement lead to an imbalance in two sorts of relationships to hu­man nature—an accepting relationship, in which we see nature as a gift, and a perfectionist rela­tionship, in which we strive to improve it. The ide­al is to hold these in tension with each other, but enhancement pushes us away from the first and toward the second. Widespread use of enhance­ment would “represent the one-sided triumph of willfulness over giftedness, of dominion over rev­erence, of molding over beholding.”[11]

Sandel goes on to say why losing “the ethic of gift­edness” would be unfortunate. Losing the ethic of giftedness would undermine “three key features of our moral landscape—humility, responsibility, and solidarity.” This claim could be understood as a con­sequentialist point—if we lose these key constraints on our behavior, many people will end up worse off—or it might be understood as pointing out conceptual implications—if we lose these aspects of the “moral landscape,” we could not but feel that as a huge loss. Sandel plainly hopes, though, that many of his readers will feel the loss of giftedness itself already as a loss. It is partly to show the import of losing giftedness it­self that he tries to show how it is bound up in sports and in parenthood, such that if we lose the ethic of giftedness, then sports and parenthood will be dimin­ished—“the drive to banish contingency and to master the mystery of birth diminishes the designing parent and corrupts parenting as a social practice governed by norms of unconditional love.”[12] Sandel’s argument is not limited to sports and parenthood, however; he intends these discussions to exemplify a larger point about giftedness.

For my purposes, the important point is that San­del can speak of the human relationship to bodily nature without making any overarching claim about human nature itself, other than that the traits people have depend on the bodies they have, and that tradi­tionally people have acquired their bodies—and, there­fore, their traits—through contingent processes rather than through design. The point of giftedness is that we do not know exactly what to expect in human nature, so we should foster what Sandel, borrowing from Wil­liam May, calls an “openness to the unbidden.” But such claims fall well short of a theory of human nature.

Contingency is also critical in Habermas’s case against enhancement. We are able to live together in communities and engage each other as equals because we all share some sort of “pri­or ethical self-under­standing”—an under­standing of who we are that makes it possible for us to see ourselves as “ethically free and morally equal beings.”[13] The critical element in this self-understanding is an awareness that we are embodied and that our bodies are our own, in the sense that we do not acquire them from other people; they are products of fate or na­ture rather than of other members of the community. In short, the contingent nature of a person’s traits is a condition of being one’s own person—of having au­tonomy, having unique worth, and being a member of equal standing in the moral community. We must be able to assume that “we act and judge in propria per­sona—that it is our own voice speaking and no other.”[14]

Habermas worries that this assumption is at risk if a child knows that she has been genetically enhanced by her parents, for then the parents’ goals are present directly in her body. The processes of childrearing and socialization may also impose the parents’ goals on the child, but the child can in principle reject these, and Habermas supposes that such goals will not be pres­ent in the child’s body in the same way. Of course, the child might accept her parents’ goals as her own, and if she does, she will not feel deprived of her own voice. But because we cannot be sure that children’s and par­ents’ goals will harmonize, genetically enhancing chil­dren “jeopardizes a precondition for the moral self-understanding of autonomous actors.” Thus, parents should approach parenthood with an “expectation of the unexpected.”[15]

Whether either Sandel’s or Habermas’s concerns are ultimately persuasive depends on pursuing moral and political questions that lie beyond the scope of this essay. Sandel’s argument could be understood simply as identifying and defending a personal moral ideal, one that many people share and that Sandel wants to recommend, but that he would not seek to enforce through public policy. Habermas, however, must be aiming at public policy. To wrongly prevent some peo­ple from joining the moral community is to commit a grave injustice that must be opposed by law.

Both positions rest on claims about human na­ture that are modest and defensible. Neither is mak­ing any claims about human beings’ essential nature. Nor are they arguing that a normal human range of traits is what we value. Rather, it is the relationship of each person to his or her own nature that Sandel and Habermas are concerned about.

The key point Habermas wants to make is that to be a person is to exist in a body that is one’s own and is not the directed creation of other people (or of the community as a whole). The bodies of free and equal persons do not incorporate the intentions of other members of the community. To establish this concern and perspective, Habermas need not thoroughly cata­logue the traits that make up human nature, nor come up with a definition of human nature that sets out a criterion for those traits. Further, Habermas’s empha­sis on contingency does not imply that human nature is fixed. It might indeed change, but the change must itself be contingent. Natural evolution seems accept­able, for example. The constraint Habermas would impose is only on how the change occurs; some mem­bers of the community should not be able to deliber­ately intervene in the bodies of other members.

The complexity of the genes’ contribution to ac­tual human life may qualify Habermas’s and Sandel’s concerns about modifying children. Parents’ success at using genetic technologies to make their children turn out one way rather than another is likely to vary greatly, depending on what traits they have in mind for their children, and it may well be that a majority of the traits parents would want to produce lie beyond ge­netic control. It does not take complete success at con­trolling a trait to raise concerns, however. Completely controlling a trait might be the limit case. Habermas would be troubled if an intervention falls short but leaves a lasting reminder for the child, on the child, of what the parents wanted the child to be. Sandel’s worry that the child is not regarded to a sufficient de­gree as a gift depends on the parents’ attitudes, which (Sandel supposes) depend in part on parents’ capacity to carry out their own plans. But parents might fail to regard a child as a gift even though they have little or no ability to modify the child’s given traits.

If concerns about genetic interventions are ex­plained in terms of parents’ attitudes and children’s self-understanding, then plainly there is no sharp line demarcating genetic from environmental interven­tions. To the degree that an environmental change leaves a permanent reminder of the parents’ own in­tentions for the child (consider surgery to Western­ize the eyes of an Asian child adopted by Western parents), it ought to generate both Habermas’s and Sandel’s concerns every bit as much as it would if ac­complished through genetic intervention. The genes are not special repositories of value. The point is rath­er that the relationship in which we stand to human nature(s), and to the natures of our children, is a mat­ter of human value.


Moral views about human nature, even if widely shared, might not be the kind of thing we think suit­able for legal enforcement. Perhaps the moral attitude toward human nature is a kind of ideal one holds for the relationship between humans and nature. It might be similar in ways to some ideals we have for relation­ships between humans, such as that a person tends to treat others with warmth or generosity. Such an ideal would not issue in blunt pronouncements that some­thing is right or wrong, permissible or impermissible. For a person who holds it, it would be action-guiding, and that person might think better of other people who demonstrate it—indeed, we might still think it an important feature of the moral life—but at the same time, we would not expect everybody to have it, and we would stop well short of thinking that people who lack it are to that degree immoral. They just do not live up to a standard we set for ourselves.

Perhaps, too, this gives one final reason that one need not have a full theory of human nature to have moral qualms about altering it. If a liberty-restricting government policy on, say, research into human clon­ing rests on claims about human nature, then the re­quirement that those claims be publicly accessible and assessable raises the bar for whatever we might claim about human nature. A publicly enforceable moral standard would require a convergence of opinion about human nature, a collective weighing and sifting. A personal moral standard can be based on one’s own considered assessments, and perhaps even on one’s own best guesses.


Gregory E. Kaebnick is research scholar at The Hastings Center and editor of the Hastings Center Report. This essay is drawn from a longer study entitled “Human Nature without Theory,” in The Ideal of Nature: Debates about Biotechnology and the Environment, ed. Gregory Kaebnick (Baltimore, MD: Johns Hopkins University Press, 2011), pp. 49-70.


[1]. L.R. Kass, Life, Liberty and the Defense of Dignity (San Francisco, CA: Encounter Books, 2004), 296.
[2]. Ibid., 85.
[3]. President’s Council on Bioethics, Beyond Therapy: Biotechnology and the Pursuit of Happiness (Washington, DC: President’s Council on Bioethics, 2003), 289.
[4]. Kass, Life, Liberty, and the Defense of Dignity, 288, 294.
[5]. Ibid., 296. Kass emphasizes the importance of mysteries here.
[6]. F. Fukuyama, Our Posthuman Future: Consequences of the Biotechnology Revolution (New York: Farrar, Straus & Giroux, 2002), 130.
[7]. Fukuyama, Our Posthuman Future, 171.
[8]. Ibid., 172.
[9]. Cf. N. Agar, Liberal Eugenics: In Defence of Human Enhancement (Oxford, U.K.: Blackwell, 2004).
[10]. P. Lauritzen, “Stem Cells, Biotechnology, and Human Rights: Implications for a Posthuman Future,“
Hastings Center Report 35, no. 2 (2005): 25­33.
[11]. M. Sandel, The Case against Perfection: Ethics in the Age of Genetic Engineering (Cambridge, MA: Belknap Press of Harvard University Press, 2007), 85.
[12]. Ibid., 82­83.
[13]. J. Habermas, The Future of Human Nature (Cambridge, U.K.: Polity Press, in association with Blackwell, 2003), 8­41.
[14]. Ibid., 57.
[15]. Ibid., 63, 58.
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