HUMAN NATURE

Theories of human nature offer systematic and comprehensive accounts of human beings' most significant distinguishing characteristics. Such accounts are central in people's perennial attempts to organize their understandings of the cosmos; to figure out their relation to God, to nature, and to each other; and to uncover the possibilities, meanings, and purposes of human life.

Western Understanding of Human Nature

Modern Western theories of human nature, which will be the focus of this essay, typically differ from their classical and medieval predecessors in appealing to the findings of a variety of life and social sciences, including anthropology, medicine, physiology, psychology, economics, sociology, and even ethology. Nevertheless, although these sciences undeniably help us to understand specific aspects of human life, even contemporary theories of human nature are never simply summaries of the results of empirical research—despite their frequent claims to scientific authority.

One reason that theories of human nature are not simply generalizations from the conclusions of scientific study is that they enter into empirical investigations not only as conclusions but also as presuppositions, structuring the conceptual frameworks within which research programs are conducted. Contemporary psychological investigation, for instance, proceeds with a variety of models of the human mind, including the Freudian, the behaviorist, the existentialist or humanist, and the computer models. Empirical research cannot fully evaluate the adequacy of its own framework relative to others; determining the adequacy of an entire framework requires reference to considerations beyond empirical data, including how the framework coheres with other respected theories and even its moral and political implications.

A related reason that theories of human nature go beyond ordinary scientific claims is that typically they aspire to provide a comprehensive conceptual framework that will render coherent the contributions of all those disciplines and discourses that investigate various aspects of human life. These often represent human beings in ways that, at least on the surface, appear quite incompatible with each other; for instance, lawyers assume that people ordinarily are responsible for their actions, while psychologists may suggest that people's behavior is determined ultimately by factors outside their control. Theories of human nature endeavor to resolve these incompatibilities in a variety of ways, ranging from reinterpreting the meaning of a discourse, such as the religious, to setting limits on the domain within which its claims are accepted; occasionally, a theory of human nature may even proclaim the invalidity of a whole realm of discourse, such as the parapsychological. Rather than simply summarizing the conclusions of the various life and social sciences, therefore, theories of human nature typically perform a regulatory function, authorizing some methodological approaches while delegitimating others.

Yet another respect in which theories of human nature differ from scientific theories, at least as science is ordinarily understood, is in the prominence of their normative or evaluative component. Even if one contends that all knowledge is to some degree value-laden, the evaluative element is far more evident in theories of human nature than it is, for instance, in modern theories of the physical universe. All theories of human nature provide a general account of human capacities and human needs, human potentialities and human well-being, and thus contain at least an implicit, and often an explicit, diagnosis of human malaise and a prescription for human flourishing.

Like all theoretical constructions, theories of human nature are developed in specific historical circumstances and are designed to address specific conceptual puzzles or practical concerns; consequently, they shift their emphasis according to the scientific, moral, and political preoccupations of the time. Despite variations in focus and emphasis, however, the Western project of understanding human nature historically has centered on two questions. The first of these addresses the human aspect of human nature: How can human be distinguished from nonhuman nature? The second addresses the natural aspect: How can what is natural for humans be distinguished from what is unnatural, abnormal, or artificial? The concerns inherent in these two questions constitute continuing themes that link the variety of Western inquiries into the nature of human beings.

Reflection on these themes reveals that the Western project of providing a systematic theory of human nature has been predicated historically on certain assumptions. They include the following: (1) that it is possible to discover specific qualities or features that characterize human beings universally and transhistorically; (2) that these characteristics decisively distinguish humans from all other beings, notably nonhuman animals; and (3) that, from the discovery of these characteristics, it is possible to derive specific prescriptions about the proper conduct of human life. In other words, the Western project of understanding human nature generally has been motivated by a desire to derive from it universal and unchanging values.

These assumptions went unquestioned and often unarticulated throughout most of Western history. Once they are made explicit, however, it is easy to see that they are all contestable; and we shall see how, in the nineteenth and twentieth centuries, each of them was contested. For instance, Karl Marx (1818–1883) and John Dewey (1859–1952) challenged the first assumption; Charles Darwin (1809–1882) and the twentieth-century sociobiologists challenged the second; and the theorists of positivism and neopositivism challenged the third.

Since the 1970s not only these assumptions but the whole project of developing a comprehensive theory of human nature has been subjected to more fundamental critiques, launched by poststructuralist or postmodern French writers such as Michel Foucault (1926–1984), Jacques Derrida (1930–), and Jean-François Lyotard (1924–). While these authors differ on many points, they are united in rejecting the possibility of any overarching philosophical framework capable of unifying and legitimating the specific disciplines. Such totalizing frameworks or discourses, they claim, reflect unrealizable aspirations to discover universal and absolute truths in morals, politics, or science. These authors deny that any genuinely universal truths can be found, and assert that claims to them typically are propounded by groups who wish to use them for promoting their own political agendas. Truth, they argue, is relative to specific discursive practices that are historically contingent and self-justifying. Consequently, there is no need for, as well as no possibility of, a master discourse designed to be the ground or foundation of these more specific discourses.

As described so far, the dominant tendency in Western thought has been to conceptualize human nature as both universal and transhistorical. Its conceptualizations typically take the form "All human beings throughout history have characteristics x, y, z," implying that x, y, and z are necessary, as well as universal, characteristics of human nature. However, the Western tradition also includes conceptions of human nature that are not universalistic although they are transhistorical. These relational theories take the form "Group x is inferior to group y with respect to characteristics x, y, z"; typically, relational theories are used to justify the dominance of one group over another. Finally, some Western conceptions of human nature are historical rather than transhistorical, used within theories that claim that as human cultures change, so do certain important human characteristics. Some theories contain elements both universal and relational—for example, the theories of Aristotle and the sociobiologists—or both transhistorical and historical—for example, the theories of Karl Marx and John Dewey.

Three Classic Western Approaches

ARISTOTLE. The origins of Western philosophy, in the sense of systematic and rational inquiries into the nature of reality, knowledge, and value, are often traced to the reflections of ancient Greek thinkers in the fifth and fourth centuries b.c.e. Plato (ca. 428–347) and Aristotle (384–322), two of the three philosophical giants of this period (the third being Socrates, ca. 470–399), developed systematic theories of human nature. Aristotle's view has been particularly influential on the Western tradition because it was incorporated into the Scholastic philosophy that dominated Europe in the Middle Ages and early Renaissance, and continues to shape the thinking of the Roman Catholic Church.

Aristotle conceptualized human beings as complexes of soul and body. The soul was the distinctively human element—the essence or form or intelligible principle of the body—but it existed only in conjunction with a living human body. Aristotle's conceptualization of the soul as inseparable from its body contrasted with Plato's view that human beings were souls united only temporarily with bodies, but Aristotle also acknowledged the possibility of the actively knowing and thinking part of the soul, the mind or intellect, being "set free from its present conditions … immortal and eternal." When this happened, however, Aristotle asserted that the mind remembered nothing of its former embodied activity and, because all connection with a specific human body was thus lost, he did not regard the human soul as personally or individually immortal.

Aristotle's view of human nature, like Plato's, was teleological, which is to say that he regarded human beings, like other things in the world, as having a "function" or activity peculiar to them. He further assumed, again like Plato, that the good life, or eudaimonia, consisted in the successful or efficient performance of that function. For Aristotle, the distinctive function of human beings was reasoning, or "an active life of that which possesses reason," and so he inferred that the good life was one in which the rational part of the soul governed the appetitive or desiring part, thus avoiding excess and living in accordance with virtue.

For Aristotle, human beings were, by nature, political animals who needed to live in a community: "He who is unable to live in society, or who has no need of it because he is sufficient to himself, must be either a beast or a god." Within human communities, however, not everyone was capable of citizenship: The nature of some was to rule and of others to be ruled. Among those whose nature was to be ruled were children, barbarians, and Greek women; thus, while Aristotle posited a universal standard for human nature, he simultaneously asserted that some groups of humans were less than fully human. The theme of dominance and subordination runs not only through Aristotle's account of the relations between human beings but even through his account of the nature of individual humans. He compared the controlling relation between form and matter with the relation between male and female, and he asserted that the proper relation between mind and body was like that of master to slave.

AQUINAS. The dominant philosophical figure of the Middle Ages was Thomas Aquinas (1226–1274), later Saint Thomas, who synthesized Greek thought and church doctrine into a Christian philosophy. He conceptualized human nature in terms that were basically Aristotelian, with some (often Platonic) modifications made in order to adapt Aristotelian views to church doctrine.

Aquinas believed, like Aristotle, that there was a distinctive and essential human nature that could be understood teleologically; he also shared the Aristotelian belief that the good life or eudaimonia was action in accordance with this function. A proper understanding of the ends or purposes of human life was therefore essential to morality and should be achieved by discovering the precepts of natural law. Natural law, as Aquinas conceptualized it, was universal and unchanging. It described supposedly universal human tendencies, such as preserving life, but presented them not simply as empirical facts about human nature but also as manifestations of God's design for humanity. For Aquinas, therefore, natural law simultaneously described how things were and prescribed how they should be. It was discoverable by reason, which, because it gave insight into God's purposes, provided guidance on how humans should live.

Like Aristotle, Aquinas saw humans as combinations of soul and body, with the soul as the form of the body. To allow for the possibility of personal or individual immortality, however, Aquinas diverged from Aristotle, declaring that the soul was a "substantial" form, capable of existing separately from matter. Not only was personal immortality conceptually possible, according to Aquinas; it was humans' destiny. God would not have implanted the universal—and therefore natural—human desire to live forever unless this desire had an object.

While Aquinas shared the Aristotelian view that human nature had an end or purpose, he believed, in accordance with church doctrine, that this end was supernatural rather than natural: It was to spend eternity united with God in heaven, where alone perfect happiness might be enjoyed. Human life as we know it was no more than a preparation for life after death, and this world was simply a testing ground for the next. So long as humans inhabited this world, however, they should strive to live in accordance with natural law, which provided a test for the moral validity of the laws of the state.

DESCARTES. The thought of René Descartes (1596–1650) is generally considered to mark the beginning of modern philosophy. Refusing to accept the authority of tradition, Descartes developed "rules for the direction of the understanding" and a "method for rightly conducting reason" designed to enable each individual to establish certain truth in science and philosophy. He wrote in the vernacular (French) as well as in Latin, in order to reach lay as well as clerical readers.

Descartes's conception of human nature was even more dualistic than that of Aristotle and Aquinas. Living human beings, for Descartes, were composed of two entirely different kinds of entities: souls, which were active, intellectual substances, immaterial and immortal; and bodies, which were unthinking, passive mechanisms, spatially extended and temporally finite. Individual humans were to be identified not with their bodies but with their souls, which were able to survive the death of the body. While Descartes's model allowed for the soul's separation from the body after death, it rendered problematic the relation of the soul to the body during life, since it was unclear how material and immaterial substances could have a causal influence on each other. Descartes never succeeded in providing a satisfactory explanation of mind-body interaction.

As a scientist, Descartes wanted his theory of human nature to be compatible with both the new developments in physical science and the doctrines of the Roman Catholic Church. He attempted to reconcile these two worldviews by postulating two spheres of reality, each governed by entirely different laws or principles. The laws of God governed spiritual or mental reality; the laws of science governed physical reality, understood by Descartes in mechanical terms. Although Descartes never developed a systematic moral philosophy, his assertion that all "men" were potentially equal in their capacity to reason laid the foundation for later egalitarian moves in ethics and politics. Simultaneously, his conceptualization of animals as mere stimulusresponse mechanisms, lacking consciousness because they lacked souls, justified the exclusion of animals from moral consideration. Cartesian biologists, in defense of vivisection, have compared the howls of cut-up dogs to the squeaks of unlubricated machines.

SHARED FEATURES OF DOMINANT PRE-DARWINIAN CONCEPTIONS OF HUMAN NATURE. There are at least six common features of pre-Darwinian conceptions of human nature:

1. Human nature is the same transhistorically.
2. It is distinguished primarily by possession of a soul.
3. Human souls are characterized by their capacity to reason. This capacity exists, perhaps in varying degrees, as a potential innate in all humans, sharply distinguishing them from all other beings, including animals.
4. Humans' possession of a rational soul gives them special moral worth.
5. Lacking such a soul, animals lack comparable moral worth or value. Those biological features that are similar in humans and animals comprise humans'"lower" nature, which humans should strive to rise above.
6. Developing our potential to reason is a key to the good life for humans. Reasoning not only tells us how to live well but actualizes our distinctively human potential. Thus, the concept of human nature is clearly normative: Our task is to realize our humanness by fulfilling our potential for rationality; those who are incapable of fulfilling this potential are less than human.

The Materialist Tradition and the Darwinian Pivot

The features listed above as characterizing pre-Darwinian conceptions of human nature represent the dominant Western tradition prior to the nineteenth century. Running counter to this rationalist and dualist tradition, however, Western thought also includes a less prominent materialist or naturalist tradition.

Anaximander (ca. 500 b.c.e.), an early pre-Socratic philosopher, developed a speculative theory of evolution in which human beings were descended from lower forms of animal life. Democritus (460–370 b.c.e.), a contemporary of Socrates, developed a speculative atomic theory in which even the human soul was composed of atoms. The English philosopher Thomas Hobbes (1588–1679) assimilated individual behavior and politics to the laws of mechanics, regarding desire as motion toward an object, and human beings as motivated entirely by self-interest. The French philosopher Julien de La Mettrie (1709–1751) accepted Descartes's assertion that animals were like machines but insisted that so, too, were human beings. The German philosopher Baron Paul Henri d'Holbach (1723–1789) argued that thinking could be reduced to the functioning of the brain and explicitly denied the existence of a soul. Another of the French philosophes, Claude-Adrien Helvétius (1715–1771), argued that all mental faculties were ultimately reducible to physical sensation and that all humans were motivated by the desire to achieve physical pleasure and reduce pain. This latter idea was developed into an elaborate ethical calculus by the nineteenth-century British utilitarians, Jeremy Bentham (1748–1832), James Mill (1773–1836), and the latter's more famous son, John Stuart Mill (1806–1873). Collectively, these philosophers suggested an alternative understanding of human nature—one that focused more on the body than on the soul, on the emotions and desires more than on reason, and on the similarities rather than the differences between humans and animals. It remained for Charles Darwin to give this materialist tradition a scientific basis by providing a naturalistic analysis of the relations between humans and animals.

In his landmark work, On the Origin of Species (1859), Darwin argued that the distinctive features of human nature were not divinely created in an instant but had evolved over many millennia through a process he called "natural selection". Although the word selection suggested conscious purpose, Darwin's use of it was metaphorical, since nature selects only in the sense that certain new traits or mutations that appear accidentally are sufficiently adaptive to the environmental conditions within which the organism lives for the new organism to survive. The view that human beings had evolved through accidental mutations implied that there was no preordained nature, no ultimate meaning or cosmic purpose for human life to fulfill. In an attempt to escape this conclusion and reconcile science with Christianity, some later theorists postulated a direction and a goal in evolution, characterizing more recently evolved species as higher or otherwise superior; but such teleological and evaluative interpretations were ultimately alien to the basically antiteleological spirit of the concept of natural selection.

When Darwin first proposed his theory of evolution, the wife of the canon of Worcester Cathedral was said to have remarked, "Descended from the apes! My dear, we will hope it is not true. But if it is, let us pray that it may not become generally known." Indeed, the church denounced Darwin, recognizing that his theories challenged not only the beliefs in divine creation and a radical discontinuity between humans and animals but also the idea of an immortal soul with special moral worth. Darwin argued that morality had developed from the social instincts of animals; and he construed the uniquely human capacity for rationality, which Aristotle had seen as the telos of human existence, as the outcome of natural selection operating on accidental mutations.

Biological Determinism: A Critique

Once Darwin had demonstrated an evolutionary continuity between humans and other animals, questions arose about the causal role of human biology in relation to other aspects of human life. For many scientists, the project became the reductionist one of showing how the various psychological and social characteristics of human beings were causally determined by human biology.

Many biological determinist theories have negative social implications because they present human characteristics like aggression and dominance as biologically determined and therefore inescapable. For instance, Sigmund Freud (1856–1939), the founder of psychoanalysis, insisted that all human motivation could be reduced to two basic drives—the sexual drive, or libido; and the aggressive drive, an ineradicable instinct to hurt, torture, or kill other human beings (Freud). The German ethologist Konrad Lorenz (1903–1989) also posited an aggressive instinct in humans similar to that he found in his study of various animal species in their natural habitats. In each species, the instinct had evolved to serve one or more life-preserving functions, such as territorial dispersion, selection of the strongest for reproduction, defense of the young, and the establishment of a hierarchy that could provide the group with social cohesion. In species armed with sharp teeth, claws, or beaks, the aggressive instinct was generally coupled with an inhibitory mechanism preventing fighting animals from killing each other; Lorenz argued that there had been no need for such an inhibitory mechanism to evolve in humans because they were not naturally armed. With the development of weaponry, however, the absence of such a mechanism was often lethal, and the advent of nuclear weapons made it a threat to the survival of the species (Lorenz).

More recent studies of animal behavior have generated a new form of biological determinism called sociobiology. Two precursors of sociobiology, anthropologists Lionel Tiger (1937–) and Robin Fox (1913–1971), proposed the concept of a "biogram," a code or program genetically "wired" into the brain that produced certain forms of social behavior, including patterns of dominance and submission—hierarchy among males and dominance of males over females. Both of these were assumed to be the evolutionary heritage of the hunting life of early hominids (Tiger and Fox). The same general line of thinking was employed by entomologist Edward O. Wilson (1929–), who first coined the term sociobiology. Wilson insisted that "genes hold culture on a leash" and play a significant role in determining such human social behavior as altruism toward kin, communal aggression, nationalism, racism, homosexuality, and the dominance of males over females. Wilson has conceded that these biologically based tendencies might be counteracted through extreme social measures, but he argues that humans would pay a high price for doing so (1977).

While Wilson's assertion of a universal genetic tendency toward ethnocentric and racist attitudes was not an attempt to justify racism, there is a long Western tradition of using evolutionary theory to denigrate certain racial or ethnic groups. In the nineteenth century, some scientists in this tradition asserted that Caucasians and Orientals had crossed the Homo sapiens threshold before "Negroes," or that Homo sapiens had begun in Asia and migrated to Africa, where the original stock had degenerated. Others sought to prove racial, ethnic, and class inequalities in intelligence through the use of IQ (intelligence quotient) theory. Frances Galton (1822–1911), a cousin of Darwin who coined the term eugenics, attempted to show that the upper classes had superior intellectual capacities and that blacks were "two grades" below whites. Many of the early IQ theorists in the United States made similar claims about various immigrant groups.

After World War II, when the Nazis had shown the possible social consequences of eugenic ideas, such theories fell into disrepute. They were revived in 1969 when educational psychologist Arthur Jensen (1923–) published an article in the Harvard Educational Review arguing as follows: Intelligence testing has demonstrated that whites score on average about fifteen IQ points above blacks; IQ is 80 percent heritable; therefore, the mean difference between the scores proves a hereditary difference in innate intelligence between the two groups (Jensen). Shortly after Jensen's article appeared, Harvard psychologist Richard Herrnstein (1930–) made a similar argument concerning the difference in IQ scores between upper-class and lower-class people. He concluded that humans should give up any aspirations to democratic equality and accept the idea of a natural meritocracy (Herrnstein).

Biological determinist theories were highly controversial in the late 1960s and 1970s, but in the 1980s and 1990s they became increasingly fashionable—claiming, for instance, genetic factors in alcoholism; locating homosexuality in the structure of the brain; and asserting that men with XYY chromosomes have a tendency toward criminal violence. However, biological determinist theories of human nature are problematic in a number of respects.

Empirically, the evidence for such theories is at best inconclusive. Even within the psychoanalytic tradition, some theorists have argued against Freud that aggressive desires may be explained as derivative manifestations rather than primary instincts, resulting from situations that frustrate other, nonaggressive desires. Ethologists and sociobiologists typically move incautiously from observations of certain animal species or conjectures about early hominids to claims about modern human beings. Sometimes, like Lorenz, they focus on the behavior of fish, birds, and other animals considerably removed from humans—while they ignore studies indicating that many higher mammals, especially primates, display almost no hierarchical organization or intraspecies aggression, being instead peaceful and cooperative. Finally, regardless of how nonhuman species behave, similarities in behavior between humans and nonhuman animals do not establish that the human behavior in question is biologically determined; it may still be a learned response.

Claims for the universality of human aggression, hierarchy, and male dominance also are not confirmed by anthropological evidence. Many hunter-gatherer societies are reported to be remarkably lacking in aggressive behavior, and some enjoy an exceptionally high degree of social equality. Assertions of women's natural dependence on men are undermined by evidence that gathering, a task often performed predominantly by women, is a more reliable food source than hunting in many hunter-gatherer societies. The sexual division of labor varies widely cross-culturally, and even where certain constants are observed, such as a tendency for women rather than men to care for young children, this may be a social adaptation to prevailing conditions rather than a biological predetermination.

Claims about the genetic basis of racial and ethnic differences in IQ are equally suspect. The idea of different evolutionary paths for different races is contradicted by the paleontological evidence; indeed, the concept of race itself is now widely discredited, with anthropologists preferring instead to talk about the statistical frequency of certain characteristics within a geographical population. Further, the idea that IQ tests measure innate intelligence is undermined by the recognition that all tests are culturally biased, since they all require prior learning, and that learning experience can significantly raise IQ. Finally, the very concept of heritability is a technical one, designating a ratio of the contribution of heredity to environment within a given population; it cannot be used, therefore, to compare one population against another.

Biological determinist theories of human nature are not just empirically unconfirmed; they also fail to acknowledge what is most distinctive of our species. The human genetic constitution determines highly developed learning and cognitive capacities that allow humans to respond flexibly rather than instinctively to environmental problems, as well as to develop a range of distinctively human cultural characteristics. The implications of this were noted by one of the world's foremost geneticists, Theodosius Dobzhansky (1900–1975), who wrote, "In a sense, human genes have surrendered their primacy in human evolution to an entirely new, nonbiological or superorganic agent, culture. However, it should not be forgotten that human culture is not possible without human genes" (p. 113). In short, what has developed in the human evolutionary process is a primate with a genetic structure capable of a new kind of evolution, cultural evolution.

Biological determinist theories of human nature contrast sharply in content with their pre-Darwinian counterparts, but they are often inspired by the same motivation of discovering universal and unchanging social values. Typically, they describe as natural aspects of behavior thought to be biologically determined; though few would assert that natural behavior is always to be encouraged or even permitted, characterizing some behavioral tendencies as natural provides a certain legitimation for them. Because they are understood as resulting from natural selection, such tendencies are regarded as having been necessary at least at some time for human survival; in consequence, they cannot be entirely deplored, and they may even be romanticized as clues to a more natural way of life. Thus, biological determinist approaches to understanding and evaluating human nature may be seen as secular analogues of Aquinas's theory of natural law.

It may be the social function of biological determinist theories of human nature, rather than their scientific credentials, that accounts for their continuing popularity. Put simply, these theories tend to rationalize existing manifestations of aggression and inequality: Biological determinist analyses of violence, war, and crime tend to deflect attention from the social and economic causes of these phenomena, just as theories about the biological determinants of male and female behavior distract us from the ways in which men and women are socialized for their respective roles. The implication often drawn from biological determinist theories is that significant social movement in the direction of peaceful cooperation and equality is impossible because it is alleged to go against human nature. Clearly, those in power benefit from such an assumption and are likely to encourage the development of such theories.

Behaviorism: Another Form of Post-Darwinian Reductionism

The Western materialist or naturalist tradition has not always moved in a biological determinist direction. It also includes thinkers who claim that environmental or cultural factors are the primary determinants of the human mind or behavior. The philosopher John Locke (1632–1704) saw the human mind as a kind of blank tablet to be written upon by sensory impressions, while Enlightenment figures like Helvétius assumed that education could shape human beings into almost any form.

In the first part of the twentieth century, environmentalist ideas became popular in the United States through a psychological movement known as behaviorism. John B. Watson (1878–1958), who first systematically developed the theory, insisted that in order for psychology to become a rigorous experimental science, it must give up its introspective orientation. It should no longer take its task to be analyzing private mental states, such as feelings, desires, and thoughts, but instead should study the relation between publicly observable behavior and the environment. For Watson, the two basic forms of this relation were the unconditioned and the conditioned reflex. The former was the basic human physiological endowment, consisting of automatic responses to environmental stimuli, such as salivating in the presence of food and contracting pupils in the presence of light. Watson based his analysis of the conditioned reflex on the work of the Russian experimental psychologist Ivan Petrovich Pavlov (1849–1936), who had demonstrated that a hungry dog, repeatedly presented with both food and the ringing of a bell, would eventually salivate at only the bell-ringing. The sound of the bell had become a substitute stimulus, and the salivation was now a conditioned response. For Watson, all human behavior could be reduced to these two kinds of reflexes.

Watson's version of behaviorism was superseded by that of B. F. Skinner (1904–1990), who argued that reflex action could account for only a small part of human behavior. For Skinner, human behavior was primarily shaped by what he called operant conditioning, which reinforced certain spontaneous movements of the organism. For example, when a pigeon raised its head above a certain height and food was released into its cage, the result was a higher frequency of that behavior. Unlike the stimulus in Watson's model, the "reinforcer" (the food) was introduced after the "response" (the raising of the head to the desired height) occurred. For Skinner, most human behavior other than automatic reflex action, even human language, could be explained as the result of positive or negative reinforcement, which, by adding something to the situation (food, sex, money, praise, etc.)—or by removing something from it—increased the frequency of some behavior. While not denying that feelings and thoughts existed, Skinner refused to characterize them as residing in a special mental domain, consciousness, and claimed that they had no causal effect on human behavior (Skinner, 1953).

Both Watson and Skinner believed that human beings could be conditioned to develop almost any pattern of behavioral responses. Watson boldly declared that he could take almost any infant "at random and train him to become … doctor, lawyer, artist, merchant-chief, and, yes, even a beggar man and thief." Skinner insisted that operant conditioning "shapes behavior as a sculptor shapes a lump of clay." One evident consequence of the behaviorist program was that human freedom was an illusion. For Skinner, in particular, such concepts as freedom, moral responsibility, and human dignity were the conceits of a prescientific age (Skinner, 1973).

Behaviorism, just as much as biological determinism, is heir to the evolutionary paradigm because human behavior is still explained in terms of genetic dispositions regarded as having survival value. For behaviorism, however, these predispositions are not instincts or drives. Instead, specific unconditioned reflexes have evolved in the human species because they have survival value, while the human organism's susceptibility to conditioning helps it survive by allowing it to adapt to environmental changes more rapidly than its genetic structure could.

There are a number of difficulties with the behaviorist conception of human nature. First are the primary data of consciousness, such as desires, feelings, reflection, and decision making; it is hard to believe that these do not have at least some causal influence on human activity. Second, the fact that pigeons, rats, and human beings can sometimes be controlled by operant conditioning does not mean that all human behavior can be understood in this way. Linguist Noam Chomsky (1928–), for example, has argued against Skinner that linguistic competence requires creativity that goes beyond responses to prior conditioning because we are constantly constructing sentences that we have never before encountered. Finally, there is no room in the behaviorist model for human agency: The environment acts, human beings merely react. In this, behaviorism may be seen as ideologically reflecting a world in which people are continually managed and manipulated by technocratic and bureaucratic elites.

Social and Historical Conceptions of Human Nature

Social and historical conceptions of human nature offer an alternative to seeing human beings either as primarily determined by their biological drives or as passive clay to be molded by their physical and social environment. These approaches, while not ignoring human biology or the role of social conditioning, emphasize the importance of human social activity within specific historical contexts. The work of the revolutionary social theorist Karl Marx, together with his collaborator Friedrich Engels (1820–1895), and of the U.S. pragmatist philosopher John Dewey, provides two examples of this approach.

Marx and Engels's view of human nature (Schmitt) was embedded in their more general theory of human history, historical materialism. Human history, they contended, began with humans' attempt to satisfy their basic biological needs through producing their means of subsistence, so that human beings were, first and foremost, producers. Human production differed from that of nonhuman animals in that it was deliberate rather than instinctive, involving imagination, planning, and tool use. It was also inherently social, not only in requiring the coordination of human effort but also in utilizing skills and knowledge transmitted from one individual, group, or generation to another. In societies producing a surplus beyond that needed for immediate survival, human production typically involved a division of labor going beyond a division into separate tasks, to a division between intellectual and physical work and between work considered appropriate for men and for women. Most important for Marx and Engels was the class division of labor between those groups who owned the means of production and those who had to work for them, a division generating the class struggles regarded by Marx and Engels as the motor force in history.

Different economic systems, or what Marx and Engels called modes of production, established forms of social life through which human beings individuated and understood themselves. Peasants and artisans, ladies and gentlemen, merchants and professionals, corporate capitalists and industrial workers would tend to think and act differently from each other. Changes in the mode of production would generate new forms of social life, new ways of understanding the world, and new ways of thinking and acting—in effect, new kinds of individuals. Thus, human nature itself would change. Since human beings were active in the class struggle that caused these social and economic changes, however, it could also be said that human beings actively changed their own natures over the course of history.

For John Dewey, as for Marx and Engels, human beings were neither governed by instincts nor passive recipients of environmental forces; rather, they were social agents who changed their own natures in the process of changing their societal conditions. However, in contrast to Marx and Engels, Dewey regarded the motor force of social change not as class struggle but as the product of reflective intelligence.

Dewey acknowledged that human beings had instincts—or impulses, as he preferred to call them in order to discourage associations of inflexibility. Impulses, in his view, were extremely flexible in that they could take on a variety of meanings, depending on the social context. Thus, the impulse of fear might become cowardice, caution, reverence, or respect; while the impulse of anger might become rage, sullenness, annoyance, or indignation. Impulses took on these meanings as habits, predispositions to certain kinds of thinking and acting, ultimately embodied in social customs and institutions. The content of these habits constituted our historical nature. However, when the habits proved inadequate to new social problems, humans could employ their reflective intelligence to redirect their impulses into new habits. For example, as war became increasingly problematic or as certain economic institutions become increasingly outmoded, human impulses could be rechanneled, creating new institutions embodying new habits.

To make sense of the claim that human nature changes, we need to remember the distinction between transhistorical and historical conceptions of human nature. For both Dewey and Marx, it is precisely because a certain transhistorical human nature exists—socially productive and reflectively intelligent—that the content of human nature can be changed historically. To put this point in a more contemporary idiom: Our distinctively human capacity to transform social institutions transforms social roles and, in so doing, transforms historically specific character structures.

Giving more weight to the social and historical aspects of human nature offers a new model of the relation between genetic determination and social conditioning, on the one hand, and social behavior, on the other. What is determined by our genes is our capacity to learn, reflect, and work for change. Humans can, thus, be agents of their own history. Biology determines certain potentialities, but it is only through concrete historical activities that humans develop certain specific cultural and psychological characteristics. Genes dictate the ability to develop general modes of response, such as learning languages, engaging in productive labor, and developing forms of social relatedness; but they do not dictate that humans learn English, produce nuclear weapons, or become selfish and competitive as opposed to altruistic and cooperative. Thus, historical and social conceptions of human nature do not deny biology but refuse to privilege it as the primary cause of human action. Similarly, they do not deny conditioning but equally refuse to privilege it in explaining human action. Certain social conditions undoubtedly encourage the development of certain habits, but these are not merely behavioral responses; instead, they are social patterns of meaning that connect thought to action. Furthermore, human beings do not merely react to social conditions but individuate themselves within them and can reflect intelligently on them. Thus, both individually and collectively humans can decide to change their habits and work to transform the social conditions from which they arose.

A Social and Historical Conception of the Human Body

Although many theorists are willing to acknowledge that people's character or personality or behavior is socially shaped, at least to some degree, the biological constitution, the body, is often viewed as a presocial given, the universal and unchanging foundation on which elaborate cultural edifices are erected. According to this way of thinking, the body constitutes the most natural aspect of human nature. Itself a product of natural selection, the body sets the natural, that is, biologically determined, limits of social variability.

While it may be true that there is less systematic crosscultural and transhistorical variation in people's bodies than there is in their personalities and social institutions, it is too simple to regard the human body as a presocial given. Although the human body may sometimes be experienced as a given, in fact, like the mind or the personality, bodies are socially and historically shaped on several levels.

It is not difficult to recognize some of the ways in which human bodies are influenced by their social context. Different kinds of work and living conditions develop or distort the body in various ways. For instance, scarcity of food results in stunted growth, so that body size and development vary systematically not only between cultures but often also between social classes. While many of these bodily marks are unintended side effects of social practices, others are deliberately induced. Social norms are consciously inscribed on the body in a variety of ways, ranging from foot-binding and circumcision to diet clinics and cosmetic surgery. The varying social meanings assigned to bodily characteristics and functions influence a person's experience of his or her body, which, depending on the social context, may become a source of pride, joy, pain, or embarrassment.

Social influences on the human body operate not only on the level of observable physical structure, the phenotype; in the past, they have also influenced the genotype, our genetic inheritance, and they continue to do so. While human prehistory is highly speculative, it seems likely that some genetically heritable characteristics have been selected not only naturally, as adaptive to such nonsocial circumstances as climate and food availability; but also socially, as adaptive to certain forms of social organization or perhaps even as the results of conscious social preferences. For instance, the average size difference between human males and females may have been a consequence as much as a cause of male dominance: If the dominant males fed first and most, only smaller-framed women could survive on the leftover food. Even today, the human gene pool continues to be influenced by social factors. For instance, exposure to environmental pollutants sometimes leads to genetic mutations, and modern medicine now makes it possible for people to survive and reproduce with genetic conditions that otherwise would have led to their early deaths. Finally, genetic engineering is rapidly becoming a real possibility.

The recognition that even the genetic constitution is influenced by social factors has far-reaching consequences for understanding human nature. The point is not simply that most versions of biological determinism are false because they fail to give sufficient weight to the social determinants of human characteristics. It is, rather, that the usefulness of the whole nature-culture distinction as an analytical framework for understanding human beings comes into question. Just as we cannot identify any cultural or social phenomena uninfluenced in some way by human biology, neither can we identify any human biological or natural features that are independent of social influence. The biological and the social are so intertwined in the human past and present that it becomes impossible in principle to distinguish the natural from the social or cultural components in the constitution of human beings. As far as human beings are concerned, the relation between nature and culture is mutually constitutive: To oppose one to the other is incomprehensible. Everything that we are and do is revealed as simultaneously cultural and natural.

Ethical Implications for the Life Sciences: A Cautionary Tale

What are the bioethical implications of these various conceptions of human nature? First, a cautionary note. Practical ethics reflects on a host of considerations in practical contexts and cannot simply deduce specific moral conclusions from general ethical principles, let alone from some general conception of human nature. Thus, the relation between the various conceptions of human nature and any specific bioethical position is unlikely to be one of logical entailment. This does not mean, however, that concepts of human nature have no relevance to bioethical issues. They may serve as starting points for bioethical analysis, raise suspicions about certain bioethical claims, or even rule out certain bioethical positions. In general, certain conceptions of human nature may be said to cohere, or provide a better fit, with certain bioethical stances than with others.

The dominant pre-Darwinian conceptions of human nature view physical nature, including the human body, as the realm of the material, the immanent, and the profane, and identify God with the spiritual, the transcendent, and the sacred. It is only because human beings are endowed with a soul that they are regarded as capable of partaking in the sacred, and their mission is to transcend their bodies and realize their spiritual nature. Insofar as they are part of God's creation, nonhuman animals are sometimes assigned a degree of moral worth, but the view that they lack souls typically rationalizes the claim that nonhuman animals are merely resources to serve human purposes. Saint Francis of Assisi notwithstanding, the dominant view of the Judeo-Christian tradition is that God created nonhuman animals and, indeed, all of nonhuman nature, primarily for the use of human beings. This sharp bifurcation between human and nonhuman nature not only permits but even legitimates the human subjugation and exploitation of all nonhuman nature, and may therefore contribute to the contemporary ecological crisis.

Within this ontology, the human body occupies a unique and somewhat ambiguous moral status. Although material, and therefore a source of temptation, the body is nevertheless sacrosanct because it is indispensable to human life. God is thought to have a divine plan for humanity, and any attempt to subvert this plan by tinkering with the human body is regarded as at least prima facie wrong. When applied to humans as opposed to nonhuman animals, therefore, reproductive technology, genetic engineering, and euthanasia are viewed with suspicion, if not censure; and brain death may not be considered sufficient reason to switch off a life-support system, depending on when the soul is believed to leave the body. If, for example, the soul is thought to remain in the body until the last breath of life, then euthanasia can never be justified: Even the suffering and dying body must be revered as the house of the soul. Finally, because humans are morally distinguished by the possession of a soul, abortion is condemned at whatever point the fetus is believed to acquire a soul. It is interesting to note that the Catholic Church has not always held that fetal ensoulment occurs at the moment of conception: Saint Thomas Aquinas, for instance, argued as an Aristotelian that the fetus did not have a soul until it assumed human form, which he thought occurred after three months' gestation for the male fetus and six months' for the female.

In contrast with the pre-Darwinian dichotomies between human and nature, spiritual and material, sacred and profane, post-Darwinian conceptions of human nature posit an evolutionary continuity between human and nonhuman animals. This continuity is sometimes used as a basis for moral challenges to the human exploitation and domination of animals, especially animals that are close to human beings in evolutionary terms. It is precisely those nonhuman animals most like humans, however, that are most useful for many purposes, such as medical experiments and organ transplants; in consequence, some philosophers have sought to undercut moral challenges to the human exploitation of nonhuman animals by arguing that beings lower on the evolutionary scale may be sacrificed for the good of higher species. Opposing this position is a growing minority in the bioethics community that argues that such a position is an example of unwarranted human chauvinism or speciesism, a term invoked to suggest parallels with racism and sexism.

Although post-Darwinian assumptions of an evolutionary continuity between humans and nonanimals may be used to challenge the view that animals are simply a resource for human use, they have also been used to justify radical interventions in human life processes. If it is legitimate to experiment on nonhuman animals, for instance, it may be equally legitimate to experiment on human beings. If Homo sapiens is the accidental outcome of natural selection, if there is no inherent purpose for which we are created, then there is no a priori reason to assume that further modifications in human biological processes should not be made via reproductive technologies or even genetic engineering. Since the human nervous system is a defining component of human life, the fetus at an early stage of brain development is likely to have a different moral status than it does once the brain has developed. Certainly, the post-Darwinian conception of human nature would generally assume that brain dead means dead.

These conclusions reflect the absence of the concept of a soul in post-Darwinian views of human nature, since it was the soul that, in earlier conceptions, provided the philosophical grounding for human dignity. Unless an adequate substitute for the concept of the soul can be found, post-Darwinian conceptions of human nature may permit the drastic manipulation of human beings. Behavior regarded as undesirable may be treated either as a biological abnormality or as a failure of social conditioning. Biological determinists may regard alcoholism, addictive gambling, violent criminal behavior, schizophrenia, depression, and even homosexuality as candidates for treatment with a variety of biological techniques: psychosurgery, shock therapy, hormonal therapy, psychopharmacological interventions, and perhaps, in the future, even genetic manipulation. Behaviorists, of course, emphasize the use of various conditioning techniques to modify human behavior, raising the prospect of a Clockwork Orange world. Skinner, in fact, wrote a utopian novel, Walden Two (1948), in which behavioral managers conditioned people from birth to make choices in accord with the goals and institutions of that society. Both biological and behavioral interventions often work toward the same goal—direct control of human behavior.

But who will control the controllers, and how far will such control be allowed to extend? There are already biological determinists who advocate the use of genetic manipulation to raise IQ or to alter certain undesirable tendencies in the human species, perhaps to create a Superman. Others would clone the embryo and store it for future use, perhaps in case of some failure of the original stock. Brave New World may be just around the corner unless we can reclaim the concept of human dignity. Social and historical conceptions of human nature offer a secular basis for doing so.

Although people who accept a social and historical conception of human nature may still utilize some concept of naturalness in describing various human activities, such as conceiving or giving birth, they recognize that what is taken to be natural or unnatural changes historically and culturally, so that ethical decisions cannot be grounded in some unchangeable concept of human nature. However, this does not prevent us from ethically evaluating various attempts to manipulate and control human nature. Indeed, those who accept social and historical conceptions of human nature are likely to urge caution in the use of biological interventions and conditioning techniques for the purposes of altering human behavior. They will be suspicious of all treatment and research modalities that fail to respect human agency, reflective intelligence, and decision-making capabilities, since it is precisely these transhistorical capacities that make possible the continuous transformation of our historical natures. In short, social and historical conceptions of human nature will tend to reaffirm the concept of human dignity. In the sphere of medicine, for instance, they are likely to insist on the dignity of medical subjects and emphasize informed consent and coparticipation in physician-patient relationships.

The recognition that human beings individuate themselves within and through social processes may also have implications for the abortion controversy; at the very least, it suggests that women and fetuses cannot have the same moral status. Moreover, social and historical conceptions of human nature emphasize that consideration of bioethical problems must be sensitive to concrete social and political contexts; in a society with an expressed commitment to human equality, for example, questions like procreative technology or contract parenting must be evaluated with special reference to their implications for people of different classes, genders, abilities, races, and ethnicities. Finally, social and historical conceptions regard human beings as transhistorically creative, productive, social, and capable of reforming their habits through reflective intelligence; and people who accept these conceptions are likely to valorize those capacities and seek to develop social institutions—including healthcare, psychiatric, and research institutions—through which they would be enhanced.

The open-ended nature of these last implications serves as a reminder that ethical conclusions are not strictly entailed by any general conception of human nature, especially by social and historical conceptions. In addressing particular bioethical problems, therefore, the values implicit in these conceptions must be supplemented by explicitly ethical criteria, such as historically specific understandings of justice, freedom, and human well-being.

alison m. jaggar

karsten j. struhl (1995)

bibliography revised

SEE ALSO: Behaviorism; Enhancement Uses of Medical Technology; Eugenics; Freedom and Free Will; Genetics and Human Behavior; Genetics and Human Self-Understanding; Human Dignity; Natural Law; Nanotechnology; Transhumanism and Posthumanism

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HUMAN NATURE

Many ethical judgments make appeals to human nature either as their foundation or as their standard. In the strongest case ethics is argued to be based on human nature; in other instances actions are proscribed if they fail to respect human nature or are recommended because they are said to be in harmony with human nature. Human nature is also an object of scientific investigation, raising questions related to both process and product: whether scientific investigation is undertaken in ways that respect human nature and whether the results of such investigations can contribute to the understanding of human nature in an ethically relevant sense. After a brief review of theories of human nature, the focus in this entry will be on the final question: the extent to which scientific knowledge of human beings can contribute to understanding or assessing these theories, especially in their role as foundations for ethics.

Theories of Human Nature in History

According to Leslie Stevenson (2004), theories of human nature entail theories about the world, human beings, what might be wrong with human beings, and how anything that is wrong might be corrected. Even those who deny any essential human nature in favor of a historical or cultural construction of human nature have views about what kinds of things human beings are and their place in the world. However, with regard to explicit theories of human nature, premodern theories generally viewed humans as properly subordinate to a larger order so that even though people on occasion rebel against that order (by means of what the Greeks calls hubris and the Bible calls sin), they are called upon to learn to control such rebellion by means of ethical or religious practices. By contrast, modern theories tend to see human beings as unjustly limited by the larger order and thus encouraged to overcome those limitations, often by means of science or technology.

More specifically, for Plato, in a famous analogy from the Republic (p. 437b ff.), the human soul is presented as being composed of three parts: appetite, reason, and spiritedness. Lack of order results whenever appetite or spiritedness predominates and steps outside the guidance provided by reason. In a similar manner, for Aristotle in Nicomachean Ethics (vol. I, p. v), human lives can be oriented toward pleasure, politics, or knowledge, but the perfection of human nature resides with rationality in both practice and theory. Thomas Aquinas (1224–1274) further develops this perspective by arguing that the lawful order of nature is manifest in human nature (in a form he terms natural law) in aspirations to life, affective sociability, and the rational pursuit of both politics and science. Although the Jewish, Christian, and Islamic views of human nature seek in some measure to subordinate rationality to faith in revelation, that faith, like reason, ultimately places boundaries on appetitive, political, and even scientific activities. Structurally similar views can be found in the Asian religious and philosophical traditions associated with Hinduism and Buddhism.

More typically modern theories such as those of Thomas Hobbes (1588–1679) and John Locke (1632–1704), even when they offer a materialist and mechanistic analysis of the workings of human nature, argue that humans are improperly constrained by the state of nature. In Hobbes's frequently cited description, the state of nature is one in which human life is "solitary, poor, nasty, brutish, and short" (Leviathan, vol. I, p. 13), a condition from which human beings justly seek any means of escape. This notion that people are unjustly constrained by the human condition is repeated and developed in philosophies as diverse as those of Jean-Jacques Rousseau (1712–1778), Immanuel Kant (1724–1804), Georg Hegel (1770–1831), and Karl Marx (1818–1883). According to Rousseau, for instance, "Man is born free, but everywhere is in chains" (Social Contract, vol. I, p. 1). The psychological theory of Sigmund Freud, with its distinction between id, ego, and superego, reverses Plato's theory by suggesting the primacy of id or appetite over both individual self (ego) and social restraint (superego).

Three Basic Approaches to Human Nature

What can science contribute to the assessment or criticism of these diverse theories of human nature? One scientific debate concerns the relative influences of nature and nurture in human affairs. Another focuses on degrees of rationality or nonrationality in human decision and action. Among the most fundamental questions is that concerning whether there is something—a rational or transrational mind or soul—that cannot be accounted for by the same material causes that govern all other things in the natural world.

Materialism (or physicalism) is the position that the physical world is self-contained or closed so that the physical world can be explained only through physical causes and effects. In considering human nature, a materialist would say that human beings must be explained as purely material mechanisms, as physical bodies governed exclusively by physical causes. Consequently, the human mind should be understood as an activity of the physical brain. All the thinking, feeling, and willing of the conscious self must be determined totally by the body, particularly the brain and nervous system.

Against such a materialist view of human nature a dualist would argue that mind is not fully reducible to body, that the mind can act as an immaterial cause on the material brain. An interactionist dualist would agree that the mind depends on the brain as its necessary but not sufficient condition. Thus, if some part of the brain is damaged or ceases to function normally, this can interfere with mental activity. Still, as long as the mind is supported by normal brain activity, the mind can exert its independent power over the brain. When people act through conscious thinking and willing, they use their immaterial minds to control their material brains. A religious believer might go further and claim that the immaterial mind was created by an immaterial God, and thus the mind or soul is supernatural. This supernatural character of the soul could render it immortal so that the human soul could survive the death of the human body.

There are, then, at least three fundamentally distinct views of human nature that are based on three views of the relationship between mind and body. The materialist believes that the mind has no immaterial power to act on the body. The interactionist believes that the immaterial mind interacts with a material body. The supernaturalist believes that the immaterial mind is supernatural and immortal. Each of these views implies more general perspectives on human beings and their place in nature.

Traditional Arguments for Interactionism

These conflicting views run throughout the history of natural science from Socrates to the present. In Plato's Phaedo (pp. 96a–100a) Socrates (470–399 b.c.e.) talks with his friends while awaiting execution. He recounts that as a young man he thought that a scientific investigation of nature would explain the causes of everything. He hoped to explain the physical causes of all things coming into being and passing away, including the causes of animal life and the causes of human thinking in the brain. He became frustrated when he found that a complete science of nature as governed by physical causes was beyond his grasp. To explain the world, Socrates insists, it is necessary to understand both physical causes and mental causes. For example, to explain why Socrates is sitting here awaiting his execution, one might describe the physical mechanisms in his body—the bones, muscles, ligaments, and so on—that control his movement. However, although these physical causes are necessary in explaining why he is sitting here, they are not sufficient. It is also necessary to explain how Socrates made up his mind to accept his punishment because this mental decision controls his physical body.

Socrates appeals to a person's ordinary experience of making up his or her mind and then freely choosing to act according to that conscious mental decision; this leads people to think that the mind has a power to act that changes the physical causes of the body. Holding oneself and others morally and legally responsible for their conduct assumes that freedom of thought and choice. People do not hold nonhuman animals or human children morally responsible for their behavior because it is assumed that they lack the moral freedom that is attained only by the development of rational choice in normal human adults through learning and habituation. If human conduct were fully determined by physical causes in the body, it would be impossible to hold people morally or legally responsible for their conduct.

From ancient Greece to the present this kind of Socratic thinking has led many scientists, philosophers, and theologians to conclude that human nature is characterized by a complex interaction of mind and body, mental causes and physical causes. The human mind acts upon the human body, or the mind exerts an immaterial power that is not reducible to the material causes of the body.

Modern Arguments for Materialism

Socrates was responding to a materialist or physicalist tendency that would become a strong tradition in Western science. That materialist tradition gained great power during the scientific revolution of the sixteenth and seventeenth centuries. Proponents of the new science saw the universe as a mechanism that could be explained by mechanical laws working through purely physical causes. It seemed that much of human nature could be explained similarly without invoking an immaterial soul.

Hobbes saw nature as matter in motion governed by laws of motion such as those discovered by Galileo (1564–1642). Animal life, then, including human life, is "but a motion of limbs." "For what is the heart, but a spring; and the nerves, but so many strings; and the joints, but so many wheels, giving motion to the whole body" (Leviathan, Introduction). Animal motion is driven mechanically by selfish passions that goad animals to seek pleasure and avoid pain. Although human beings are moved by some of the same selfish passions, humans are unique in their capacity for reason and speech. However, even this uniquely human intellectual activity can be understood mechanistically as the computational manipulation of informational symbols (Leviathan, vol. I, p. 5). The soul or mind cannot be immaterial. It must be the activity of the material body. This must be so if one accepts the claim of natural science that everything in the universe is matter in motion. Because of his materialism Hobbes was denounced by religious and political leaders as a morally corrupting teacher of hedonism, egoism, and atheism.

Hobbes's materialist science of the soul seemed to be confirmed by Thomas Willis's (1621–1675) studies of the brain. Working in England at the same time as Hobbes, Willis compared the anatomy of the human brain with that of other animal brains and combined experiments on brains with medical observations of brain-damaged patients to develop what he called "neurology." He reached five broad conclusions. First, all mental experience arises from the motion of "animal spirits" undergoing chemical changes in the brain. Second, different parts of the brain have different functions. Third, the human brain resembles other animal brains, particularly those of monkeys and apes. Fourth, this science of neurology could be used by medical doctors to cure diseases of the brain through the use of drugs that would alter the chemistry of the brain. Fifth, all this supports the general view of the "mechanical philosophy" of the seventeenth century that the human body and brain are both machines explainable by mechanical laws.

Although Willis was mistaken about many details, his broad conclusions are supported by modern neuroscience. What Willis called animal spirits can be understood as electrical and chemical signaling between neurons. Willis's observation that the brain has specialized functions has been elaborated by studies of the ways neurons are organized into modular networks with distinct functions. Willis's claim that the human brain resembles the brains of other animals can be explained by evolutionary biology. His hope that drugs could cure the diseases of the soul seems to have been fulfilled by modern psychopharmacology in its use of drugs to treat mental disorders and enhance mental function. Finally, Willis's mechanistic account of the mind has been elaborated with computer models of the mind as an information-processing system.

It may appear, then, that the science of the human brain initiated by Willis proves Hobbes's materialist view of the soul. However, Willis was not a strict materialist because he believed that his science showed the existence of two souls. The "sensitive soul" found in all animals was purely material and therefore vulnerable to physical diseases. In contrast, the "rational soul" found only in humans was immaterial and immortal, although it depended on the sensitive soul. Thus, Willis's account of human nature was interactionist in that he thought the material brain and the immaterial soul mutually influence each other. He was also a supernaturalist in that he thought the immaterial soul was created by God to be immortal.

In the early twenty-first century some scientists, such as James Watson (2003), Edward O. Wilson (1998), and Steven Pinker (2002), argue that natural science sustains a purely materialist view of human nature and refutes any belief in the human soul as immaterial or immortal. Those scientists dismiss belief in an immaterial soul as an unscientific superstition. However, other scientists, such as Wilder Penfield (1978) and John Eccles (1994), defend Willis's interactionist view of the mind as an immaterial cause that can act on the brain. Eccles, a Nobel Prize–winning neuroscientist, has argued that modern neuroscience is compatible with belief in the self-conscious mind as an immaterial power for thinking and choosing.

Ethical Implications

What difference do these debates over the science of mind-brain interaction make for an understanding of human nature and morality? Those who argue for an immaterial soul agree with Socrates that the capacity of the mind to act outside the laws of physical nature is necessary for moral freedom. They warn against scientific materialism as a denial of free will that would make it impossible to hold people morally responsible for their conduct. They also warn that a materialistic view of human nature would promote a Hobbesian hedonism in which people would see themselves as animals moved by selfish passions with no spiritual capacity for rising above their material interests. To explain the soul as merely biochemical activity in the brain would seem to deprive human life of any unique moral dignity. Moreover, if scientific materialism teaches that human nature has only limited dignity above the rest of nature and if the ultimate end of modern science is the conquest of nature, people may be tempted to use the technological power of science to alter human nature itself in ways that would be dehumanizing.

The history of eugenics illustrates the potentially corrupting effects of a materialist view of human nature. The Judeo-Christian view of human beings as having been created in God's image with immortal souls has supported the moral principle of the special sanctity of human life. However, by the end of the nineteenth century modern science, particularly Darwinian science, had persuaded many people that human beings are merely highly evolved animals and that they do not have immaterial or supernatural souls that set them above the rest of animal nature.

If human beings are products of an evolutionary process governed by survival of the fittest, it seemed that reproductive fitness would be the only moral value coming from nature. Proponents of eugenics argued that human beings should be bred just as other animals are to improve the genetic quality of the species. As a result many state governments in the United States passed laws that forced individuals regarded as genetically inferior to be sterilized so that they could not reproduce. In Nazi Germany, Adolf Hitler (1889–1945) used policies of eugenics, euthanasia, and genocide to eliminate people whom he identified as belonging to inferior races. Some historians, such as Richard Weikart (2004), have explained the horrors of eugenics and Nazism as having been caused partly by the influence of Darwinian materialism in devaluing human life.

Other philosophers such as Peter Singer (2001) have argued that because religious belief in the sanctity of human life has been refuted by scientific materialism, people may be morally justified in euthanizing infants born with severe deformities. Some posthumanist or transhumanist proponents of biotechnology see no moral limit on the power to use science to redesign human beings, perhaps even to the point of abolishing human nature itself. All this seems to confirm the fears of many people that modern science, insofar as it promotes a materialist view of human nature, subverts traditional morality.

At the same time some scientific reasoning about the human mind may support traditional morality by showing how it is rooted in the brain. In The Descent of Man (1871) Charles Darwin (1809–1882) argued that a natural moral sense was implanted in human nature by evolutionary history. As naturally social animals, human beings evolved to have a natural sense of right and wrong that would support social cooperation on the basis of ties of kinship and reciprocity. To reinforce this cooperative behavior they were endowed with emotional propensities to moral emotions such as love, guilt, and indignation and also were endowed with the intellectual capacity to formulate social norms of cooperation rooted in those moral emotions.

Some neuroscientists have found that moral experience depends on the moral emotions sustained by the emotional control centers of the brain and on the moral reasoning carried out in the prefrontal cortex of the brain. If these parts of the brain are not functioning normally, people cannot act as moral beings. For example, psychopathic criminals apparently have an abnormality in their brain circuitry that prevents them from feeling the moral emotions that support the moral conduct of normal human beings. Such scientific research suggests that morality is part of the biological nature of human beings.

LARRY ARNHART

SEE ALSO Christian Perspectives: Historical Tradition;Dignity;Enlightenment Social Theory;Hobbes, Thomas;Humanization and Dehumanization;Hume, David;Natural Law;Posthumanism.

BIBLIOGRAPHY

Arnhart, Larry. (1998). Darwinian Natural Right: The Biological Ethics of Human Nature. Albany: State University of New York Press.

Barbour, Ian G. (2002). Nature, Human Nature, and God. Minneapolis: Fortress Press. A survey of the ethical and religious issues in the scientific study of human nature.

Damasio, Antonio R. (1994). Descartes' Error: Emotion, Reason, and the Human Brain. New York: Putnam. A seminal work on the emotional basis of ethics in the brain.

Darwin, Charles. (1871). The Descent of Man, and Selection in Relation to Sex, 2 vols. London: J. Murray.

Eccles, John. (1994). How the Self Controls Its Brain. Berlin: Springer-Verlag.

Greene, Joshua D.; R. Brian Sommerville; Leigh E. Nystrom, et al. (2001). "An fMRI Investigation of Emotional Engagement in Moral Judgment." Science 293: 2105–2108. Images of the brain making moral judgments.

Hobbes, Thomas. (1957). The Leviathan, ed. Michael Oakeshott. Oxford: Basil Blackwell.

Penfield, Wilder. (1978). Mystery of the Mind. Princeton, NJ: Princeton University Press.

Pinker, Steven. (2002). The Blank Slate: The Modern Denial of Human Nature. New York: Viking. A vigorous defense of a scientific theory of human nature against the major criticisms.

Plato. (1961). The Collected Dialogues of Plato, ed. Edith Hamilton and Huntington Cairns. Princeton, NJ: Princeton University Press.

Popper, Karl R., and John C. Eccles. (1983). The Self and Its Brain: An Argument for Interactionism. London: Routledge & Kegan Paul. A history of the mind-body problem in philosophy and neuroscience and an argument for the immaterial nature of the mind.

Richards, Janet Radcliffe. (2000). Human Nature after Darwin. London: Routledge. A study of the philosophic implications of Darwinism for human nature.

Singer, Peter. (2001). Writings on an Ethical Life. New York: Ecco.

Stevenson, Leslie Forster, ed. (1999). The Study of Human Nature: A Reader, 2nd edition. New York: Oxford University Press. A companion volume to the editor's Ten Theories of Human Nature, collecting texts from twenty-four different sources.

Stevenson, Leslie Forster, and David L. Haberman. (2004). Ten Theories of Human Nature, 4th edition. New York: Oxford University Press. Includes three ancient religious views (Confucian, Hindu, biblical), five philosophical views (Plato, Kant, Marx, Freud, and Sartre), and two scientific views (behavioral and evolutionary psychology).

Watson, James D. (2003). DNA: The Secret of Life. New York: Knopf. A history of how genetics illuminates human nature.

Weikart, Richard. (2004). From Darwin to Hitler: Evolutionary Ethics, Eugenics, and Racism in Germany. New York: Palgrave Macmillan.

Wilson, Edward O. (1998). Consilience: The Unity of Knowledge. New York: Knopf. A defense of scientific materialism.

Zimmer, Carl. (2004). Soul Made Flesh: The Discovery of the Brain—and How It Changed the World. New York: Free Press. A history of Thomas Willis's neurology.

HUMAN NATURE

Debates over the nature of human nature have characterized social theory since it emerged in the Renaissance. As Thomas Sowell has argued, these debates generally take two forms: the optimistic and the pessimistic (Sowell 1987). The former position, associated with Rousseau and anarchists such as William Goodwin, holds that humans are essentially good but are turned bad by the institutions of their society. The latter position is rooted in the assumption that humans are fundamentally egoistic and selfish, thereby requiring either a strong state to regulate them or, in a less pessimistic account, an institution like the market to guide their affairs toward an optimal result.

For sociologists, neither position became the dominant way of thinking about human nature; instead, the plasticity of human experience was emphasized. Durkheim (1973) wrote the most important defense of a pluralistic approach to the subject, one that remains unsurpassed to this day in its clarity of presentation. Human nature is dualistic, he argued, speaking to the needs of both body and soul, the sacred and the profane, the emotional and the cognitive, and other such dualities. We are, in short, what we make ourselves. This version of a flexible approach to human nature would come to characterize contemporary theorists such as Parsons, who spoke of "much discussed 'plasticity' of the human organism, its capacity to learn any one of a large number of alternative patterns of behavior instead of being bound by its generic constitution to a very limited range of alternatives" (1951, p. 32).

In current sociological debates, the plasticity of human nature is emphasized by the general term social construction. If one argues that we ought to speak of gender roles rather than sex roles—the former is recognized to be the product of how people arrange their cultural rules, whereas the latter is understood to be fixed biologically—one is making a case for plasticity (Epstein 1988). Indeed, given the importance of feminism in contemporary theory, which tends to argue that "nothing about the body, including women's reproductive organs, determines univocally how social divisions will be shaped" (Scott 1988, p. 2), the strength of a plasticity approach to human nature is probably stronger than ever before.

Current research in many areas of sociology is premised on a social construction approach. Work stimulated by ethnomethodology is one clear case. In contrast to a Chomskian understanding of language as originating in rules hard-wired in the brain, the tradition of conversation analysis examines how human beings in real conversation twist and shape their utterances to account for context and nuance (Schegloff and Sacks 1979; Scheff 1986). Moreover, since the language we use is a reflection of the way we think, it is possible to argue that the mind itself is socially constructed, that the a priori nature of the way we think is relatively minimal (Coulter 1979). Accounts of sociological practice based on the assumption of plasticity do not end there. It has been argued that homosexuality is not driven by biological destiny but is a socially constructed phenomenon (Greenberg 1988). Morality, as well, can be understood as socially constructed (Wolfe 1989). Underlying a wide variety of approaches to sociology—from symbolic interactionism to social problems—is an underlying premise that human nature is not driven by any one thing.

The only dissent from a general consensus about human nature's plasticity is rational choice theory. At least among economists who believe that economic methodologies can be used to study social institutions such as the family, there is a belief that "human behavior is not compartmentalized, sometimes based on maximizing, sometimes not, sometimes motivated by stable preferences, sometimes by volatile ones, sometimes resulting in an optimal accumulation, sometimes not" (Becker 1976, p. 14). Yet there are many versions of rational choice theory; at least one of them, that associated with Jon Elster, is committed to methodological individualism but is also willing to concede the existence of a "multiple self" (Elster 1986). It is far more common in contemporary sociology to speak of egoism and altruism as existing in some kind of unstable combination rather than giving the priority totally to one or the other (Etzioni 1988).

Arguments about human nature, in turn, are related to the philosophical anthropology that shaped so much social theory. It has been a consistent theme of the sociological enterprise to argue that humans are different from other species. From the emphasis on homo faber in Marx and Engels, through Weber's notions about the advantages of culture, to Mead's account of why dogs and other animals are incapable of exchanging significant symbols, humans have been understood to possess unique characteristics that determine the organization of their society. Twentieth-century theorists such as Arnold Gehlen or Helmuth Plessner carried forward this tradition and are increasingly translated and read (for an overview, see Honneth and Joas 1988). Even Niklas Luhmann, whose work is heavily influenced by biology and cybernetics, can still claim that "the decisive advantage of human interaction over animal interaction stems from this elemental achievement of language" (1982, p. 72).

The most important shift in philosophical anthropology in recent years is a shift from an essentially materialist understanding of human capacities to an essentially mental one. Powers of interpretation and narrative, it has been argued, constitute the essential features of the human self (Taylor 1989). Just as an argument about the plasticity of human nature enables sociology to avoid reduction into psychological categories, an emphasis on the interpretive powers of humans prevents a reduction of sociology to sociobiology and other basically algorithmic ways of thinking about evolution.

As with the issue of plasticity, not all sociologists agree either that there are specific human characteristics or that, if there are, they ought to be understood as primarily mental and interpretive. Sociobiologists argue not only that humans are driven by their genetic structure more than they would like to believe but also that other animals also possess cultural skills. There is therefore no fundamental difference between human and nonhuman species, they are merely points along a continuum (Lumsden and Wilson 1981). Both sociologists and anthropologists, consequently, have argued for the use of sociobiological approaches in the social sciences (Lopreato 1984; Rindos 1986; Wozniak 1984), although there are also critics who question such an enterprise (Blute 1987).

In the 1990s, sociobiology, now often called evolutionary psychology, was something of a growth industry. Edward O. Wilson, who did so much to originate the field, sees the possibility of a unified approach to knowledge, one in which the laws of human interaction could eventually be deduced from the physical and the biological sciences (Wilson 1998). In the meantime, others influenced by evolutionary psychology have argued that cultural products such as language and mind can be understood through the laws of evolution (Blackmore 1999; Lynch 1996). Even such specific cultural products as novels and works of art are formed by processes of cultural selection, it has been argued (Taylor 1996). While still something of a minority point of view, trends such as these are premised on the idea that the natural sciences, especially biology, offer a better model for understanding human societies than the sociological tradition as dervived from Durkheim, Weber, and Mead.

Another challenge to the anthropocentric view that social scientists have taken toward humans has arisen with cognitive science and artificial intelligence. Whereas classical sociological theory compared humans to other animal species, we can now compare them to machines. Computers, after all, process information just as human brains do, use language to communicate, and reason, and can, especially in new approaches to artificial intelligence called connectionist, learn from their mistakes. There are, consequently, some efforts to apply artificial intelligence to sociology just as there are efforts to use the insights of sociobiology (Gilbert and Heath 1986), although here, again, there are strong critical voices (Wolfe 1991; Woolger 1985). In the more recent work of Niklas Luhmann, as well as in the writings of some other theorists, emphasis is placed on information science, systems theory, even thermodynamics—all of which are approaches based on a denial that human systems require special ways of understanding that are different from other systems (Bailey 1990; Beniger 1986; Luhmann 1989).

In spite of efforts to develop sociological theory on the basis of algorithmic self-reproducing systems, it is unlikely that assumptions about the unique, interpretative, meaning-producing capacities of humans will be seriously challenged. It is the capacity to recognize the contexts in which messages are transmitted and thereby to interpret those messages that make human mental capacities distinct from any organism, whether natural or artificial, that is preprogrammed to follow explicit instructions. One reason humans are able to recognize contexts is precisely the plasticity of their mental capacities. The plastic theory of human nature, in short, overlaps with an emphasis on philosophical anthropology to produce an understanding of human behavior that does not so much follow already-existing rules so much as it alters and bends rules as it goes along.

Both understandings of human nature and accounts of specifically human capacities will be relevant to future efforts in sociological theory to reconcile micro and macro approaches. Although there has been a good deal of effort to establish a micro–macro link (Alexander et al. 1987), the more interesting question may turn out not to be not whether it can be done but whether (and how) it ought to be done. Systems theory and the information sciences provide a relatively easy way to make a link between parts and wholes: Each part is understood to have as little autonomy as possible, so that the system as a whole can function autonomously with respect to other systems. The micro, like a bit of information in a computer program, would be structured to be as dumb as possible so that the macro system itself can be intelligent. Nonhuman enterprises—computers on the one hand and the structure of DNA in other animal species on the other—show that there is a major bridge between the macro and the micro. But the cost of constructing that bridge is the denial of the autonomy of the parts, a high cost for humans to pay.

But the conception of human beings as preprogrammed rule followers is not the only way to conceptualize micro sociological processes. The traditions of ethnomethodology and symbolic interactionism, which are more compatible with notions emphasizing the plasticity of human nature, imagine the human parts of any social system as engaged in a constant process of renegotiating the rules that govern the system. When the micro is understood as plastic, the macro can be understood as capable of existing even in imperfect, entropy-producing states of disorder. Indeed, for human systems, as opposed to those of machines and other species, disorder is the norm, integration the exception. If there is going to be a micro–macro link in sociology, it may well come about not by denying human plasticity and uniqueness, but rather by accounting for the particular and special property humans possess of having no fixed nature but rather a repertoire of social practices that in turn make human society different form any other kind of system.

(see also: Evolution: Biological, Social, Cultural; Intelligence; Sex Differences)

references

Alexander, Jeffrey C., Bernhard Giesen, Richard Munch, and Neil J. Smelser 1987 The Macro–Micro Link. Berkeley: University of California Press.

Bailey, Kenneth D. 1990 Social Entropy Theory. Albany: State University of New York Press.

Becker, Gary 1976 The Economic Approach to HumanBehavior. Chicago: University of Chicago Press.

Beniger, James R. 1986 The Control Revolution: Technological and Economic Origins of the Information Society. Cambridge, Mass.: Harvard University Press.

Blackmore, Susan 1999 The Meme Machine. Oxford: Oxford University Press.

Blute, Marion 1987 "Biologists on Sociocultural Evolution: A Critical Analysis." Sociological Theory 5:185–193.

Coulter, Jeff 1979 The Social Construction of Mind. London: Macmillan.

Durkheim, Emile 1973 "The Dualism of Human Nature and Its Social Conditions." In Robert N. Bellah, ed., Emile Durkheim on Morality and Society: Selected Writings. Chicago: University of Chicago Press.

Elster, Jon, ed. 1986 The Multiple Self. Cambridge, U.K.: Cambridge University Press.

Epstein, Cynthia 1988 Deceptive Distinctions: Sex, Gender,and the Social Order. New Haven, Conn.: Yale University Press.

Etzioni, Amitai 1988 The Moral Dimension. New York: Free Press.

Gilbert, C. Nigel, and Christian Heath, eds. 1986 SocialAction and Artificial Intelligence: Surrey Conferences onSociological Theory and Method 3. Aldershot, U.K.: Gower.

Greenberg, David 1988 The Construction of Homosexuality. Chicago: University of Chicago Press.

Honneth, Axel, and Hans Joas 1988 Social Action andHuman Nature. Cambridge, U.K.: Cambridge University Press.

Lopreato, Joseph 1984 Human Nature and BioculturalEvolution. Boston: Allen and Unwin.

Luhmann, Niklas 1982 The Differentiation of Society, trans. Stephen Holmes and Charles Larmore. New York: Columbia University Press.

——1989 Ecological Communication, trans. John Bednarz. Chicago: University of Chicago Press.

Lumsden, Charles J., and Edward O. Wilson 1981 Genes,Mind, and Culture: The Coevolutionary Process. Cambridge, Mass.: Harvard University Press.

Lynch, Aaron 1996 Thought Contagion: How Beliefs SpreadThroughout Society. New York: Basic Books.

Parsons, Talcott 1951 The Social System. New York: Free Press.

Rindos, David 1986 "The Evolution of the Capacity for Culture: Sociobiology, Structuralism, and Cultural Selectiveness." Current Anthropology 27:315–332.

Scheff, Thomas J. 1986 "Micro-Linguistics and Social Structure: A Theory of Social Action." SociologicalTheory 4:71–83.

Schegloff, Emmanuel, and Harvey Sacks 1979 "Opening Up Closings." In Ray Turner, ed., Ethnomethodology:Selected Readings. Baltimore: Penguin.

Scott, Joan Wallach 1988 Gender and the Politics of History. New York: Columbia University Press.

Sowell, Thomas 1987 A Conflict of Visions. New York: William Morrow.

Taylor, Charles 1989 Sources of the Self: The Making of theModern Identity. Cambridge, Mass.: Harvard University Press.

Taylor, Gary 1996 Cultural Selection: Why Some Achievements Survive the Test of Time—and Others Don't. New York: Basic Books.

Wilson, Edward O. 1998 Consilience: The Unity of Knowledge. New York: Knopf.

Wolfe, Alan 1989 Whose Keeper?: Social Science and MoralObligation. Berkeley: University of California Press.

——1991 "Mind, Self, Society, and Computer: Artificial Intelligence and the Sociology of Mind." American Journal of Sociology 96:1073–1096.

Woolger, Steve 1985 "Why Not a Sociology of Machines?: The Case of Sociology and Artificial Intelligence." Sociology 19:557–572.

Wozniak, Paul R. 1984 "Making Sociobiological Sense out of Sociology." Sociological Quarterly 25:191–204.

ALAN WOLFE

HUMAN NATURE

The phrase "human nature" is multiply ambiguous. Some early modern thinkers such as Thomas Hobbes, John Locke, and Jean-Jacques Rousseau tended to mean by it the supposed nature of human beings before the advent of organized human society. But there is every reason to believe that human beings have always been highly social creatures, and that the idea of individuals coming together to form society is a myth.

Another ambiguity, exemplified in the opposition between Mencius and Hsun-tzu in the ancient Confucian tradition in China, and between differing traditions within Christianity, is over whether human nature is basically good and in need only of appropriate sustenance and education, or whether we are inherently evil and stand in need of discipline or radical transformation.

A further difference is between a conception of human nature as what is in each individual at birth (or, given modern understanding of genetics, at conception), as opposed to the nature of the fully formed adult after maturation, socialization and education. This has given rise to endless nature versus nurture debates.

The distinction between a priori and a posteriori truths allows us place both for philosophical analysis of concepts of human nature, and for the discovery of empirical facts in physiology, psychology, anthropology, sociology, and history.

A Priori Theory: Rationality

What is most distinctive of human beings as opposed to other animals—rationality, language, consciousness, self-consciousness, freewill, moral responsibility, the ability to love? (And must all these go together?) How would we recognize beings from outer space as having any of these capacities? Perhaps the most obvious criterion they would have to meet to count as rational thinkers and agents is that they should be able to give reasons for their beliefs and their actions, in language of some sort that we could come to understand.

What makes such rationality possible in us? Plato and René Descartes believed that we are essentially immaterial souls, so our distinctively rational nature lies beyond scientific investigation. But must minds, consciousness and rationality involve something nonmaterial, or are we made of matter alone? Aristotle saw our rationality as superimposed on what we share with the animals (perception and self-movement), which is itself superimposed on the basic functions of all life including plants (metabolism and reproduction). According to this understanding, we are animals of a special rational kind.

But even if we reject a dualism of substances, and say that mind or soul is whatever the brain enables us to do, we find an unavoidable duality of aspects. There are mental descriptions of our beliefs, desires, hopes and fears, and there are physical descriptions of neuron firings and chemical changes. We thus use an irreducible duality of explanations—justifying our actions and beliefs in terms of reasons, and explaining brain events in terms of their physiological causes.

Empirical Theory: Human Nature and Nurture

Into this a priori conceptual framework we can fit empirical discoveries about human nature (and perhaps one day, about other rational beings elsewhere). There are plenty of such facts about the structure and functioning of our bodies—it is surely the size and complexity of our brains that explains our linguistic and rational abilities. There are also facts about our mental capacities, for example our recognition of faces, our tendency toward pair-bonding, and the need of children for attachment to parents.

In the light of Charles Darwin's theory of evolution, we can offer a scientific account of how the basic physical and mental commonalities of humans have evolved on this planet. With the aid of genetics and the fossil record, scientists are now piecing together the complicated story of how the faculties of rational thought and agency have come to be embodied in the human species. But we have to be very careful in applying Darwinian theory to human phenomena. Sociobiologists and evolutionary psychologists have tended to exaggerate. It is highly disputable whether every detail of contemporary human behavior has an evolutionary explanation; for example, donations to charity, the pursuit of religious vocations, and politicians' decisions to go to war.

Our reasons for action involve our beliefs and values, expressed in terms of our culturally developed concepts. Culture is at least as crucial to the realities of our contemporary human nature as evolution. It is superimposed on basic human biology, of course. That there are some innate tendencies in human nature is indisputable—for example, our sexual behavior. But the forms sexuality takes vary considerably between societies, and over time, and in devotedly celibate individuals its expression may be suppressed. The details of our behavior depend on the particular culture we have been brought up in. In the high-tech capitalist economy that now dominates the world, much of the social influence is exerted through the power of money, advertising, and the media. But it should not be forgotten that much behavior depends on individual choices, as existentialists and religious traditions have emphasized.

Human Needs and Rights

Like Plato and Aristotle, Immanuel Kant offered an objective basis for ethics, appealing both to pure reason and to empirical facts about human nature. Though Kant seemed to want to derive morality from rationality alone, he can be seen as appealing to a fundamental moral principle of respect for all rational beings "as ends in themselves." In this, he was obviously inspired by the Judeo-Christian ideal of love for one's neighbor as oneself, whereas Plato and Aristotle were more selective in their bestowal of respect for others. Karl Marx's and Jean-Paul Sartre's sense of human possibilities and the injustice of their denial were surely also influenced by the Judeo-Christian tradition. The Confucian notion of benevolence, and the Hindu and Buddhist programs of detachment from self, seem to point in the same direction of universal compassion.

Respect for all rational beings implies recognition of the rights and needs of all human beings. Rights imply corresponding obligations on other people, and the most appropriate place for talk of rights is in the negative cases: the rights not to be killed, injured, tortured, enslaved, imprisoned without trial, or exploited for someone else's benefit.

In his "second ethics," Sartre thought of human needs as objective values which demand to be fulfilled, if human beings are to flourish. The notion of need applies at several levels. There are things we need to maintain life and health—air, water, carbohydrates, protein, vitamins, medicines. There are psychological needs—most fundamentally the need of children for loving care, and there are typical adult needs for friendship, for sexual fulfillment, and for children of one's own. There are also needs for education and group membership, and needs to work, or contribute in some way to society.

When a human need is not met, it does not follow that someone is to blame. But when a human right is abused, then some person or group or social agency has done or encouraged the killing or torture, the enslavement or exploitation. And why have they done it? The answer will typically involve their seeing some advantage to themselves. There may be sadistic individuals who find intrinsic pleasure in causing pain, and many more are prepared to inflict suffering in the name of a "greater" cause (nation, party, or church), but most people do what they see as best for themselves. As Kant said, there is a "radical evil" in human nature, which consists in the tendency to prefer one's own interests over those of everyone else. But this is consistent with saying that we also have a potential for goodness and love.

Love

In the light of scarcity of resources, and individual and social evils, can we still entertain any hope for ethical and social progress, like Kant and other Enlightenment thinkers? Scarcity may perhaps be alleviated by scientific discovery and technological ingenuity. But new affluence breeds new needs and demands. There is an inherently competitive streak in human nature; we constantly rank ourselves against others. Our competitive tendencies may be acceptable in business and sport and in scientific and artistic achievement, but they easily turn into ruthlessness, cheating or greed. They may help drive social and cultural progress, but they need limitation by higher ideals of compassion and the common good.

What remedies are there? The first step is surely to name the evils, to try to make people aware of what is wrong, in ourselves and in society. For we are adept at finding good names for what we do: there are many possibilities of self-justification, self-deception, Freudian repression or Sartrian bad faith, and what Marx called "ideology," which covers up exploitation.

The notion of rationality alone does not give us much guidance as to what is ultimately worth aiming at, which of our desires are to be encouraged and developed, and which should be suppressed or transformed. People can be superbly intelligent and energetically persistent in action, yet utterly selfish or perverse.

The notion of love is perhaps more promising, provided we distinguish it, as in the Christian tradition exemplified in C. S. Lewis, from erotic and parental love, and from merely human friendship (as in Aristotle). The New Testament presents us with the ideal of agape (divine love, traditionally translated as "charity"), as presented in I Corinthians 13, Galatians 5, and I John 4. Sigmund Freud thought it impossible to fulfill, but even that dour old pessimist Arthur Schopenhauer recognized the possibility of saintly renunciation of self (and also, aesthetic contemplation) as a way that human beings can sometimes escape the near-universal domination of biologically based "will."

See also Altruism; Egoism and Altruism; Evolutionary Ethics; Moral Psychology.

Bibliography

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Aristotle. Nichomachean Ethics. Books I and X. Translated by Sarah Broadie. Oxford: Oxford University Press, 2002.

Clark, Mary E. In Search of Human Nature. London: Routledge, 2002.

Freud, Sigmund. Civilization and its Discontents (1930). Translated by Joan Riviere. In The Standard Edition of the Complete Psychological Works of Sigmund Freud. Vol 21. London: Hogarth Press, 1953–1974.

Kant, Immanuel. Groundwork of the Metaphysic of Morals (1785). Translated by Mary J. Gregor. In Immanuel Kant: Practical Philosophy. Cambridge, U.K.: Cambridge University Press, 1996.

Kant, Immanuel. Religion within the Boundaries of Mere Reason (1793). Part 1. Translated by George di Giovanni. In Immanuel Kant: Religion and Rational Theology. Cambridge, U.K.: Cambridge University Press, 1996.

Lewis, C. S. The Four Loves. London: Fontana, 1963.

Marx, Karl. Selected Writings in Sociology and Social Philosophy. Edited by T. B. Bottomore and Maximilien Rubel. Harmondsworth: Penguin, 1963.

The Oxford Study Bible. New York: Oxford University Press, 1992.

Pinker, Steven. The Blank Slate: The Modern Denial of Human Nature. London: Allen Lane, 2002.

Plato. Phaedo; Republic. Books IV and IX. Translated by G. M. A. Grube. Indianapolis, IL: Hackett, 1992.

Rose, Steven, R. C. Lewontin, and Leon J. Kamin. Not in Our Genes: Biology, Ideology, and Human Nature. Harmondsworth: Penguin, 1984.

Schopenhauer, Arthur. The World as Will and Representation Vol. I (1819). Translated by E. F. J. Payne. New York: Dover, 1966.

Stevenson, Leslie, and David Haberman. Ten Theories of Human Nature. 4th ed. New York: Oxford University Press, 2004.

Wilson, Edward O. On Human Nature. Cambridge, MA: Harvard University Press, 1978.

Leslie Stevenson (2005)

human nature A variety of sociological writers refer to the concept of human nature in different contexts. Most frequently, however, the term implies a recognition of some core and loosely determining characteristics which are assumed to underlie human action and consciousness. The exact composition of these elements is a matter of debate. Some social and political theorists (such as Thomas Hobbes, Charles Darwin (see DARWINISM), Sigmund Freud, and utilitarians generally) have invested human nature with selfish and egoistic motives, perhaps emanating from deeper biological imperatives. Others—such as Jean-Jacques Rousseau, Karl Marx, and Peter Kropotkin—have linked human nature in varying degrees to co-operation and altruism. The most influential perspective in sociology, typified for example by the work of Max Weber, has been to view human nature as a consequence of human histories and experience, rather than any predetermined essence. Indeed, many recent social theorists (including Michel Foucault, social constructionists, and post-modernists generally) have rejected the very notion of human nature itself.