The Concept of Human Nature
The moral concerns people have about human nature rest on different positions on the very concept of what human nature is—different views, that is to say, of what one knows when one has an understanding of human nature. Some of these positions would require a full theory of human nature, but others do not.
Essentialist versus Evolutionary Views of Species
According to one long and deep philosophical tradition, to have a concept of human nature is to grasp the essence of the ontological category that (in this account) human nature is. This would be more than a mere description; it would provide a metaphysical explanation of why things in that category belong to the category. It would set out the “what it is to be” of that thing, as Aristotle’s language is sometimes translated.
Understanding the essence of human nature would amount to having a full theory of human nature. As typically understood, an “essence” is the concept that a particular thing embodies. The essence of a triangle, for example, is the definition of triangles that all particular triangles embody. The essence of gold is the molecular structure that characterizes gold. An essence explains the traits that a thing has. It is not reducible to those traits, however; it is unchanging and timeless. An essence has an existence of its own, and indeed it is, in a sense, more real than the items that partake of it. Further, essences are often held to relate things of different kinds to each other. An essence is unique; all the members of a given kind share an essence, and members of other kinds lack it. According to an ancient lineage of scholars whose work draws on Aristotle, the universe reflects God’s benevolent organization—a “great chain of being,” so to speak, of essences is often invoked to suggest that a kind is what it is by rational necessity and that the overall universe is also rationally ordered and necessary. We understand the order and necessity of the universe by grasping the essences that things in the universe embody.
This is a lot to take on. Fortunately, essentialism is not the only way of understanding the concept of “human nature.” Essentialism models itself after mathematics and physics, but biology is now understood along evolutionary and stridently nonessentialist lines. The evolutionary view makes no claim for the rational necessity of human nature, or for its immutability and timelessness, or that an account of human nature will show that human nature is rationally related to the rest of the universe. There need also be no requirement that what makes humans human is some trait that the members of other species entirely lack. Typically, looking at traits allows one to recognize species, but the traits that allow us to recognize humans as humans might all be found in some measure in other animals. And ultimately, in an evolutionary account, what really distinguishes species is not any claim about what traits characterize the members of the species, but the causal story that can be told about how the species appeared on the scene and how, through reproduction, it persists. In an evolutionary account, whether a given population of animals really counts as a “species” can be allowed to remain somewhat problematic and contestable.
If the evolutionary view of species makes sense, then the term “human nature” does not demarcate the set—it does not show what counts as a human being and what does not. Instead, it functions descriptively; it tells us what the members of the set happen to be like. Of course, because evolutionary stories are also stories about how species came to be what they are, we expect to be able to talk knowledgeably both about traits that distinguish species from each other and about traits that species share—to describe, for example, how dogs and cats are similar and how they differ. In the evolutionary view, this is to talk about species’ natures.
Talk about what dogs, cats, and other kinds of animals are like is unproblematic. And because humans are themselves animals—and only animals, in a Darwinian frame—then we should expect to be able to talk about human nature. Moreover, we should expect to make some headway in understanding human nature by studying our taxonomic neighbors, as Mary Midgley argues in Beast and Man (1979). What distinguishes human beings from other animals is typically held to be their possession of various capacities related to cognition, such as language, rationality, tool-making, morality, and culture, but there is no need to establish that any of these capacities are possessed only by humans; indeed, the evidence is mounting that they are capacities or extensions of capacities that animals also possess in differing forms and degrees. At the same time, as Midgley also emphasizes, we need not restrict ourselves to biology to learn about human nature. We will have to study humans sociologically and anthropologically, as Paul Ehrlich (2000) does in arguing that there is no unitary account of human nature, and in favor of thinking that, given the significance of culture in human ways of living, there are multiple human natures.
Thinking this way leads to lists, while also ensuring that any one list will be less than completely satisfying. Larry Arnhart offers a list of twenty natural desires
“that are so deeply rooted in human nature that they will manifest themselves in some manner in every human society” (1998, p. 29). Martha Nussbaum offers ten “central capabilities” that represent “a type of overlapping consensus on the part of people with otherwise very different views of human life” (2000, p. 76). Such lists often seem to be on to something; at the same time, they sometimes seem pat and open to quibbling. Arnhart includes sexuality on his list; Nussbaum subsumes it under “bodily integrity.” Nussbaum includes “affiliation,” Arnhart “relationships” but also the more explicitly community-minded “sociality.” Nuss- baum includes “life” and “bodily health” but not “embodiment” per se, as Leon Kass certainly would. In short, questions arise that can look like matters of judgment: Why is this left off? Is that really a general feature of human nature? Why not break that one into two items? Arnhart notes that the items on the list need not be true of every individual; it is enough that they are “tendencies or proclivities” that are manifest on the population level (1998, p. 30). And both Arnhart and Nussbaum observe that the items may be instantiated very differently in different societies. We must see all such lists as open to challenge and revision. Nussbaum emphasizes this point: “the list remains open-ended and humble; it can always be contested and remade” (2000, p. 77).
Another broader point must be made here: what the term “nature” means in general also depends on our interests and on the conceptual frame within which we are operating. John Stuart Mill famously sought to dismiss the thought that “nature” can have intrinsic moral value by showing that it refers to many different things, many of them undesirable, and that the two most common ways of understanding “nature” can give no moral direction. Under one common understanding, “nature” refers to everything that adheres to the laws of nature; under the other, it refers only to that which excludes human interference or involvement. Understood in the first way, all human action is natural; understood the second way, all human action is unnatural. Either way, the concept cannot help us mark off some human actions as according with nature and others as violating it (1961, pp. 368 ff.).
The response to Mill can only be to acknowledge the complexity and work with it. When we are doing physics, everything that is, is natural. When we are shopping for food, deciding where to spend a vacation, or arguing about how national forests are maintained, we will see certain ways in which humans can manipulate the world around them as altering natural states of affairs. For the anthropologist and the cosmetic surgeon, perhaps everything that humans can do to themselves is natural. For the administrator of a sports league, certain things humans can do to themselves may not count as natural. Within these contexts, it will often be clear enough whether something counts as “natural,” but we will also come up against situations in which we are not entirely sure how to carry on with the term, and we must adjudicate these hard cases as best we can, by appealing to standards developed within the context in which we are operating.