Equality Held Hostage to an Empirical Claim

There are three theories of human nature enjoying widespread support at present. For convenience, I’ll tag each one of them with a single adjective. Religious. Our species Homo sapiens is the special creation of God, either as a one-off miracle or by God-guided evolution. Human nature is a mix of attributes, some natural ones arising from plain biology, some supernatural ones inserted by God. We are the Chosen Species. The God-given attributes are unique to our species. They are the same in all human populations, forming the foundation of our essential equality. Their existence is independent of our biological nature, even to the degree that they can continue to exist after our deaths. Being nonbiological, they don’t evolve, even if other features of the living world do, so that our evolution, if it ever took place, ended (except perhaps for some incidental biological features) when God decreed we have these supernatural attributes. These God-given attributes include the moral sense, which accesses transcendent truths—i.e., truths that do not dwell in the world of matter. God rules! Cultural. Our species arose, like all other species, from the ordinary processes of evolution. However, these processes ceased in the early history of the species, leaving us with a human nature uniform across all populations and unchanging over time, forming the foundation of our essential equality. This human nature has very little innate structure and is extremely plastic. By placing it in a suitable environment, or applying suitable pressures, the mind (and therefore the behavior, which issues from the mind) can be shaped in any way at all. “Human nature” does not really exist independent of the environment an individual happens to be in, especially that part of the environment made up of other human beings—“the culture.” Moral standards are arbitrary, and are taken in by the individual from the culture. Culture rules! Biological. Our species arose, like all other species, from the ordinary processes of evolution, which have continued to the present day. Human nature is a collection of characteristics all susceptible to biological explanation. Some characteristics of a person’s nature can be shaped to some degree by “cultural” (i.e., social or environmental) forces; some cannot. Human beings are a part of the living world, and nothing more. Our equality consists in being members of a single species; though our species, like any other with very wide distribution, exhibits regional differences. The characteristics of an individual human being are templated in his genome. They may be somewhat modified by womb events or life experiences; or they may need to be “instantiated” by postpartum environment. (An individual’s genome may, for example, predispose him to be eloquent or tongue-tied when using language; but which language he uses will depend on his childhood environment.) The repertoire of human behaviors, and of ideas, including moral ideas, about behavior, are innate, the result of evolutionary processes acting on our social lives across many generations. Biology rules! For convenience in what follows, I’ll label adherents of these three views with the more or less made-up words “Religionists,” “Culturists,” and “Biologians.” Each point of view has a history. Religionism emerges from core features of human thinking, as described by cognitive scientists like Pascal Boyer (Religion Explained, 2001), Scott Atran (In Gods We Trust, 2002), and Bruce Hood (Supersense, 2009). Culturism has roots in the tabula rasa (“blank slate”) theories of Aristotle and Locke. It was put into its modern form by German anthropologist Adolf Bastian (1826–1905). Bastian coined the phrase “the psychic unity of mankind.” His student Franz Boas brought these ideas to the United States, becoming the most influential American anthropologist of the early twentieth century. Biologism is just ordinary scientific method applied to humanity.

The past 30 years of research in intelligence has produced a wealth of knowledge about the causes and consequences of differences in intelligence between individuals, and today mainstream opinion is that individual differences in intelligence are caused by both genetic and environmental influences. Much more contentious is the discussion over the cause of mean intelligence differences between racial or ethnic groups. In contrast to the general consensus that interindividual differences are both genetic and environmental in origin, some claim that mean intelligence differences between racial groups are completely environmental in origin, whereas others postulate a mix of genetic and environmental causes. In this article I discuss 5 lines of research that provide evidence that mean differences in intelligence between racial and ethnic groups are partially genetic. These lines of evidence are findings in support of Spearman’s hypothesis, consistent results from tests of measurement invariance across American racial groups, the mathematical relationship that exists for between-group and within-group sources of heritability, genomic data derived from genome-wide association studies of intelligence and polygenic scores applied to diverse samples, and admixture studies. I also discuss future potential lines of evidence regarding the causes of average group differences across racial groups. However, the data are not fully conclusive, and the exact degree to which genes influence intergroup mean differences in intelligence is not known. This discussion applies only to native English speakers born in the United States and not necessarily to any other human populations.