Dan Fessler, an anthropologist with an interest in evolutionary psychology, has some thoughts on the abuse of the word “natural” in contemporary moral and political discourse:
Controversy erupted in Kanab, Utah recently when the city council resolved to promote what it described as the “natural family,” a monogamous heterosexual marriage producing multiple children. This position is not unique to the Kanab resolution, having been promulgated by conservative think tanks, pundits, and politicians on the national stage. Because the word “natural” carries a lot of weight in such arguments, it is important to note that, by employing it, the council members of Kanab are committing two fundamental errors, one empirical, the other philosophical. First, let’s examine the facts.
“Natural” frequently refers to one of three sources of evidence, namely tradition, human biology, or divine prescription. Anthropology reveals that human societies are characterized by an array of marriage patterns, including monogamy, polygyny (one husband, multiple wives), and polyandry (one wife, multiple husbands). A common pattern is a combination of monogamy and moderate polygyny — most men have a single wife, but some men (generally those highest in prestige and/or power) have multiple wives. If by “natural” one means “prevailing in human traditions,” then the natural human family is quite different from that advocated by social conservatives. Perhaps proponents of the “natural family” disregard other cultures, equating “natural” only with the traditions of their forbearers. However, given their state’s history of polygyny, the council of Kanab is on shaky ground promoting monogamous marriage via this line of reasoning.
“Natural” is often used to justify practices by appeal to biology — those who wish to define marriage as exclusively heterosexual, or who advocate large family size, make reference to the complementarity of male and female bodies, the fact that the clear purpose of genitalia is procreation, etc. What does the study of reproductive biology tell us about the natural human family? The foremost feature of humans in this regard is that males are larger than females. Across species, this pattern is associated with polygynous mating. The explanation for this pattern is simple: natural selection favors larger male size whenever males compete to control access to multiple females. In monogamous species, males are no larger than females — because every guy gets a gal, there is no competitive advantage in being big. Across species, the pattern characterizing humans (males being about 10-15% larger) is associated with moderately polygynous mating. Appealing to biology thus does not support the vision of the natural family as one man and one woman (I leave for another essay what biology tells us about the naturalness of exclusively heterosexual behavior — suffice it to say that social conservatives won’t be pleased).
Lastly, the term “natural” is sometimes used to mean “dictated by God.” While those who employ the term in this fashion are unlikely to be swayed by evidence from either cultural anthropology or evolutionary biology, nevertheless, the religious traditions invoked often offer no more support for the view that monogamy is the natural form of human marriage. I leave it to theologians to debate the doctrines of the Church of Jesus Christ of Latter-Day Saints, but the history of this organization clearly indicates that religious teachings on the subject of marriage can be interpreted in a variety of ways. Such a history is not surprising, as there are Biblical precedents for a wide variety of marital arrangements, notably including polygyny.
So, do I advocate polygynous marriage? Absolutely not. The reason has to do with the philosophical error committed by those who appeal to “natural” when prescribing behavior. Whether one means “prevailing around the globe” or “reflecting human biology,” the term “natural” should never be taken as providing moral guidance, as explanations of behavior do not constitute justifications. Many abhorrent actions are both common and scientifically explicable —scholars can study, and explain, homicide or the abuse of stepchildren, yet no reasonable person would argue that, because these actions are “natural” by either definition, they should be accepted. Of course, the Kanab city council might respond that their definition of “natural” only refers to their own traditions or beliefs. However, given that traditions change and beliefs are subject to interpretation, appealing to “natural” in this way is a rhetorical trick, giving the impression of immutability and incontestability to things that are anything but. Reasonable people should discuss the moral principles underlying their positions, instead of smuggling unstated and ill-considered assumptions into the discussion by referring to what is natural.
Footnote Could “Kanab” be cognate with “cannabis”? That would explain a lot.