Why do people infer “ought” from “is”?

Tworek and Cimpian offer an interesting perspective, doing experiments illustrating how we ascribe intrinsic value to what is customary. I give the start of their introduction setting the context, and then their abstract:

In his dissent from the Supreme Court decision recognizing a federal constitutional right for people to marry a same-sex partner, Chief Justice Roberts noted that heterosexual marriage has been around “for millennia” in societies all over the world: “the Kalahari Bushmen and the Han Chinese, the Carthaginians and the Aztecs”. A possible reading of this remark is that we should take what is typical as a signpost for what is good—how things ought to be.1 Whatever the correct interpretation here, the tendency to move seamlessly from “is” to “ought” is a mainstay of everyday reasoning. However, the validity of such “is”-to-“ought” inferences (or ought inferences) is at best uncertain. The mere existence of a pattern of behavior does not, by itself, reveal that the behavior is good.2 For instance, slavery and child labor were common throughout history, and still are in some parts of the world, yet it does not follow that people ought to engage in these practices. Why, then, do people frequently draw ought inferences and find them persuasive?

Abstract

People tend to judge what is typical as also good and appropriate—as what ought to be. What accounts for the prevalence of these judgments, given that their validity is at best uncertain? We hypothesized that the tendency to reason from “is” to “ought” is due in part to a systematic bias in people’s (nonmoral) explanations, whereby regularities (e.g., giving roses on Valentine’s Day) are explained predominantly via inherent or intrinsic facts (e.g., roses are beautiful). In turn, these inherence-biased explanations lead to value-laden downstream conclusions (e.g., it is good to give roses). Consistent with this proposal, results from five studies (N = 629 children and adults) suggested that, from an early age, the bias toward inherence in explanations fosters inferences that imbue observed reality with value. Given that explanations fundamentally determine how people understand the world, the bias toward inherence in these judgments is likely to exert substantial influence over sociomoral understanding.