Our study, recently published in Psychological Science, suggests that preschoolers have a tendency to infer the presence of social norms based on minimal evidence – that is, in situations in which an adult merely performs an arbitrary action spontaneously for herself without giving any pedagogical or explicit cues that this one-shot behavior is governed by collective norms. It seems sufficient that the spontaneous acts are intentional as opposed to accidental. In other words, children autonomously derive what ought to be (generalizable and prescribed actions) from what is (observed behavior) – and thus commit the is-ought fallacy, as originally pointed out by the philosopher David Hume some 300 years ago.
Schmidt, M. F. H., Butler, L. P., Heinz, J., & Tomasello, M. (2016). Young children see a single action and infer a social norm: Promiscuous normativity in 3-year-olds. Psychological Science, 27(10), 1360–1370.