Justifying an ideal first pregnancy age: Vernacular science knowledge and the facilitation of lay argument

Members of the lay public often draw from vernacular science knowledge-or metaphors, images, and terms related to technical science-to make normative assessments about behavior. Yet, little is known about vernacular science knowledge in terms of its forms and functions. In a national survey, US adults ( N = 688) were asked to identify an ideal age for first pregnancy, and to explain their decision. Participants drew from arguments related to hormonal processes, the language of risk, and the quality and quantity of "eggs" to navigate and identify an ideal timeline for first pregnancy. Their responses illustrated patterns of justification that involved the (a) employment of scientific concepts as heuristic cues for critical analysis, (b) conflation of details, and (c) synecdochal explication. These findings reveal some of the key ways in which vernacular science knowledge may shape the trajectory of lay argument in a range of contexts.