Abstract: | This study examined the criteria that middle school students, nonscientist adults, technicians, and scientists used to rate the validity of conclusions drawn by hypothetical students from a set of evidence. The groups' criteria for evaluating conclusions were considered to be dimensions of their epistemological frameworks regarding how knowledge claims are justified, and as such are integral to their scientific reasoning. Quantitative and qualitative analyses revealed that the responses of students and nonscientists differed from the responses of technicians and scientists, with the major difference being the groups' relative emphasis on criteria of empirical consistency or plausibility of the conclusions. We argue that the sources of the groups' differing epistemic criteria rest in their different spheres of cultural practice, and explore implications of this perspective for science teaching and learning. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 663–687, 2001 |