How do people know?

To fully understand processes of knowing and knowledge acquisition, it is necessary to examine people's understanding of their own knowing. Individual and developmental differences in what it means to know something, and hence in the criteria for justifying knowledge claims, have potentially wide-ranging implications. In providing support for a claim, young children have difficulty differentiating explanation of why a claim makes sense and evidence that the claim is true. Epistemic understanding progresses developmentally, but substantial variation remains among adults, with few adults achieving understanding of the complementary strengths and weaknesses of evidence and explanation in argument. Epistemic understanding shapes intellectual values and hence the disposition (as opposed to competence) to exercise intellectual skills. Only its most advanced levels support a disposition to engage in the intellectual effort that reasoned argument entails. The sample case of juror reasoning illustrates how epistemic understanding underlies and shapes intellectual performance.