This article briefly considers current positions about whether the inclusion of the perspectives and interests of marginalised groups in the construction of knowledge is of epistemic value. It is then argued that applied social epistemology is the proper epistemic stance to take in evaluating this question. Theorists who have held that diversity makes an epistemic contribution are interpreted as attempting to reform social pathways to knowledge in ways that make true belief more likely. Thus, the demand for diversity challenges the individualistic and a priori nature of traditional epistemology. This stance has consequences for education. It supports greater attention to helping students examine the testimonial bases for their beliefs. And it prepares students for their role as citizens in supporting policies that maintain credible inclusive institutions of public knowledge.