With Wayne Proudfoot's work on religious experience we see a rather dramatic departure from some of the previous essays in this volume that assume the universality, and particularly, the self-evident nature, of religious experience. Proudfoot is a scholar of the philosophy of religion at Columbia University whose work has focused on religious experience, pragmatism and the influence of William James, theories and methods in the study of religion, and modern Protestant thought. His publications include William James and a Science of Religion: Reexperiencing the Varieties of Religious Experience (2004); Religious Experience (1987); and God and the Self: Three Types of Philosophy of Religion (1976).

What has made Proudfoot's scholarship both popular and controversial has been his advocacy for reductionism. Reductionism refers to a way of accounting for a complex phenomenon by pointing to the constituent parts that comprise it; in the case of religious phenomena, a reductionist might look to economic, social, or psychological sources to better understand the source of the event or to account for its existence. This approach stands in opposition to non-reductionist models, which might argue that religion is sui generis (that is, a completely unique thing irreducible to other elements), or that the perspective and interpretive ability of the religious participant should be privileged above all others.