Stewart Guthrie's work in the cognitive science of religion (e.g., "A cognitive theory of religion," 1980, and Faces in the Clouds,1993) is widely considered a foundation of that field. Guthrie builds on David Hume's theory of religion as anthropomorphism by adding Darwinian natural selection and the logic of Pascal's Wager. His central argument is that anthropomorphism (which, unlike religion, is a human universal and has parallels in other animals) results in part from an evolved cognitive strategy. The strategy is to resolve uncertainty about ambiguous phenomena by interpreting them first as whatever possibility matters most. For humans, that possibility usually is that the phenomenon is personal or the result of personal action. Guthrie continues to expand and sharpen his account of anthropomorphism.