Before examining various approaches to the explanation of religion, we must first agree about what it is that we hope to be able to explain. In short, we must agree on what we mean by ‘religion’. Anthropology, like other immature sciences—and especially those whose basic vocabulary is derived from natural languages—continues to be plagued by problems of definition. Key terms in our lexicon—culture’, ‘social system’, ‘needs’, ‘marriage’, ‘function’, and the like—continue to evoke wide differences in meaning and to instigate heated controversy among scholars. Frequently the differences and controversies stem from differences in the types of definition employed.