What is it about human nature that makes our species capable of thinking scientifically? Inspired by the debate he set up between Noam Chomsky and Jean Piaget, Scott Atran traces the development of Natural History from Aristotle to Darwin, and demonstrates how the science of plants and animals has emerged from common conceptions of folk biology. The author proceeds not only from the more traditional philosophical, historical, or sociological perspectives, but from a point of view which he considers to be more basic and necessary to all of these: that of cognition. He applies a 'cognitive' perspective to an explanation of the successive scientific incarnations, transformations, and mutations of what Hume called 'mankind's original stock of ideas'.