Bacon's inductivist philosophy of science divides thinkers into the scientific and the prejudiced, using as a standard the up-to-date science textbook. Inductivists regard the history of science as progressing smoothly, from facts rather than from problems, to increasingly general theories, undisturbed by contending scientific schools. Conventionalists regard theories as pigeonholes for classifying facts; history of science is the development of increasingly simple theories, neither true nor false. Conventionalism is useless for reconstructing and weighing conflicts between schools, and overemphasizes science's internal organic growth. For Popper, not for inductivists or conventionalists, the successful criticism of theories is the heart of science. Popper's view admits the existence of valuable errors and enables us to avoid being wise after the event, thereby improving our understanding of the history of science through reconstructions of the actual interplay of theories and facts.