Positivism was a method for studying society proposed by Auguste Comte, a French philosopher who founded the study of sociology.
Comte's bias was against metaphysics, a philosophy based largely on speculation about the nature of things. Comte believed that philosophy, at least in this sense, could not adequately study society. He proposed a new method of study, which he originally called positivism. Positivism would base all conclusions on observation. This removed positivism from the field of philosophy and placed it in the field of science, where knowledge is based on empirical facts.
Empirical facts are those that can be measured and tested. They are the basis of all science. This was the theme of his book, "Positivie Philosophy."
Unfortunately, toward the end of his life, Comte "invented" a religion of positivism. It was a religion that would have no god, but 20,000 positivistic priests. At this point, many of his supporters deserted him. Some asked him to delineate between the religion of positivism and the science of positivism.
Eventually, he revised "Positive Philosophy," renaming the science of positivism by taking the Latin root "Socius" (meaning "group" or "relationship") and coupling it with the Greek work "logos" (meaning "knowledge" or "study"). Hence, sociology.
After Comte's death, Emile Durkheim really developed the field of sociology by insisting that this "new" science concentrate on the study of "social facts." Later, this strict relience on positivism...