The law of three stages is an idea developed by Auguste Comte in his work The Course in Positive Philosophy. It states that society as a whole, and each particular science, develops through three mentally conceived stages: (1) the theological stage, (2) the metaphysical stage, and (3) the positive stage.

According to Comte, human societies moved historically from a theological stage, in which the world and the place of humans within it were explained in terms of gods, spirits, and magic; through a transitional metaphysical stage, in which such explanations were based on abstract notions such as essences and final causes (see teleology); and finally to a modern, “positive” stage based on scientific knowledge.

Comte elaborated the Law of Three Stages of human thought (or the Law of Human Progress): theological, metaphysical and positive. These Stages, he thought, charac­terised the development of both human knowledge and of society, which correspondingly developed from a military to a legal, and finally to an industrial stage.

Comte felt that one of the most basic laws of human organization is the “law of the three stages,” a notion clearly influenced by the philosophical concepts of Turgot, Condorcet, and Saint-Simon. He termed these stages the theological–military, metaphysical–judicial, and scientific–industrial or “positivistic.”