Auguste Comte
The law of three stages is a socio-historical idea of Auguste Comte.  Comte said that knowledge developed in three stages. The first stage is the "theological" stage, in which Comte says that people use religion or gods to explain why things happen or where things came from.  The second stage is the "metaphysical" or "abstract" stage, where people use philosophy and abstract ideas to think about their beliefs and explain things.  The last stage is the "positive", regarding to the three stages of positivism. Comte said that society could shift into a positivist society if the sciences, including sociology, are all used to explain things.