Auguste Comte was a 19th century French philosopher who developed the idea of the three stages of human thought: the theological stage, the metaphysical stage, and the positive stage. He argued that societies and human knowledge progress through these stages according to natural law. The theological stage explains phenomena through supernatural causes, the metaphysical stage replaces supernatural agents with abstract forces, and the positive stage recognizes the impossibility of absolute truth and focuses on discovering the actual laws of phenomena through observation and reasoning.