But Comte had a more methodical and scientific mind, and he thought that Saint-Simon was premature in drawing conclusions as to the reformation of societies and industries before the positive philosophy had been constructed. He published—he was then only twenty-two—in 1822 a “Plan of the scientific operations necessary for the re-organisation of society,” which was published under another title two years later by Saint-Simon, and it was over this that the friends quarrelled. This work contains the principles of the positive philosophy which he was soon to begin to work out; it announces already the “law of the Three Stages.”
The first volume of the “Cours de philisophie positive” appeared in 1830; it took him twelve years more to complete the exposition of his system. [Footnote: With vol. vi., 1842.]
The “law of Three Stages” is familiar to many who have never read a line of his writings. That men first attempted to explain natural phenomena by the operation of imaginary deities, then sought to interpret them by abstractions, and finally came to see that they could only be understood by scientific methods, observation, and experiment—this was a generalisation which had already been thrown out by Turgot. Comte adopted it as a fundamental psychological law, which has governed every domain of mental activity and explains the whole story of human development. Each of our principal conceptions, every branch of knowledge, passes successively through these three states which he names the theological, the metaphysical, and the positive or scientific. In the first, the mind invents; in the second, it abstracts; in the third, it submits itself to positive facts; and the proof that any branch of knowledge has reached the third stage is the recognition of invariable natural laws.
But, granting that this may be the key to the history of the sciences, of physics, say, or botany, how can it explain the history of man, the sequence of actual historical events? Comte replies that history has been governed by ideas; “the whole social mechanism is ultimately based on opinions.” Thus man’s history is essentially a history of his opinions; and these are subject to the fundamental psychological law.