  By the time Peirce wrote on probability, the concept and its calculus were well over two hundred years old. The probability calculus itself had become more or less standardized by Peirce’s time, and indeed Peirce’s own axioms for the calculus are more or less the same that Kolmogoroff gives for his “elementary theory of probability.” By contrast with the calculus, the philosophical theory of the meaning of probability was hotly disputed. Two sides to the dispute existed. There were the subjectivists, or “conceptualists,” as Peirce designated them. These believed that probability was a measure of the strength of belief actually accorded to a proposition or a measure of the degree of rational belief that ought to be accorded to a proposition. Among the defenders of this sort of view, Augustus de Morgan and Adolphe Quetelet were major figures.  And there were the objectivists, or “materialists,” as Peirce designated them. These believed that probability was a measure of the relative frequency with which an event of some specific sort repeatedly happened.  John Venn was a major defender of this sort of view. Pierre Simon Laplace had spoken sometimes in a subjectivist way, sometimes in an objectivist way; but his arguments basically depended on a subjectivist interpretation of probability.