Peirce's Pragmatic Maxim and Theory of Signs

Charles Sanders Peirce (1839–1914), born in Cambridge, Massachusetts, the son of the Harvard mathematician Benjamin Peirce, founded pragmatism as a philosophical method in a series of essays published in Popular Science Monthly under the collective title "Illustrations of the Logic of Science." The second of these, "How to Make Our Ideas Clear" (January 1878), formulates the doctrine that would define the entire movement: the pragmatic maxim. Peirce states it thus: "Consider what effects, that might conceivably have practical bearings, we conceive the object of our conception to have. Then, our conception of these effects is the whole of our conception of the object." The maxim is offered as a rule of logic for achieving the highest of three grades of conceptual clearness — beyond mere familiarity and beyond abstract definition — by tracing a concept down to the totality of its conceivable experimental or practical consequences. Peirce illustrates the method with the concept of "hardness": to say a diamond is hard means nothing more than that it will resist scratching by other substances, a claim entirely cashed out in terms of what would happen under specifiable conditions.