of Firstness, Secondness, and Thirdness mentioned above occupy a central position in Peirce’s metaphysics. Especially in his later writings he emphasized the reality and metaphysical irreducibility of Thirdness, and defended the view that general phenomena (for example, general laws) cannot be regarded as mere conjunctions of their actual individual instances. This view was associated with Peirce’s synechism, the doctrine that the world contains genuinely continuous phenomena. He regarded synechism as a new form of Scholastic realism. In the area of modalities Peirce’s basic categories appear as possibility, actuality, and necessity. Here he argued that reality cannot be identified with existence (or actuality), but comprises real (objective) possibilities. This view was partly based on his realization that many conditional statements, for instance the ‘practical’ conditionals expressing the empirical import of a proposition (in the sense of the Pragmatic Maxim), cannot be construed as material or truth-functional conditionals, but must be regarded as modal (subjunctive) conditionals. In his cosmology Peirce propounded the doctrine of tychism, according to which there is absolute chance in the universe, and the basic laws of nature are probabilistic and inexact. Peirce’s position in contemporary philosophy. Peirce had few disciples, but some of his students and colleagues became influential figures in American philosophy and science, e.g., the philosophers James, Royce, and Dewey and the economist Thorstein Veblen. Peirce’s pragmatism became widely known through James’s lectures and writings, but Peirce was dissatisfied with James’s version of pragmatism, and renamed his own form of it ‘pragmaticism’, which term he considered to be ‘ugly enough to keep it safe from kidnappers.’ Pragmatism became an influential philosophical movement during the twentieth century through Dewey (philosophy of science and philosophy of education), C. I. Lewis (theory of knowledge), Ramsey, Ernest Nagel, and Quine (philosophy of science). Peirce’s work in logic influenced, mainly through his contacts with the German logician Ernst Schröder, the model-theoretic tradition in twentieth-century logic.
There are three comprehensive collections of Peirce’s papers: Collected Papers of Charles Sanders Peirce (1931–58), vols. 1–6 edited by Charles Hartshorne and Paul Weiss, vols. 7–8 edited by Arthur Burks; The New Elements of Mathematics by Charles S. Peirce (1976), edited by Carolyn Eisele; and Writings of Charles S. Peirce: A Chronological Edition (1982–).
See also DEWEY, JAMES, PHILOSOPHY OF SCIENCE , PRAGMATISM , TRUTH , TYCHIS. R.Hi. Peirce’s law, the principle ‘((A P B) P A) P A’, which holds in classical logic but fails in the eyes of relevance logicians when ‘ P’ is read as ‘entails’. See also IMPLICATION, RELEVANCE LOGI. G.F.S.