Semiotic theory of Charles Sanders Peirce

Charles Sanders Peirce began writing on semiotic, which he also called semeiotic, meaning the philosophical theory of signs, in the 1860s, around the time that he devised his system of three categories. During the 20th Century the term "semiotics" was adopted to cover sign researches including Saussure's semiology which began in linguistics as a completely separate tradition.

Peirce adopted the term semiosis and defined it to mean an "action, or influence, which is, or involves, a coöperation of three subjects, such as a sign, its object, and its interpretant, this tri-relative influence not being in any way resolvable into actions between pairs". This specific type of triadic relation is fundamental to Peirce's understanding of "logic as formal semiotic". By "logic" he meant philosophical logic. He eventually divided (philosophical) logic, or formal semiotic, into (1) speculative grammar, or stechiology on the elements of semiosis (sign, object, interpretant), how signs can signify and, in relation to that, what kinds of signs, objects, and interpretants there are, how signs combine, and how some signs embody or incorporate others; (2) logical critic, or logic proper, on the modes of inference; and (3) speculative rhetoric, or methodeutic, the philosophical theory of inquiry, including his form of pragmatism. His speculative grammar, or stechiology, is this article's subject.

Peirce conceives of and discusses things like representations, interpretations, and assertions broadly and in terms of philosophical logic, rather than in terms of psychology, linguistics, or social studies. He places philosophy at a level of generality between mathematics and the special sciences of nature and mind, such that it draws principles from mathematics and supplies principles to special sciences. On one hand, his semiotic does not resort to special experiences or special experiments in order to settle its questions. On the other hand, he draws continually on examples from common experience, and his semiotic is not contained in a mathematical or deductive system and does not proceed chiefly by drawing necessary conclusions about purely hypothetical objects or cases. As philosophical logic, it is about the drawing of conclusions deductive, inductive, or hypothetically explanatory. Peirce's semiotic, in its classifications, its critical analysis of kinds of inference, and its theory of inquiry, is philosophical logic studied in terms of signs and their triadic relations as positive phenomena in general.

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