For ease of reference, here are two variants of Peirce’s 1902 definition of a sign, which he gives in the process of defining logic.

### Selections from C.S. Peirce, “Carnegie Application” (1902)

#### No. 12. *On the Definition of Logic*

Logic will here be defined as *formal semiotic*. A definition of a sign will be given which no more refers to human thought than does the definition of a line as the place which a particle occupies, part by part, during a lapse of time. Namely, a sign is something, *A*, which brings something, *B*, its *interpretant* sign determined or created by it, into the same sort of correspondence with something, *C*, its *object*, as that in which itself stands to *C*. It is from this definition, together with a definition of “formal”, that I deduce mathematically the principles of logic. I also make a historical review of all the definitions and conceptions of logic, and show, not merely that my definition is no novelty, but that my non-psychological conception of logic has *virtually* been quite generally held, though not generally recognized. (NEM 4, 20–21).

#### No. 12. *On the Definition of Logic* [Earlier Draft]

Logic is *formal semiotic*. A sign is something, *A*, which brings something, *B*, its *interpretant* sign, determined or created by it, into the same sort of correspondence (or a lower implied sort) with something, *C*, its *object*, as that in which itself stands to *C*. This definition no more involves any reference to human thought than does the definition of a line as the place within which a particle lies during a lapse of time. It is from this definition that I deduce the principles of logic by mathematical reasoning, and by mathematical reasoning that, I aver, will support criticism of Weierstrassian severity, and that is perfectly evident. The word “formal” in the definition is also defined. (NEM 4, 54).

### Reference

- Charles S. Peirce (1902), “Parts of Carnegie Application” (L 75), published in Carolyn Eisele (ed., 1976),
*The New Elements of Mathematics by Charles S. Peirce*, vol. 4, 13–73. Online.

cc: Cybernetics • Ontolog Forum • Structural Modeling • Systems Science