Cf: C.S. Peirce • On the Definition of 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).
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 ( https://arisbe.sitehost.iu.edu/menu/library/bycsp/L75/l75.htm