Editing Charles Sanders Peirce (section)

==== Logic as philosophical ====
Peirce regarded logic ''per se'' as a division of philosophy, as a normative science based on esthetics and ethics, as more basic than metaphysics,<ref name="FRL">Peirce (1899 MS), "F.R.L." [First Rule of Logic], ''Collected Papers of Charles Sanders Peirce'', 1.135–140, [https://web.archive.org/web/20120106071421/http://www.princeton.edu/~batke/peirce/frl_99.htm Eprint]</ref> and as "the art of devising methods of research".<ref name="ars">Peirce (1882), "Introductory Lecture on the Study of Logic" delivered September 1882, ''Johns Hopkins University Circulars'', v. 2, n. 19, pp. [https://books.google.com/books?id=E0YFAAAAQAAJ&pg=PA11&dq=%22art+of+devising+methods+of+research%22 11–12] (via Google), November 1882. Reprinted (''The Essential Peirce'', 1:210–214; ''Writings of Charles S. Peirce'', 4:378–382; ''Collected Papers of Charles Sanders Peirce'', 7.59–76). The definition of logic quoted by Peirce is by [[Peter of Spain (author)|Peter of Spain]].</ref> More generally, as inference, "logic is rooted in the social principle", since inference depends on a standpoint that, in a sense, is unlimited.<ref>Peirce (1878), "The Doctrine of Chances", ''Popular Science Monthly'', v. 12, pp. 604–615 (CP 2.645–668, ''Writings of Charles S. Peirce'', 3:276–290, ''The Essential Peirce'', 1:142–154). {{quote|...&nbsp;death makes the number of our risks, the number of our inferences, finite, and so makes their mean result uncertain. The very idea of probability and of reasoning rests on the assumption that this number is indefinitely great. ... logicality inexorably requires that our interests shall ''not'' be limited. ... Logic is rooted in the social principle.}}</ref> Peirce called (with no sense of deprecation) "mathematics of logic" much of the kind of thing which, in current research and applications, is called simply "logic". He was productive in both (philosophical) logic and logic's mathematics, which were connected deeply in his work and thought.

Peirce argued that logic is formal semiotic: the formal study of signs in the broadest sense, not only signs that are artificial, linguistic, or symbolic, but also signs that are semblances or are indexical such as reactions. Peirce held that "all this universe is perfused with signs, if it is not composed exclusively of signs",<ref>Peirce, ''Collected Papers of Charles Sanders Peirce'', 5.448 footnote, from "The Basis of Pragmaticism" in 1906.</ref> along with their representational and inferential relations. He argued that, since all thought takes time, all thought is in signs<ref name="QFM">Peirce, (1868), "Questions concerning certain Faculties claimed for Man", ''Journal of Speculative Philosophy'' v. 2, n. 2, [https://books.google.com/books?id=YHkqP2JHJ_IC&pg=RA1-PA103 pp. 103–114]. On thought in signs, see p. 112. Reprinted ''Collected Papers of Charles Sanders Peirce'', 5.213–263 (on thought in signs, see 253), ''Writings of Charles S. Peirce'', 2:193–211, ''The Essential Peirce'', 2:11–27. ''Arisbe'' [http://www.cspeirce.com/menu/library/bycsp/question/qu-frame.htm Eprint] {{Webarchive|url=https://web.archive.org/web/20071014064210/http://cspeirce.com/menu/library/bycsp/question/qu-frame.htm |date=2007-10-14  }}.</ref> and sign processes ("semiosis") such as the inquiry process. He [[Classification of the sciences (Peirce)|divided]] logic into: (1) speculative grammar, or stechiology, on how signs can be meaningful and, in relation to that, what kinds of signs there are, how they combine, and how some embody or incorporate others; (2) logical critic, or logic proper, on the modes of inference; and (3) speculative or [[universal rhetoric]], or methodeutic,<ref name="rhetoric"/> the philosophical theory of inquiry, including pragmatism.