Haack On Fuzzy Logic Essay -- Haack Philosophy Philosophical Essays

Haack On Fuzzy Logic ABSTRACT: Much of the progress in modern logic beyond Aristotle is due to the invention of a precise and powerful formalism, and this is why Haack is reluctant to weaken it. What motivates her to regard deviant and fuzzy logic as extensions rather than rivals of classical logic is its demonstrated capacity for refinement and progress. Thus she sharply distinguishes between a logic dealing with fuzzy concepts (she accepts), and one which is itself fuzzy, i.e., where "true" and "false" cease to be precise concepts (she rejects). While it is often more convenient to retain as much as possible of classical logic because of its simplicity and familiarity, there is nothing in the hermeneutical view of logic to render it immune from revision. Yet to treat logic as a canon of interpretation conflicts with Haack's idea of what logic is and does. L.A. Zadeh who introduced the term "fuzzy logic" reserves it for the result of a second stage of fuzzification, motivated by the idea that "true" and "false" are themselves vague: a family of systems in which the indenumerably many values of truth values of the base logic are superseded by denumerably many fuzzy truth values, true, false, very true, fairly true, not very true, etc. For fuzzy logic, Zadeh tells us, such traditional concerns as approximation, proof procedures, etc. are "peripheral" because fuzzy logic is not just logic of fuzzy concepts, but is logic, which is itself fuzzy. (1) Susan Haack criticizes Zadeh on the grounds that fuzzy logic is not well motivated, since truth does not come in degrees. Inevitably some will protest that fuzzy logic is working, and so that her distaste for it can only be an expression of a Fregean prejudice. But she claims that i... ...ic Justification of a Conceptual Notation," 1882/translation by Bynum T. Ward in Gottlob Frege: Conceptual Notation and Related Articles, Oxford: Claredon Press 1982, p. 86. (6) F.S.C. Schiller, Formal Logic, A Scientific and Social Problem, London: Macmillan 1912, p. 8. (7) Haack, p. 233. (8) R. Carnap, Logical Foundations of Probability, Chicago: Chicago University Press 1950. (9) Haack, p. 233. (10) ibid. p. 234. (11) L.A. Zadeh and R.E. Bellman, "Local and Fuzzy Logics," in M. Dunn and G. Epstein, Eds, Modern Uses of Multiple-Value Logics, Dordrecht: Reidel 1977, pp. 106-107. (12) Haack, p. 236. (13) ibid. p. 237. (14) L.A. Zadeh, "A Fuzzy-Algorithm Approach to the Definition of Complex or Imprecise Concepts," International Journal of Man-Machine Studies 1976 vol.8 p.269n. (15) Haack, p.238. (16) ibid. p. 240. (17) ibid. p. 242.