8/12/2019 Un Diveloppement de La Logique Des Questions.

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Review: [untitled]Author(s): David HarrahSource: The Journal of Symbolic Logic, Vol. 32, No. 4 (Dec., 1967), p. 548Published by: Association for Symbolic LogicStable URL: http://www.jstor.org/stable/2270244.

Accessed: 12/03/2011 13:47

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8/12/2019 Un Diveloppement de La Logique Des Questions.

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548 =REVIEWSComment: The reviewer believes that, if the questioner-datum technique is to be used as the

basis for the logic of questions in a formal language, then, either the language will have to in-clude enough of the usual set theory, syntax, and semantics to provide for questions like Whatis a set of things such that . . . and What is a sentence such that . . . where these questionsare interpreted as presupposing the existence of sets and sentences, or else the language will haveto include ostensible set-theoretical, syntactical, and semantical expressions interpreted by newand relatively complex kinds of semantical rules. The author does not state it in these terms, buthis theory seems to suggest that: (1) understanding a question, and in particular knowing thepresuppositions and ontological commitments of the question, includes knowing the transfor-mational history of the question; (2) the presuppositions and ontological commitments of aquestion can be taken as a function of early stages in the transformational history; and (3) thepresuppositions of a question need not include the result of prefixing an existential quantifierto the datum. The reviewer believes that it would be interesting and worthwhile to see whether aformal semantics for questions, including a formal treatment of presupposition and commitmentof the kind suggested here, could be developed as part of a logic of questions for a formallanguage. DAVID HARRAH

GEROLD STAHL. Un diveloppement de}la logique des questions. Revue philosophique de laFrance et de l'tbranger, vol. 153 (1963), pp. 293-301.

The author presents an analysis of questions similar to the one presented in his XXVIII 259.A higher-order functional system is assumed; certain classes of expressions of this system aredescribed in a meta-system and regarded as questions. E.g., What individual satisfies the func-tion H? is symbolized by '[Hx?]'. Roughly, aperfect answer to [Hx?] is a consistent expressionof the form (Hal.- **-HaJ), (x)(H'x 5 Hx), or (x)'-Hx; a sufficient answer to [Hx?] is (1) atheorem or (2) a consistent sentence which implies a perfect answer which is not a theorem. Thequestion [lx ?] is then the class of its sufficient answers. The author conjectures that all questionsof interest in science and daily life can be treated by his method.

Comment: The reviewer believes that most of the objections to the author's XXVIII 259apply also to this work. Further, as Belnap has pointed out, any sentence (x) -Gx which is notthe negation of a theorem is a sufficient answer to [Hx?], so the identification of questions withclasses of sufficient answers makes the concept of question much too wide. The reviewer believesthat it would be more plausible to drop the consistency requirements on answers and identifyquestions with classes of perfect answers, but that in any case the author's basic idea-ofidentifying questions with classes of answers of some kind-should prove to be a very fruitfulone. DAVID HARRAH

TADEUSZ KUBI&SKI. Przeglqd niekhorych zagadnieh logiki pytahr (A review of some problemsof the logic of questions). Polish, with Russian and English summaries. Stadia logical, vol. 18(1966), pp. 105-137.

The most important attempts to establish a logic of questions (an erotetic or interroga-tive logic, or if need be, semiotic) are reviewed in eight chapters. The author distinguishes in astandard way between erotetic syntax, semantics, and pragmatics. Stress is laid upon thenecessity of studying the problems of erotetic logic on the basis of formalized languages.

The author analyzes four types of formalization of erotetic logic. First Harrah's theory isdiscussed (see especially XXIX 136(2)). The reproduction of the main concepts of Harrah'stheory (which-like Stahl's theory-identifies questions with a kind of propositions) is faithfuland clear. Belnap's (see An analysis of questions, Preliminary report, Technical Memorandum,System Development Corporation, Santa Monica 1963) six categories of questions (three ofthem concerning which-questions, the other three whether-questions ) are then reproducedand some concepts of BeInap's theory compared with some of Harrah's theory. Stahl's theory(see e.g. XXXII 548(1)) identifying questions with classes of answers to those questions is morebriefly mentioned and a problem is discussed which is implied by (not formulated in) Stahl'stheory and concerns the role of certain constant functors and functorial variables. A connectionbetween this problem and the protothetic of Legniewski is stated.

The fourth type of formalization of erotetic logic is represented by the work of the authorhimself (see e.g. his earlier paper: Pewne pojkcia konsekwencji slabycb i ich zastosowania (Some