Stephen Read

In this book, Stephen Read sets out to rescue logic from its undeserved reputation as an inflexible, dogmatic discipline by demonstrating that its technicalities and processes are founded on assumptions which are themselves amenable to philosophical investigation. He examines the fundamental principles of consequence, logical truth and correct inference within the context of logic, and shows that the principles by which we delineate consequences are themselves not guaranteed free from error. Central to the notion of truth is the beguiling issue of paradox. Its philosophical value, Read shows, lies in exposing the invalid assumption on which the paradox is built. Thinking About Logic also discusses logical puzzles which introduce questions relating to language, the world, and their relationship.

Bradwardine’s solution to the the logical paradoxes depends on the idea that every sentence signifies many things, and its truth depends on things’ being wholly as it signifies. This idea is underpinned by his claim that a sentence signifies everything that follows from what it signifies. But the idea that signification is closed under entailment appears too strong, just as logical omniscience is unacceptable in the logic of knowledge. What is needed is a more restricted closure principle. A clue can be found in speech act pluralism, whereby indirect speech reports are closed under intersubstitutivity of co-referential terms. The conclusion is that solving the semantic paradoxes does not require revision of logic, thus saving logic from paradox

Gabriel Nuchelmans, Dilemmatic arguments. Towards a history of their logic and rhetoric. Amsterdam, New York, Oxford, Tokyo:North-Holland, 1991. 152pp. No price stated Francis P. Dinneen, Peter of Spain:language in dispute. Amsterdam and Philadelphia: John Benjamins Publishing Company, 1990. xxxix + 271 pp. Hfl. 110/$58.00 Charles H. Manekin, The logic of Gersonides. A translation of Sefer ha-heqqesh ha-yashar of Rabbi Levi ben Gershom with introduction, commentary and analytical glossary. Dordrecht, Boston and London:Kluwer Academic Publishers, 1992. xii + 341 pp. £61.00 F. P. Ramsey, Notes on philosophy, probability and mathematics. Edited by Maria Carla Galavotti. Naples:Bibliopolis, 1991 [published 1992]. 349 pp. No price stated Thomas Drucker, Perspectives on the History of Mathematical Logic. Boston, Basel, Berlin; Birkhäuser, 1991. xxiii 4- 195 pp. 108 SFr./128 DM J.P. Cleave, A study of logics. Oxford:Clarendon Press, 1991. xiii + 417 pp. £65.00 Hartry Field, Realism, mathematics and modality. Oxford and Cambridge :Blackwell, 1989. viii + 290 pp. £14.95 T.E. Forster, Set theory with a universal set, exploring an untyped universe. Oxford:Clarendon Press, 1992. viii + 152 pp., £25.00 Mark Sainsbury, Logical forms:an introduction to philosophical logic. Cambridge, Mass, and Oxford: Basil Blackwell Publishers, 1991. viii + 398 pp. £40.00, £11.95 L.C. Burns, Vagueness. An investigation into natural languages and the sorites paradox. Dordrecht, Boston and London:Kluwer, 1991. xii + 202 pp. dollar;130.00/£74.00/Dfl 130 Douglas Walton, Slippery slope arguments. Oxford:The Clarendon Press, 1992. xi + 296 pp. £35.00 Bas Van Fraassen, Quantum mechanics. An empiricist view. Oxford:Clarendon Press, 1991. xvi + 541 pp. £50.00 /£17.50 R. Giuntini, Quantum logic and hidden variables. Mannheim, Vienna and Zürich:BI-Wissenschaf ts-verlag, 1991. x + 184 pp. No price stated W. Spohn, B.C. Van Fraassn And B. Skyrms, Existence and explanation:essays presented in honor of Karel Lambert. Dordrect, Boston and London: Kluwer Academic Publishers, 1991. xii 4- 243 pp. £56.00 Michele Di Francesco, Il realismo analitico. Logica, ontologia e significato nel primo Russell Milan:Guerini, 1991. 269 pp. 30,000 Lire Kenneth Blackwell and Carl Spadont, A detailed catalogue of the second archives of Bertrand Russell. Bristol:Thoemmes Press, 1992. xxvi + 433 pp. £60.00

t is often suggested that truth-preservation is insufficient for logical consequence, and that consequence needs to satisfy a further condition of relevance. Premises and conclusion in a valid consequence must be relevant to one another, and truth-preservation is too coarse-grained a notion to guarantee that. Thus logical consequence is the intersection of truth-preservation and relevance. This situation has the absurd consequence that one might concede that the conclusion of an argument was true (since the argument had true premises and was truth-preserving); yet should refuse to infer the conclusion from the premises, in the absence of demonstration of the relevance of the premises to the conclusion. The error lies in giving insufficient attention to the notion of truth-preservation. Relevance is no separable ingredient in the analysis of logical consequence, but a necessary condition of it. What we show is that if an argument really is truth-preserving, then that in itself is enough to show that the premises are (logically) relevant to the conclusion.

Thomas Bradwardine's solution to the semantic paradoxes, presented in his Insolubilia written in Oxford in the early 1320s, turns on two main principles: that a proposition is true only if things are wholly as it signifies; and that signification is closed under consequence. After exploring the background in Walter Burley's account of the signification of propositions, the question is considered of the extent to which Bradwardine's theory is compatible with the distribution of truth over conjunction, disjunction, negation and the conditional.

Intentional verbs create three different problems: problems of non-existence, of indeterminacy, and of failure of substitutivity. Meinongians tackle the first problem by recognizing non-existent objects; so too did many medieval logicians. Meinongians and the medievals approach the problem of indeterminacy differently, the former diagnosing an ellipsis for a propositional complement, the latter applying their theory directly to non-propositional complements. The evidence seems to favour the Meinongian approach. Faced with the third problem, Ockham argued bluntly for substitutivity when the intentional complement is non-propositional; Buridan developed a novel way of resisting substitutivity. Ockham's approach is closer to the Meinongian analysis of these cases; Buridan's seems to raise difficulties for a referential semantics. The comparision between the Meinongian and medieval approaches helps to bring out merits and potential pitfalls of each.

This book presents the very latest research on the medieval use of sophisms in logical and grammatical investigation by twenty-three of the leading experts in Europe and beyond. Important insights into the genre of sophismatic treatises have been gained only very recently, and the organisation of the European Symposium on this topic in 1990 led to a concentration of research and evaluation of insights. The papers are divided into three groups: one covers textual study and analysis of the role of sophisms in the medieval curriculum; another deals with grammatical sophisms; and the third covers particular logical sophisms, from 'Man is the worthiest of creatures' and problems in the theory of reference to the Liar paradox and the work of William of Ockham.

In his article "Verdades antiguas y modernas" (in the same issue, pp. 207-27), David Miller criticised Thomas Bradwardine’s theory of truth and signification and my defence of Bradwardine’s application of it to the semantic paradoxes. Much of Miller’s criticism is sympathetic and helpful in gaining a better understanding of the relationship between Bradwardine’s proposed solution to the paradoxes and Alfred Tarski’s. But some of Miller’s criticisms betray a misunderstanding of crucial aspects of Bradwardine’s account of truth and signification.

Inferentialism claims that expressions are meaningful by virtue of rules governing their use. In particular, logical expressions are autonomous if given meaning by their introduction-rules, rules specifying the grounds for assertion of propositions containing them. If the elimination-rules do no more, and no less, than is justified by the introduction-rules, the rules satisfy what Prawitz, following Lorenzen, called an inversion principle. This connection between rules leads to a general form of elimination-rule, and when the rules have this form, they may be said to exhibit “general-elimination” harmony. Ge-harmony ensures that the meaning of a logical expression is clearly visible in its I-rule, and that the I- and E-rules are coherent, in encapsulating the same meaning. However, it does not ensure that the resulting logical system is normalizable, nor that it satisfies the conservative extension property, nor that it is consistent. Thus harmony should not be identified with any of these notions.

In recent years, speech-act theory has mooted the possibility that one utterance can signify a number of different things. This pluralist conception of signification lies at the heart of Thomas Bradwardine’s solution to the insolubles, logical puzzles such as the semantic paradoxes, presented in Oxford in the early 1320s. His leading assumption was that signification is closed under consequence, that is, that a proposition signifies everything which follows from what it signifies. Then any proposition signifying its own falsity, he showed, also signifies its own truth and so, since it signifies things which cannot both obtain, it is simply false. Bradwardine himself, and his contemporaries, did not elaborate this pluralist theory, or say much in its defence. It can be shown to accord closely, however, with the prevailing conception of logical consequence in England in the fourteenth century. Recent pluralist theories of signification, such as Grice’s, also endorse Bradwardine’s closure postulate as a plausible constraint on signification, and so his analysis of the semantic paradoxes is seen to be both well-grounded and plausible.

The correspondence theory of truth has experienced something of a revival recently in the form of the Truthmaker Axiom: whatever is true, something makes it true. We consider various postulates which have been proposed to characterize truthmaking, in particular, the Disjunction Thesis (DT), that whatever makes a disjunction true must make one or other disjunct true. In conjunction with certain other assumptions, DT leads to triviality. We show that there are elaborations of truthmaking on which DT holds (which must therefore take steps to avoid the triviality); but that there are more plausible accounts of truthmaking on which DT fails.

MEDIEVAL LOGICCARLOS A. DUFOUR, Die Lehre der Proprietates Terminorum. Sinn und Referenz in mittelalterlicher Logik. München, Hamden, Wien: Philosophia, 1989. 312 pp. 148 DM.NORMAN KRETZMANN and BARBARA ENSIGN KRETZMANN The Sophismata of Richard Kilvington. Oxford: Published for the British Academy by Oxford University Press, 1990. xx + 156 pp. £27.50.LOGIC AND MATHEMATICSSOULEYMANE BACHIR DIAGNE, Boole. Paris: Editions Belin, 1989. 262pp. 75 Ffr.M.-M. TOEPELL, Über die Entstehung von David Hilberts “Grundlagen der Geometrie”. Göttingen: Vandenhoeck und Ruprecht, 1986. vii + 293 pp. 82 DM.VOLKER PECKHAUS, Hilbertprogramm und Kritische Philosophie. Das Göttinger Model1 interdisziplinarer Zusammenärbeit zwischen Mathematik und Philosophie. Gottingen: Vandenhoeck und Ruprecht, 1990. vi + 291 pp. 78 DM.E. WELTI, Die Philosophie des Strikten Finitismus, Entwicklungstheoretische und mathematische Untersuchungen iiber Unendlichkeitsbegriffe in Ideengeschichte und Mathematik, Bern, Frankfurt am Main und New York: Peter Lang, 1986. xxix + 652pp. $79.90.Philosophy of logicMARK A. NOTTURNO, Perspectives on psychlogism. Leiden, New York, Copenhagen and Cologne: E. J. Brill, 1989. viii + 504 pp. 225 Dfl/$112.50.ROBERT N. MCLAUGHLIN, On the logic of ordinary conditionals. Albany: State University of New York Press, 1990. xvii + 202 pp. $54.50 /$17.95.JAAKKO HINTIKKA and MERRILL HINTIKKA, The logic of epistemology and the epistemology of logic: selected essays. Dordrecht, Boston and London: Kluwer Academic Publishers, 1989.J. NORMAN and R. SYLVAN, Directions in relevant logic. Foreword by N. D. Belnap. Dordrecht, Boston and London: Kluwer Academic Publishers, 1989. xii + 453 pp. £72.00.LOGIC AND LANGUAGEC. J. F. WILLIAMS, What is identity? Oxford: Clarendon Press, 1989. xx + 207 pp. £25.00.GREGORY MCCULLOCH, The game of the name. Oxford: Oxford University Press, 1989. xvi + 320pp. £30.00, £9.95.GRAEME FORBES, Languages of possibility. Oxford: Basil Blackwell, 1989. x + 181 pp. £27.50.