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Foundations of illocutionary logic. (English) Zbl 0577.03011

Cambridge etc.: Cambridge University Press. XI, 227 p. £25.00 (1985).
The authors offer a first general formalization of the (logical) theory of speech acts [J. R. Searle: ”Speech acts”, Cambridge University Press (1969)]. The minimal units of human communication are speech acts of a type called illocutionary acts [J. L. Austin: ”How to do things with words”, Oxford, Claredon Press (1962)]. Illocutionary acts (and forces) are defined as particular cases of performatives - indicative enunciations having the property of realizing the event they describe. J. L. Austin opposed the illocutionary acts, determined by discourse specific rules, to perlocutionary acts whose determination laws have an application area which exceeds by far the discourse. Just as propositional logic studies the properties of all truth functions (e.g. conjunction, implication, negation) independently of the various ways that these are realized in the syntax, so illocutionary logic studies the properties of illocutionary forces (e.g. assertion, conjecture, promise) without worrying about the various ways that are realized in the syntax (”assert”, ”state”, ”claim” and indicative mood - to mention a few for assertion) and independently whether these features translate into other languages.
The study of illocutionary logic is mainly the study of illocutionary forces of utterances. The seven components on the base of which an illocutionary force is defined and described are: illocutionary point, degree of strength of the illocutionary point, mode of achievement, propositional content conditions, preparatory conditions, sincerity conditions, degree of strength of the sincerity conditions.
Chapter 2 in the book defines, in set-theoretical terms, the formal nature of illocutionary forces and their components, explaining them. The general properties of the set of contexts of utterance and of the set of propositions are used.
Since the set-theoretical approach is tedious, Chapter 3 shows how the set of all illocutionary forces can be recursively defined from a few primitive forces, revealing the logical structure of the illocutionary force set. There are (primitive) assertive, commissive, directive, declarative and expressive illocutionary forces. The main operations on (primitive) illocutionary forces are: addition of propositional content conditions, of preparatory conditions, of sincerity conditions, restriction of the mode of achievement of illocutionary point, increasing and decreasing the degrees of strength of the illocutionary point and of the sincerity conditions.
Chapter 4 gives an inductive definition of the necessary and sufficient conditions for the successful performance of illocutionary acts and for the illocutionary commitments. There are also specified the axioms governing the relations of strong and week illocutionary commitment between illocutions.
Chapter 5 explains further four features of illocutionary forces: illocutionary point, direction of fit, degree of strength and sincerity conditions. There are also stated various postulates governing these notions and their relations to speech acts.
Chapter 6 is the central chapter of the book since it presents a systematic and complete exposition of the logical theory. All definitions and independent axioms and postulates of the logical theory are explicitly formulated. The axiomatization, however, is not intended to be complete because there are laws for illocutionary forces that do not follow from these axioms. A more complete axiomatization requiring formal developments of the logic of propositional attitudes and of the modal theory of types of intensional logic will be pursued in a forth-coming book on the model-theoretical semantics of illocutionary acts by Daniel Vanderveken.
Chapters 7 and 8 enumerate a series of philosophically or linguistically significant laws concerning illocutionary forces, speech acts and propositions that follow deductively from axioms.
In Chapter 9, the formal apparatus of illocutionary logic is used to analyze over a hundred English performative or illocutionary verbs.
Appendix 1 gives semantic tableaux for illocutionary entailment of (some) assertive, commissive, directive illocutionary verbs. Together with the contents of Chapter 9, it offers just a sample of the concrete usefulness of the authors’ approach.
The book is addressed to a very wide class of researchers in various fields: language philosophy, language theory, logic, mathematical logic, linguistics, mathematical and computational linguistics, artificial intelligence. The present general axiomatization of speech acts represents a constructive and pioneering achievement, of highest importance in the theory and practice of natural language modelling.
Reviewer: N.Curteanu

MSC:

03B65 Logic of natural languages
03-02 Research exposition (monographs, survey articles) pertaining to mathematical logic and foundations
03C55 Set-theoretic model theory