Daniel Vanderveken

Formal Pragmatics of Non Literal Meaning

In the past decades, there has been much progress in the formal Semantics of ordinary language. Logicians, linguists and philosophers have extensively used logical formalisms in order to interpret directly or after translation important fragments of actual natural languages. They have thereby contributed to the foundations of the theory of sentence meaning. In formal Semantics, speaker meaning is reduced to sentence meaning: one assumes that speakers only mean what they say. Thus, formal semantics is a theory of literal meaning. However, in ordinary conversations, the speaker’s meaning is often different from the sentence meaning. First, the primary illocutionary act that the speaker attempts to perform is different from the literal speech act expressed by the uttered sentence in the cases of metaphor, irony and indirect speech acts. Whenever the speaker indirectly requests the hearer to pass the salt by asking “Can you pass the salt?”, the primary speech act of the utterance is the indirect request and not the literal question about the hearer’s abilities. Second, the speaker means to perform secondary non literal illocutionary acts in the cases of conversational implicatures. By saying “If you are nice, I will give you something” the speaker can imply conversationally that he will not give anything to the hearer if he is not nice. In such a case, he makes a secondary non literal assertion in addition to the primary conditional promise. The speaker’s capacity to make and understand non literal speech acts is clearly part of his linguistic competence. But it exceeds the capacity of understanding the sentence meaning.

Speech Acts and Illocutionary Logic

1. Illocutionary acts and illocutionary logic. The minimal units of human communication are speech acts of a type called illocutionary acts.1 Some examples of these are statements, questions, commands, promises, and apologies. Whenever a speaker utters a sentence in an appropriate context with certain intentions, he performs one or more illocutionary acts. In general an illocutionary act consists of an illocutionary force F and a propositional content P . For example, the two utterances “You will leave the room” and “Leave the room!” have the same propositional content, namely that you will leave the room; but characteristically the first of these has the illocutionary force of a prediction and the second has the illocutionary force of an order. Similarly, the two utterances “Are you going to the movies?” and “When will you see John?” both characteristically have the illocutionary force of questions but have different propositional contents. Illocutionary logic is the

Attempt, Success and Action Generation: A Logical Study of Intentional Action

Contemporary philosophers have broadly studied intentional actions that agents attempt to perform in the world. However, logicians of action have tended to neglect the intentionality proper to human action. I will present here the basic principles and laws of a logic of individual action where intentional actions are primary as in contemporary philosophy of action. In my view, any action that an agent performs unintentionally could in principle have been attempted. Moreover any unintentional action of an agent is an effect of intentional actions of that agent. So my logic of action contains a theory of attempt and of action generation. As Belnap pointed out, action, branching time and historic modalities are logically related. There is the liberty of voluntary action. I will then work out a logic of action that is compatible with indeterminism.

Illocutionary Logic and Self-Defeating Speech Acts

Illocutionary logic is the branch of philosophical logic that is concerned with the study of the illocutionary acts (assertions, questions, requests, promises, orders, declarations…) that are performed by the utterance of sentences of natural or formal languages. The analytic philosophers (especially J. L. Austin and J. R. Searle) have shown the philosophical importance of a logical analysis of the forms of such speech acts. Illocutionary force is indeed one essential and irreducible component of the sense of a sentence of a natural language. One cannot understand the sense of a sentence without understanding that its literal utterance in a given context of use constitutes the performance of illocutionary acts of such and such forms. Thus for example, in order to understand the sense of the English sentence (1) “Are you going to the theater tonight?” one must not only understand that in a context of use where this sentence is uttered literally, the speaker expresses a proposition that is true in the world of utterance iff the hearer in that world goes to a theater the evening of the day of the utterance. One must also understand that this utterance in that context of use constitutes the asking of a question.

Speech acts in a connected discourse: a computational representation based on conceptual graph theory

Abstract The purpose of this research is to study how to represent speech acts within texts. We consider that conversations are temporal sequences of connected illocutionary acts which result in discourses. Using Searle and Vanderveken illocutionary logic, we propose an extension of Sowas conceptual graph theory that enables us to represent the conceptual structure of conversations and to model the speech acts that are the basic units of communication in conversations. This approach enables us to represent explicitly several time coordinate systems which are underlying the use of temporal knowledge in discourses: the locutors’ temporal perspective; the localization of temporal situations (processes, events, states etc.); the utterance perspectives of agents who utter sentences. Within an utterance perspective, speakers use sentences with the intention to perform illocutionary acts whose propositional content is represented by conceptual graphs. Our approach also enables us to model several linguistic phe...

Agent Communication Language: Toward a Semantics Based on Success, Satisfaction, and Recursion

Searle and Vandervekens model of speech acts is undoubtedly an adequate model for the design of communicating agents because it offers a rich theory which can give important properties of protocols that we can formalize properly. We examine this theory by focusing on the two fundamentals notions, success and satisfaction, which represent a systematic, unified account of both the truth and the success conditional aspects. Then, we propose an adequate formalism-the situation calculus-for representing these two notions (in a recursive way) in the context of agent communication language. The resulting framework is finally used for (1) the analysis and interpretation of speech acts; (2) the semantics and descriptions of agent communication languages.

Towards a Formal Pragmatics of Discourse

Could we enrich speech-act theory to deal with discourse? Wittgenstein and Searle pointed out difficulties. Most conversations lack a conversational purpose, they require collective intentionality, their background is indefinitely open, irrelevant and infelicitous utterances do not prevent conversations to continue, etc. Like Wittgenstein and Searle I am sceptic about the possibility of a general theory of all kinds of language-games. In my view, the single primary purpose of discourse pragmatics is to analyse the structure and dynamics of language-games whose type is provided with an internal conversational goal. Such games are indispensable to any kind of discourse. They have a descriptive, deliberative, declaratory or expressive conversational goal corresponding to a possible direction of fit between words and things. Logic can analyse felicity-conditions of such language-games because they are conducted according to systems of constitutive rules. Speakers often speak non-literally or non-seriously. The real units of conversation are therefore attempted illocutions whether literal, serious or not. I will show how to construct speaker-meaning from sentence-meaning, conversational background and conversational maxims. I agree with Montague that we need the resources of formalisms (proof, model- and game-theories) and of mathematical and philosophical logic in pragmatics. I will explain how to further develop propositional and illocutionary logics, the logic of attitudes and of action in order to characterize our ability to converse. I will also compare my approach to others (Austin, Belnap, Grice, Montague, Searle, Sperber and Wilson, Kamp, Wittgenstein) as regards hypotheses, methodology and other issues.

A New Formulation of the Logic of Propositions

In the philosophy of language and mind, the abstract entities called propositions have a double nature. On one hand, they are units of sense of a fundamental logical type which are expressed by the use of sentences. All propositions represent states of affairs and are true or false depending on how things are in the actual world. On the other hand, propositions are also the contents of conceptual thoughts that we, human beings, have in mind whenever we think, speak or write. As ordinary language philosophers have shown, the primary units of meaning in the use and comprehension of language are speech acts such as assertions, promises and requests which consist of an illocutionary force F with a propositional content P. Moreover, many of our mental states are attitudes like beliefs, intentions and desires which consist of a psychological mode m with a propositional content P. Like illocutionary acts, such attitudes are conceptual thoughts whose contents represent states of affairs.

Formal semantics for propositional attitudes

Contemporary logic is confined to a few paradigmatic attitudes such as belief, knowledge, desire and intention. My purpose is to present a general model-theoretical semantics of propositional attitudes of any cognitive or volitive mode. In my view, one can recursively define the set of all psychological modes of attitudes. As Descartes anticipated, the two primitive modes are those of belief and desire. Complex modes are obtained by adding to primitive modes special cognitive and volitive ways or special propositional content or preparatory conditions. According to standard logic of attitudes (Hintikka), human agents are either perfectly rational or totally irrational. I will proceed to a finer analysis of propositional attitudes that accounts for our imperfect but minimal rationality. For that purpose I will use a non standard predicative logic according to which propositions with the same truth conditions can have different cognitive values and I will explicate subjective in addition to objective possibilities. Next I will enumerate valid laws of my general logic of propositional attitudes. At the end I will state principles according to which minimally rational agents dynamically revise attitudes of any mode.

Propositional Identity, Truth According to Predication and Strong Implication

In contemporary philosophy of language, mind and action, propositions are not only Senses of sentences with truth conditions but also contents of conceptual thoughts like illocutionary acts and attitudes that human agents perform and express. It is quite clear that propositions with the same truth conditions are not the senses of the same sentences, just as they are not the contents of the same thoughts. To account for that fact, the logic of propositions according to predication advocates finer criteria of propositional identity than logical equivalence and requires of competent speakers less than perfect rationality. Unlike classical logic it analyzes the structure of constituents of propositions. The logic is predicative in the very general sense that it analyzes the type of propositions by mainly taking into consideration the acts of predication that we make in expressing and understanding them. Predicative logic distinguishes strictly equivalent propositions whose expression requires different acts of predication or whose truth conditions are understood in different ways. It also explicates a new relation of strong implication between propositions much finer than strict implication and important for the analysis of psychological and illocutionary commitments. The main purpose of this work is to present and enrich the logic of propositions according to predication by analyzing elementary propositions that predicate all kinds of attributes (extensional or not) as well as modal propositions according to which it is necessary, possible or contingent that things are so and so. I will first explain how predicative logic analyzes the structure of constituents and truth conditions of propositions expressible in the modal predicate calculus without quantifiers. The ideal object language of my logic is a natural extension of that of the minimal logic of propositions. Next I will define the structure of a model and I will formulate an axiomatic system. At the end I will enumerate important valid laws. The present work on propositional logic is part of my next book Propositions, Truth and Thought which formulates a more general logic of propositions according to predication analyzing also generalization, ramified time, historic modalities as well as action and attitudes.