Online research in philosophy

Classical epistemic logic describes implicit knowledge of agents about facts and knowledge of other agents, based on semantic information. The latter is produced by acts of observation or communication, that are described well by dynamic epistemic logics. What these logics do not describe, however, is how significant information is also produced by acts of inference – and key axioms of the system merely postulate “deductive closure”. In this paper, we take the view that all information is produced by acts, and hence we also need a dynamic logic of inference steps showing what effort on the part of the agent makes a conclusion explicit knowledge. Strong omniscience properties of agents should be seen not as static idealizations, but as the result of dynamic processes that agents engage in. This raises two questions: (a) how to define suitable information states of agents and matching notions of explicit knowledge, (b) how to define natural processes over these states that generate new explicit knowledge. To this end, we extend earlier epistemic “awareness models” into a dynamic system that includes acts of public observation, but also adding and dropping formulas from the currently ‘entertained’ set, we give a completeness theorem, and we show how this dynamics updates explicit knowledge. Similar ideas have been proposed before, but they were restricted to update with factual propositions; our new dynamic system applies to arbitrary formulas. We also extend our approach to multi-agent scenarios where awareness changes may happen privately. Finally, we mention further directions and related approaches.

Elephant 2000 is a proposed programming language good for writing and verifying programs that interact with people (eg. transaction processing) or interact with programs belonging to other organizations (eg. electronic data interchange) 1. Communication inputs and outputs are in an I-O language whose sentences are meaningful speech acts identified in the language as questions, answers, offers, acceptances, declinations, requests, permissions and promises. 2. The correctness of programs is partly defined in terms of proper performance of the speech acts. Answers should be truthful and responsive, and promises should be kept. Sentences of logic expressing these forms of correctness can be generated automatically from the form of the program. 3. Elephant aource programs may not need data structures, because they can refer directly to the past. Thus a program can say that an airline passenger has a reservation if he has made one and hasn't cancelled it. 4. Elephant programs themselves can be represented as sentences of logic. Their extensional properties follow from this representation without an intervening theory of programming or anything like Hoare axioms. 5. Elephant programs that interact non-trivially with the outside world can have both input-output specification, relating the programs inputs and outputs, and accomplishment specifications concerning what the program accomplishes in the world. These concepts are respectively generalizations of the philosophers' illocutionary and perlocutionary speech acts. 6. Programs that engage in commercial transactions assume obligations on behalf of their owners in exchange for obligations assumed by other entities. It may be part of the specification of an Elephant 2000 program that these obligations are exchanged as intended, and this too can be expressed by a logical sentence. 7. Human speech acts involve intelligence. Elephant 2000 is on the borderline of AI, but the article emphasizes the Elephant usages that do not require AI.

SOCREAL 2007: International Workshop on Philosophy and Ethics of Social Reality. Sapporo, Japan, 2007-03-09/10. Session 2: Logical Dynamics of Social Interaction.

In this article, I would like to clarify Austin's thesis that illocutionary acts are essentially conventional and to show, how this idea is connected with his concept of securing uptake. Contrary to what most critics believe, I will show that Austin provides a criterion characterising the nature of all illocutionary acts and allowing to distinguish them from perlocutionary acts.

In this paper, we address several puzzles concerning speech acts,particularly indirect speech acts. We show how a formal semantictheory of discourse interpretation can be used to define speech actsand to avoid murky issues concerning the metaphysics of action. Weprovide a formally precise definition of indirect speech acts, includingthe subclass of so-called conventionalized indirect speech acts. Thisanalysis draws heavily on parallels between phenomena at the speechact level and the lexical level. First, we argue that, just as co-predicationshows that some words can behave linguistically as if they're `simultaneously'of incompatible semantic types, certain speech acts behave this way too.Secondly, as Horn and Bayer (1984) and others have suggested, both thelexicon and speech acts are subject to a principle of blocking or ``preemptionby synonymy'': Conventionalized indirect speech acts can block their`paraphrases' from being interpreted as indirect speech acts, even ifthis interpretation is calculable from Gricean-style principles. Weprovide a formal model of this blocking, and compare it withexisting accounts of lexical blocking.

It is often assumed that Paul Grice, in one way or another, has made an important contribution to the theory of speech acts} Grice, as far as I can see, never expressly addresses Austin’s theory in his published work. He hardly ever uses the speech act terminology of "illocution", "perlocution", etc.2 So what does the more or less implicit Gricean contribution to the theory of speech acts consist in'? There is more than one good answer to this question. I shall concentrate on a particularly influential one, which goes back to Strawson (1964). It says that Austin, in his account of the nature of illocutionary acts, over-emphasized the role of conventions; that Austin went wrong in characterizing illocutionary acts as acts which are essentially conventional. The Gricean contribution to speech act theory, according to the envisaged answer, is twofold, both diagnostic and therapeutic. First, it helps us see where and why Austin went wrong in taking illocutionary acts to be essentially conventional. Second, it suggests an essentially intentional — instead of an essentially conventional- element in illocutionary acts. In his 1964 paper Strawson tried to bring out, as regards the interplay of convention and intention in illocutionary acts, both what can be conceded to Austin and what must be learnt from Grice. Austin (1962: 115) had said that "the performance of an illocutionaiy act involves the securing of uptake". Strawson (1964: 158 ff) interprets Austin as meani_ng to say that the performance of an illocutionary act involves understanding of illocutionary force. Understanding of illocutionary force involves, according to Strawson, grasping a "compleX [speaker’s] intention" (ib.: 160), and it is here, of course, where he brings Gricean ideas into _Austin’s scheme of what the essence of illocution is. He says.

In this paper I try to use the conceptual framework of the speech act theory to clarify a few points regarding the philosophical debate about the existence of negative acts. For this, I start by looking at some of the most popular candidates to this title: failing, omitting, avoiding and refraining. In the second part of my paper I consider some examples of verbal actions and try to investigate how would the property of 'being negative' apply to them, concluding that we could only say about the locutionary contentent of a speech act that it is negative. Since the illocutionary force, which gives the kind of the verbal act performed, cannot be properly called 'negative', there cannot be any 'negative speech acts'. Next, I try to show how this can be applied to such cases. At the end of the paper I propose that an analysis of the situations in which our actions seem to oppose each other should replace the misleading problem of negative acts.

Speech acts have sometimes been considered as unembeddable, for principled reasons. In this paper, I argue that speech acts can be embedded under certain circumstances. In particular, I consider denegation and conjunction of speech acts, quantification into speech acts, conditionalization of speech acts, the embedding of speech acts by verbs like say and wonder, speechact-modifying adverbials like frankly, clauses commenting on speech acts, like certain uses of because-clauses, parentheticals, and appositive relative clauses. A crucial distinction is made between speech acts and speech act potentials, linguistic objects that can be used to perform speech acts when applied in a specific communicative situation. I develop a semantic theory in which speech act potentials are captured as semantic functions that change a world-time index, reflecting the nature of speech acts as events that happen in the world. As index changers, speech act potentials become nearly regular semantic objects, with a proper semantic type on which other semantic objects can operate on. In this way, speech acts (or rather, speech-act potentials) become part of the recursive structure of language.

The Independence postulate links current preferences between called-off acts with current preferences between constant acts. Under the assumption that the chance-events used in compound von Neumann-Morgenstern lotteries are value-neutral, current preferences between these constant acts are linked to current preferences between hypothetical acts, conditioned by those chance events. Under an assumption of stability of preferences over time, current preferences between these hypothetical acts are linked to future preferences between what are then and there constant acts. Here, I show that a failure of Independence with respect to current preferences leads to an inconsistency in sequential decisions. Two called-off acts are constructed such that each is admissible in the same sequential decision and yet one is strictly preferred to the other. This responds to a question regarding admissibility posed by Rabinowicz ([2000] Preference stability and substitution of indifferents: A rejoinder to Seidenfeld, Theory and Decision 48: 311–318 [this issue]).

Abstract: A psychologically plausible analysis of the way we assign illocutionary forces to utterances is formulated using a 'contextualist' analysis of what is said. The account offered makes use of J. L. Austin's distinction between phatic acts (sentence meaning), locutionary acts (contextually determined what is said), illocutionary acts, and perolocutionary acts. In order to avoid the conflation between illocutionary and perlocutionary levels, assertive, directive and commissive illocutionary forces are defined in terms of inferential potential with respect to the common ground. Illocutionary forces are conceived as automatic but optional components of the process of interpretation.