Quasi-lndexicals and Knowledge Reports

Cognitive Science, 1997

We present a computational analysis of de re, de dicto, and de se belief and knowledge reports. Our analysis solves a problem rst observed by Hector-Neri Castañeda, namely, that the simple rulè (A knows that P) implies P' apparently does not hold if P contains a quasi-indexical. We present a single rule, in the context of a knowledge-representation and reasoning system, that holds for all P, including those containing quasi-indexicals. In so doing, we explore the di erence between reasoning in a public communication language and in a knowledge-representation language, we demonstrate the importance of representing proper names explicitly, and we provide support for the necessity of considering sentences in the context of extended discourse (for example, written narrative) in order to fully capture certain features of their semantics. (This document is SUNY Bu alo Department of Computer Science Technical Report No. 95-49B, as well as SUNY Bu alo Center for Cognitive Science

We present a computational analysis of de re, de dicto, and de se belief and knowledge reports. Our analysis solves a problem first observed by Castaneda, namely, that the simple rule • (A knows that p) implies P , apparently does not hold if P contains a quasi -indicator. We present a single rule, in the context of an AI representation and reasoning system, that holds for all propositions P, including quasi-indexical ones. In so doing, we demonstrate the importance of representing proper names expli citly, and we provide support for the necessity of considering sentences in the context of extended text (e.g., discourse or narrative) in order to fully capture certain features of their semantics.

Aristotelian Society Supplementary Volume

When we report a belief about a particular object, we often implicitly indicate the way the believer thinks of that object. This is why two different beliefs can be reported by 'John believes that Cicero is an excellent writer' and 'John believes that Tully is an excellent writer'. One report can be true and the other false, even though 'Cicero' and 'Tully' refer to the same person. To account for this fact, it is natural to assume that the names 'Cicero' and 'Tully' are somehow associated with different 'modes of presentation' of the individual they both refer to. What is the nature of the link between the referring expression in the 'that'-clause (in my examples, the proper name) and the mode of presentation under which the believer is understood to think of the reference? Is it semantic or pragmatic? Arguably, it is the speaker's choice of a particular referring expression (rather than the expression itself) which, in some contexts, conveys the suggestion that the believer thinks of the referent under this or that mode of presentation. To that extent the link between the proper name and the mode of presentation is 'pragmatic'. Many philosophers take this conclusion to be inconsistent with the thesis of Opacity, according to which the mode of presentation in question affects the truth-conditions of the beliefreport. But this is incorrect. It is possible for something which is pragmatically suggested by the use of some expression to affect the truth-conditional content of the utterance in which the expression occurs. Thus the order of the clauses in 'He took off his clothes and went to bed' (or 'They got married and had many children') pragmatically suggests that one event antedates the other, but this indication, though pragmatic, affects the truth-conditions of the utterance. That this is so is shown,

1984

This thesis is a study in “knowledge ” representation, specifically, how to represent beliefs expressed by sentences containing quasi-indicators. An indicator is a personal or demonstrative pronoun or adverb used to make a strictly demonstrative reference. A quasi-indicator is an expression that occurs within an intentional context and that represents a use of an indicator by another speaker. E.g., if John says, “I am rich”, then if we say, “John believes that he himself is rich”, our use of ‘he himself ’ is quasiindexical. Quasi-indicators pose problems for natural-language question-answering systems, since they cannot be replaced by any co-referential noun phrases without changing the meaning of the embedding sentence. Therefore, the referent of the quasi-indicator must be represented in such a way that no invalid co-referential claims are entailed. I discuss the origin of the problem of quasi-indicators in philosophy of language, and the lack of recognition of its importance by r...

Journal of Pragmatics 39. 2007. 934-959

1998

Journal of Pragmatics, 2008

In this paper, I explore Bach's idea that null appositives, intended as expanded qua-clauses, can resolve the puzzles of belief reports. These puzzles are crucial in understanding the semantics and pragmatics of belief reports and are presented in a section. I propose that Bach's strategy is not only a way of dealing with puzzles, but also an ideal way of dealing with belief reports. I argue that even simple unproblematic cases of belief reports are cases of pragmatic intrusion, involving null appositives, or to use the words of Bach, 'qua-clauses'. The main difference between my pragmatic approach and the one by Salmon (1986) is that this author uses the notion of conversational implicature, whereas I use the notion of pragmatic intrusion and explicature. From my point of view, statements such as ''John believes that Cicero is clever'' and ''John believes that Tully is clever'' have got distinct truth-values. In other words, I claim that belief reports in the default case illuminate the hearer on the mental life of the believer, that includes specific modes of presentation of the referents talked about. Furthermore, while in the other pragmatic approaches, it is mysterious how a mode of presentation is assumed to be the main filter of the believer's mental life, here I provide an explanatory account in terms of relevance, cognitive effects, and processing efforts. The most important part of the paper is devoted to showing that null appositives are required, in the case of belief reports, to explain certain anaphoric effects, which would otherwise be mysterious. My examples show that null appositives are not necessitated at logical form, but only at the level of the explicature, in line with the standard assumptions by Carston and Recanati on pragmatic intrusion. I develop a potentially useful analysis of belief reports by exploiting syntactic and semantic considerations on presuppositional clitics in Romance. #

The Philosophical Review

A speaker's use of a declarative sentence in a context has two effects: it expresses a proposition and represents the speaker as knowing that proposition. This essay is about how to explain the second effect. The standard explanation is act-based. A speaker is represented as knowing because their use of a declarative in a context tokens the act-type of assertion and assertions represent knowledge in what's asserted. I propose a semantic explanation on which declaratives covertly host a "know"-parenthetical. A speaker is thereby represented as knowing the proposition expressed because that is the semantic contribution of the parenthetical. I call this view parentheticalism and contend that it better explains knowledge representation than alternatives. As a consequence of outperforming assertoric explanations, parentheticalism opens the door to eliminating the act-type of assertion from linguistic theorizing.

Journal of Logic, Language and Information, 1996

This paper presents a sound and complete proof system for the first order fragment of Discourse Representation Theory. Since the inferences that human language users draw from the verbal input they receive for the most transcend the capacities of such a system, it can be no more than a basis on which more powerful systems, which are capable of producing those inferences, may then be built. Nevertheless, even within the general setting of first order logic the structure of the “formulas” of DRS-languages, i.e. of the Discourse Representation Structures suggest for the components of such a system inference rules that differ somewhat from those usually found in proof systems for the first order predicate calculus and which are, we believe, more in keeping with inference patterns that are actually employed in common sense reasoning. This is why we have decided to publish the present exercise, in spite of the fact that it is not one for which a great deal of originality could be claimed. In fact, it could be argued that the problem addressed in this paper was solved when Gödel first established the completeness of the system of Principia Mathematica for first order logic. For the DRS-languages we consider here are straightforwardly intertranslatable with standard formulations of the predicate calculus; in fact the translations are so straightforward that any sound and complete proof system for first order logic can be used as a sound and complete proof system for DRSs: simply translate the DRSs into formulas of predicate logic and then proceed as usual. As a matter of fact, this is how one has chosen to proceed in some implementations of DRT, which involve inferencing as well as semantic representation; an example is the Lex system developed jointly by IBM and the University of Tübingen (see in particular (Guenthner et al. 1986)). In the light of the close and simple connections between DRT and standard predicate logic, publication of what will be presented in this paper can be justified only in terms of the special mash we have tried to achieve between the general form and the particular rules of our proof system on the one hand and on the other the distinctive architecture of DRS-like semantic representation. Some additional justification is necessary, however, as there exist a number of other proof systems for first order DRT, some of which have pursued more or less the same aims that have motivated the system presented here. We are explicitly aware of those developed by (Koons 1988), (Saurer 1990), (Sedogbo and Eytan 1987), (Reinhart 1989), (Gabbay and Reyle 1994); perhaps there are others. (Sedogbo and Eytan 1987) is a tableau system, and (Reinhart 1989) and (Gabbay and Reyle 1994) are resolution based, goal directed. These systems may promise particular advantages when it comes to implementing inference engines operating on DRS-like premises. But they do not aim to conform to certain canons of actual inferencing by human interpreters of natural language; and indeed the proof procedures they propose depart quite drastically from what one could plausibly assume to go in the head of such an interpreter. Only (Koons 1988) and (Saurer 1990) are, like our system, inspired by the methods of natural deduction. But there are some differences in the choice of basic rules. In particular both (Koons 1988) and (Saurer 1990) have among their primitive rules the Rule of Reiteration, which permits the copying of a DRS condition from a DRS to any of its sub-DRSs. In our system this is a derived rule (see Section 4 below). We will develop our system in several stages. The necessary intuitions and the formal background are provided in Sections 1 and 2. (The formal definitions can be found also in the first two chapters of (Kamp and Reyle 1993). The first system we present is for a sublanguage of the one defined in Section 2, which differs from the full language in that it lacks identity and disjunction. The core of the paper consists of Section 3, where the proof system for this sublanguage is presented, and Section 5, which extends the system for the full language, including disjunctions (Section 5.1) and identity (Section 5.2) and then establishes soundness and completeness for the full system. Section 4 deals with certain derived inference principles.

Ergo

The present paper argues that there is a knowledge norm for conversational implicature: one may conversationally implicate p only if one knows p. Linguistic data about the cancellation behavior of implicatures and the ways they are challenged and criticized by speakers is presented to support the thesis. The knowledge norm for implicature is then used to present a new consideration in favor of the KK thesis. It is argued that if implicature and assertion have knowledge norms, then assertion requires not only knowledge but iterated knowledge: knowing that you know that you know that . . . you know. Such a condition on permissible assertion is argued to be plausible only if the KK thesis is true.