My chief aim has been to convey the thought that the application of model theoretic techniques to natural languages needn't force a distortion of intentional phenomena. I hope that at least I have succeeded in accomplishing this.
Early attempts at combining multiple inheritance with nonmonotonic reasoning were based on straightforward extensions of tree-structured inheritance systems, and were theoretically unsound. In The Mathcmat~'cs of Inheritance Systcrns, or TMOIS, Touretzky described two problems these systems cannot handle: reasoning in the presence of true but redundant assertions, and coping with ambiguity. TMOIS provided a definition and analysis of a theoretically sound multiple inheritance system, accom-.
We identify a class of paradoxes that is neither set-theoretical nor semantical, but that seems to depend on intensionality. In particular, these paradoxes arise out of plausible properties of propositional attitudes and their objects. We try to explain why logicians have neglected these paradoxes, and to show that, like the Russell Paradox and the direct discourse Liar Paradox, these intensional paradoxes are recalcitrant and challenge logical analysis. Indeed, when we take these paradoxes seriously, we may need to rethink the commonly (...) accepted methods for dealing with the logical paradoxes. (shrink)
We relate the theory of presupposition accommodation to a computational framework for reasoning in conversation. We understand presuppositions as private commitments the speaker makes in using an utterance but expects the listener to recognize based on mutual information. On this understanding, the conversation can move forward not just through the positive effects of interlocutors’ utterances but also from the retrospective insight interlocutors gain about one anothers’ mental states from observing what they do. Our title, ENLIGHTENED UPDATE, highlights such cases. Our (...) approach fleshes out two key principles: that interpretation is a form of intention recognition; and that intentions are complex informational structures, which specify commitments to conditions and to outcomes as well as to actions. We present a formalization and implementation of these principles for a simple conversational agent, and draw on this case study to argue that pragmatic reasoning is holistic in character, continuous with common-sense reasoning about collaborative activities, and most effectively characterized by associating specific, reliable interpretive constraints directly with grammatical forms. In showing how to make such claims precise and to develop theories that respect them, we illustrate the general place of computation in the cognitive science of language. (shrink)
This paper proposes a formalization of ability that is motivated in part by linguistic considerations and by the philosophical literature in action theory and the logic of ability, but that is also meant to match well with planning formalisms, and so to provide an account of the role of ability in practical reasoning. Some of the philosophical literature concerning ability, and in particular [Austin, 1956], suggests that some ways of talking about ability are context-dependent. I propose a way of formalizing (...) this dependency. (shrink)
This paper develops a general approach to contextual reasoning in natural language processing. Drawing on the view of natural language interpretation as abduction (Hobbs et al., 1993), we propose that interpretation provides an explanation of how an utterance creates a new discourse context in which its interpreted content is both true and promi- nent. Our framework uses dynamic theories of semantics and pragmatics, formal theories of context, and models of attentional state. We describe and illustrate a Prolog implementation.
The first amounts, roughly, to "It is necessarily the case that any President of the U.S. is a citizen of the U.S." But the second says, "the person who in fact is the President of the U.S, has the property of necessarily being a citizen of the U.S," Thus, while (2) is clearly true, it would be reasonable to consider (3) false.
It has been claimed that counterpart theory cannot support a theory of actuality without rendering obviously invalid formulas valid or obviously valid formulas invalid. We argue that these claims are not based on logical flaws of counterpart theory itself, but point to the lack of appropriate devices in first-order logic for “remembering” the values of variables. We formulate a mildly dynamic version of first-order logic with appropriate memory devices and show how to base a version of counterpart theory with actuality (...) on this. This theory is, in special cases, equivalent to modal first-order logic with actuality, and apparently does not suffer from the logical flaws that have been mentioned in the literature. (shrink)
The psychological orientation treats semantics as a matter of idealized computation over symbolic structures, and semantic relations like denotation as relations between linguistic expressions and these structures. I argue that results similar to Gödel's incompleteness theorems and Tarski's theorem on truth create foundational difficulties for this view of semantics.
The interpretation of indirect discourse is one of the most persistent and pervasive themes in post-Fregean semantics. Since Frege we have managed to learn a good deal about the workings of various technical approaches to indirect discourse, but fundamental philosophical issues have remained unresolved.
rich domain involves an intricate mixture of strict and defeasible information. The importance of representing defeasible information in an inheritance system has been widely recognized, but it is not enough for a sys-.
A propositional system of modal logic is second-order if it contains quantiﬁers ∀p and ∃p, which, in the standard interpretation, are construed as ranging over sets of possible worlds (propositions). Most second-order systems of modal logic are highly intractable; for instance, when augmented with propositional quantiﬁers, K, B, T, K4 and S4 all become eﬀectively equivalent to full second-order logic. An exception is S5, which, being interpretable in monadic second-order logic, is decidable.
Most human thinking is thoroughly informed by context but, until recently, theories of reasoning have concentrated on abstract rules and generalities that make no reference to this crucial factor. _Perspectives on Contexts_ brings together essays from leading cognitive scientists to forge a vigorous interdisciplinary understanding of the contextual phenomenon. Applicable to human and machine cognition in philosophy, artificial intelligence, and psychology, this volume is essential to the current renaissance in thinking about context.
I argue that a counterexample proposed by donald nute shows only that past tenses involve indexical restriction to a limited domain of times. The purpose of this note is to defend the thesis that there is a single conditional connective figuring in both indicative and 'had'--'would' connectives, And that the differences in logical form between the two sorts of english conditional expressions have to do with tense.
This is part of a larger project that is motivated in part by linguistic considerations and by the philosophical literature in action theory and the logic of ability, but that is also meant to suggest ways in which planning formalisms could be modified to provide an account of the role of ability in planning and practical reasoning.
“Philosophy of action” is a recognized specialty in contemporary philosophy, and the literature on action is fairly extensive: see, for instance, (Care & Landesman 1968; Goldman 1970; Hornsby 1980). The relation of actions to their effects is formulated most clearly in the more specialized literature on the logic of action; see (Belnap & Perloff 1988; Chellas 1992; Czelakowski 1996; Segerberg 1982).
Possible worlds semantics for conditionals leave open the problem of how to construct models for realistic domains. In this paper, we show how to adapt logics of action and change such as John McCarthy’s Situation Calculus to conditional logics. We illustrate the idea by presenting models for conditionals whose antecedents combine a declarative condition with a hypothetical action.
We use a dynamic, context-sensitive approach to abductive interpretation to describe coordinated processes of understanding, generation and accommodation in dialogue. The agent updates the dialogue uniformly for its own and its interlocutors’ utterances, by accommodating a new context, inferred abductively, in which utterance content is both true and prominent. The generator plans natural and comprehensible utterances by exploiting the same abductive preferences used in understanding. We illustrate our approach by formalizing and implementing some interactions between information structure and the form (...) of referring expressions. (shrink)
From its beginnings in Aristotle, logic was intended to account not only for reasoning that is theoretical (or conclusion-oriented), but for reasoning that is practical (or actionoriented). However, despite an interest in the topic that continues to the present, the practical side of reasoning has remained broadly speculative. At least in some domains (mathematics, in particular), there are well developed proof-theoretic and semantic theories that yield quite detailed models of correct reasoning, and these models are useful for both theoretical and (...) practical purposes. In contrast, the logical work on practical reasoning has remained broadly speculative and disengaged from applications. Logical formalisms have not been forthcoming that would be useful either in designing an agent that needs to act intelligently, or in helping an intelligent agent to evaluate its reasoning about action. (shrink)