A textbook on modal logic, intended for readers already acquainted with the elements of formal logic, containing nearly 500 exercises. Brian F. Chellas provides a systematic introduction to the principal ideas and results in contemporary treatments of modality, including theorems on completeness and decidability. Illustrative chapters focus on deontic logic and conditionality. Modality is a rapidly expanding branch of logic, and familiarity with the subject is now regarded as a necessary part of every philosopher's technical equipment. Chellas here offers an (...) up-to-date and reliable guide essential for the student. (shrink)

Counterfactuals is David Lewis' forceful presentation of and sustained argument for a particular view about propositions which express contrary to fact conditionals, including his famous defense of realism about possible worlds and his theory of laws of nature.

This paper presents a nonmonotonic deontic logic based on commonsense entailment. It establishes criteria a successful account of obligation should satisfy, and develops a theory that satisfies them. The theory includes two conditional notions of prima facie obligation. One is constitutive; the other is epistemic, and follows nonmonotonically from the constitutive notion. The paper defines unconditional notions of prima facie obligation in terms of the conditional notions.

Hans Kamp; IV*—Free Choice Permission, Proceedings of the Aristotelian Society, Volume 74, Issue 1, 1 June 1974, Pages 57–74, https://doi.org/10.1093/aristoteli.

In this paper, I discuss the distribution and interpretation of free choice items (FCIs) in Greek, a language exhibiting a lexical paradigm of such items distinct from that of negative polarity items. Greek differs in this respect from English, which uniformly employs any. FCIs are grammatical only in certain contexts that can be characterized as nonveridical (Giannakidou 1998, 1999), and although they yield universal-like interpretations in certain structures, they are not, I argue, universal quantifiers. Evidence will be provided that FCIsare (...) indefinites; the quasi-universal effect is shown to be the result of binding by an operator with universal force. Additionally, the limited distribution of FCIs in non veridical contexts can be accounted for by analyzing them as indefinites which must always be interpreted in an intensional type. The difference between ``regular'' indefinites and FCIs, therefore, is reduced to a type difference which captures the fact that only the latter exhibit limited distribution: because of their intensional type, FCIs will be grammatical only in contexts providing alternatives (worlds or situations), and nonveridical contexts do exactly this. By contrast, FCIs are excluded from veridical and episodic contexts because these provide no alternatives and hence do not satisfy the lexical semantic requirement ofFCIs. The proposed analysis is supported by data from other languages as well (Spanish, Catalan,French) and has important consequences regarding the analysis of English any. If FCIs are not universal quantifiers but indefinites, then the usual ambiguity thesis (free choice any being universal, negative polarity any an existential) can no longer be maintained, at least not as one in terms of quantificational force. (shrink)

This paper offers an explanation of the fact that sentences of the form (1) ‘X may A or B’ may be construed as implying (2) ‘X may A and X may B’, especially if they are used to grant permission. It is suggested that the effect arises because disjunctions are conjunctive lists of epistemic possibilities. Consequently, if the modal may is itself epistemic, (1) comes out as equivalent to (2), due to general laws of epistemic logic. On the other hand, (...) on a deontic reading of may, (2) is only implied under exceptional circumstances – which usually obtain when (1) is used performatively. (shrink)

In this paper, the meanings of sentences containing the word or and a modal verb are used to arrive at a novel account of the meaning of or coordinations. It is proposed that or coordinations denote sets whose members are the denotations of the disjuncts; and that the truth conditions of sentences containing or coordinations require the existence of some set made available by the semantic environment which can be ‘divided up’ in accordance with the disjuncts. The relevant notion of (...) ‘dividing things up’ is made explicit in the paper. Detailed attention is given to the question of how the proposed truth conditions are derived from the syntactic input. The account offered allows for the derivation of both the disjunctive and the nondisjunctive readings of modal/or sentences, including the much-discussed free choice readings of may/or sentences. (shrink)

I present an analysis of Free Choice Items (FCIs), based on Scandinavian, where FCIs are complex and distinct from polarity sensitive items. Scandinavian FCIs are argued to have two components. One is a universal quantifying into modal contexts. The other is an operator mapping a type (s,t) expression onto itself, adjoining to the closest type t or (s,t) expression. Thus invoking Intensional Functional Application, this operator requires the presence of a modal in the scope of the universal quantifier. Facts concerning (...) ‘essential connections’ and ‘existential import’ are accounted for by assuming that the FC determiner has the option of acting like a quantifier. (shrink)

The four main essays in this volume investigate new sectors of the theory of decision, preference, act-characteristics, and action analysis. Herbert A. Simon applies tools developed in the theory of decision-making to the logic of action, and thereby develops a novel concept of heuristic power. Adapting ideas from utility and decision theory, Nicholas Rescher proposes a logic of preference by which conflicting theories proposed by G. H. von Wright, R. M. Chisholm, and others can be systematized. Donald Davidson discusses difficulties (...) in specifying the structure of action sentences to elucidate how their meaning depends on that structure. G. H. von Wright devises a method for describing each “state of the world” that results from an action, in a revision of his own earlier work. Additionally, a study of the logic of norms by Alan Ross Anderson is presented as an appendix, along with an appendix by Rescher outlining the aspects of action. (shrink)