A Difficulty for the Possible Worlds Analysis of Counterfactuals

Journal of Philosophy, 109(3), pp. 221-46 (2012)

Mind, 2006

On the received view, counterfactuals are analyzed using the concept of closeness between possible worlds: ‘if it had been that p, then it would have been the case that q’ is true at world w just in case q is true at all the possible p-worlds closest to w. The degree of closeness between two worlds is usually thought to be determined by weighting different respects of similarity between them. The question I consider in the paper is which weights attach to different respects of similarity. I start by considering Lewis’s answer to the question and argue against it by presenting several counterexamples. I use the same examples to motivate a general principle about closeness: If a fact obtains in both of two worlds, then this similarity is relevant to the closeness between them if and only if the fact has the same explanation in the two worlds. I use this principle and some ideas of Lewis’s to formulate a general account of counterfactuals, and I argue that this account can explain the asymmetry of counterfactual dependence. The paper concludes with a discussion of some examples that cannot be accommodated by the present version of the account and therefore necessitate further work on the details.

Synthese, 1994

In this paper I explore the ambiguity that arises between two readings of the counterfactual construction, the n-d and the l-p, analyzed in my book A Theory of Counterfactuals. I then extend the analysis I offered there to counterfactuals with true antecedents, and offer a more precise formulation of the conception of temporal divergence points used in the 1-p interpretation. Finally, i discuss some ramifications of these issues for counterfactual analyses of knowledge. t. B A C K G R O U N D In A Theory of Counterfactuals 1 (henceforth: A TC) I discussed the two major counterfactual interpretations, the n-d and the l-p. The first applies to counterfactuals, the antecedents of which are compatible with their prior histories; the second to counterfactuals whose antecedents are incompatible with their prior histories. Together they cover counterfactuals, with premises that are factual (non-nomic), false, and logically, n , m , logically, and metaphysically possible. 2 These two are by far the most prevalent kinds of counterfactual interpretations: all counterfactuals which are not covered by these two are either esoteric or parasitic on counterfactuals which are covered by these two. (Some types of such esoteric or parasitic counterfactuals are also discussed in A TC3). After a brief survey of the n-d and t-p interpretations, I will elaborate further on the l-p interpretation and then pursue the ambiguity the two interpretations generate.

Acta Analytica, 2018

Backtracking counterfactuals are problem cases for similarity based theories of coun-terfactuals (e.g. Lewis, 1979). Hiddleston (2005) proposes a causal theory of counterfactuals, which deals well with backtracking. In addition, the causal theory provides an unified account for non-backtracking and backtracking counterfactuals. In this paper, I present a backtracking counterfactual that is a problem case for Hiddleston's account. Then I propose an informational theory of counterfactuals, which deals well with this problem case maintaining the good features of the causal theory. In addition, the informational theory provides clues for the semantics and the epistemology of counterfactuals. The idea is that backtracking is adequate when the (possibly non-actual) state of affairs expressed in the antecedent of a counterfactual transmits less information about an event in the past than the actual state of affairs.

Analysis, 2008

Philosophical Perspectives 20, pp. 237-302, 2006

The goal of this paper is to give an account of what it is for a proposition to be metaphysically necessary, and an explanation of the raison d'être of modal concepts. Both projects have their starting point in the idea that modal notions originate in our cognitive practice of counterfactual reasoning, i.e. of answering questions of the form ‘how would things be different if such-and-such were the case?’.

Mind 2014, Vol. 123: 1021-55.

The pattern of credences we are inclined to assign to counterfactuals challenges standard accounts of counterfactuals. In response to this prob- lem, the paper develops a semantics of counterfactuals in terms of the epsilon-operator. The proposed semantics stays close to the standard ac- count: the epsilon-operator substitutes the universal quantifier present in standard semantics by arbitrarily binding the open world-variable. Various applications of the suggested semantics are explored including, in particu- lar, an explanation of how the puzzling credences in counterfactuals come about.

The uploaded document contains my PhD dissertation. The abstract is given below. ABSTRACT The two main features of this thesis are (i) an account of contextualized (context indexed) counterfactuals, and (ii) a non-vacuist account of counterpossibles. Experience tells us that the truth of the counterfactual is contingent on what is meant by the antecedent, which in turn rests on what context is assumed to underlie its reading (intended meaning). On most conditional analyses, only the world of evaluation and the antecedent determine which worlds are relevant to determining the truth of a conditional, and consequently what its truth value is. But that results in the underlying context being fixed, when evaluating distinct counterfactuals with the same antecedent on any single occasion, even when the context underlying the evaluation of each counterfactual may vary. Alternative approaches go some of the way toward resolving this inadequacy by appealing to a difference in the consequents associated with counterfactuals with the same antecedent. That is, in addition to the world of evaluation and the antecedent, the consequent contributes to the counterfactual’s evaluation. But these alternative approaches nevertheless give a single, determinate truth value to any single conditional (same antecedent and consequent), despite the possibility that this value may vary with context. My reply to these shortcomings (chapter 4) takes the form of an analysis of a language that makes appropriate explicit access to the intended context available. That is, I give an account of a contextualized counterfactual of the form ‘In context C: If it were the case that … , then it would be the case that …’. Although my proposal is largely based on Lewis’ (1973, 1981) analyses of counterfactuals (the logic VW and its ordering semantics), it does not require that any particular logic of counterfactuals should serve as its basis – rather, it is a general prescription for contextualizing a conditional language. The advantage of working with ordering semantics stems from existing results (which I apply and develop) concerning the properties of ordering frames that facilitate fashioning and implementing a notion of contextual information preservation. Analyses of counterfactuals, such as Lewis’ (1973), that cash out the truth of counterfactuals in terms of the corresponding material conditional’s truth at possible worlds result in all counterpossibles being evaluated as vacuously true. This is because antecedents of counterpossibles are not true at any possible world, by definition. Such vacuist analyses have already been identified and challenged by a number of authors. I join this critical front, and drawing on existing proposals, I develop an impossible world semantics for a non-vacuist account of counterpossibles (chapter 5), by modifying the same system and semantics that serve the basis of the contextualized account offered in chapter 4, i.e. Lewis’ (1986) ordering semantics for the logic VW. I critically evaluate the advantages and disadvantages of key conditions on the ordering of worlds on the extended domain and show that there is a sense in which all of Lewis’ analysis of mere counterfactuals can be preserved, whilst offering an analysis of counterpossibles that meets our intuitions. The first part of chapter 1 consists of an outline of the usefulness of impossible worlds across philosophical analyses and logic. That outline in conjunction with a critical evaluation of Lewis’ logical arguments in favour of vacuism in chapter 2, and his marvellous mountain argument against impossible worlds in chapter 3, serves to motivate and justify the impossible world semantics for counterpossibles proposed in chapter 5. The second part of chapter 1 discusses the limitations that various conditional logics face when tasked to give an adequate treatment of the influence of context. That introductory discussion in conjunction with an overview of conditional logics and their various semantics in chapter 2 – which includes an in-depth exposition of Stalnaker-Lewis similarity semantics for counterfactuals – serves as the motivation and conceptual basis for the contextualized account of counterfactuals proposed in chapter 4. - - - - - - - - - - - - - - - - (Perhaps it is worth emphasizing that the most original work is contained in chapter 4, where I give an account of a contextualized (context relativized) counterfactual of the form ‘In context C: If it were the case that … , then it would be the case that …’, based on Lewis’ (1974, 1981) analysis of the counterfactual. Drawing on earlier work by Lewis (1973, 1981) I first give an ordering semantics for counterfactuals, based on the idea of comparative similarity, interpreted as ‘similarity in relevant respects’ or as ‘relevant similarity’, and modelled by total preorderings of possible worlds. Subsequently, building on that analysis I develop model-theoretic methods for a semantic consequence relation of contextualized counterfactuals (contextualized validity), which is given as the culminating item of the chapter.)

I offer a novel solution to the problem of counterfactual skepticism: the worry that all contingent counterfactuals without explicit probabilities in the consequent are false. I argue that a specific kind of contextualist semantics and pragmatics for would-and might-counterfactuals can block both central routes to counterfactual skepticism. One, it can explain the clash between would-and might-counterfactuals as in: (1) If you had dropped that vase, it would have broken. and (2) If you had dropped that vase, it might have safely quantum tunneled to China. Two, it can explain why counterfactuals like (1) can be true despite the fact that quantum tunneling worlds are among the most similar worlds. I further argue that this brand of contextualism accounts for the data better than other existing solutions to the problem.