An Informational Theory of Counterfactuals

Theoretical Linguistics, 2021

The analysis of counterfactuality needs a good shake-up. Wolfgang Klein's article does an excellent job in pointing out what is stale and unproductive in the literature, often inherited from philosophical discussions with limited linguistic relevance. And he posits a fresh alternative that is closer to the linguistic facts, especially as we know them from English and other Germanic languages. In this response we discuss three points that, we believe, are compatible with Klein's proposal but may bring it even closer to the linguistic facts, including for languages not discussed in Klein's paper. Apart from English, the data we use mainly come from our work on Australian languages (Verstraete 2005a, 2006, Luk in preparation), but also from a study of a broader cross-linguistic sample (Van linden & Verstraete 2008). 1. Polarity reversal rather than truth or falsity Much of the discussion of counterfactuality is framed in terms of truth or falsity (like the term itself, in fact), as inherited from work in logic and adjacent areas of philosophy. Klein's target article nicely points out that there are problems with this approach: neither counterfactual protases nor apodoses have to be 'contrary to the facts', as demonstrated by his examples (4) and (5). Instead, Klein proposes an analysis in terms of the relation between actual and nonactual worlds: a counterfactual protasis introduces a world that is not the actual one but otherwise warranted as the actual one. Under this analysis, the default interpretation of this type of protasis as 'contrary to the facts' comes from the fact that not talking about the actual world typically has a reason, the most obvious one being "that nothing can be said about the actual world" (p. 26). But this does not preclude that the situation in the protasis could also apply to the actual world, as in Klein's example (4). The last part of this argument is somewhat similar in spirit to Gricean approaches to counterfactuals (Ziegeler 2000, Verstraete 2005a, Van linden & Verstraete 2008), which state that in a 'knowable' domain like the past, using a modalized expression (e.g. X would have Yed) is less informative than using its bare counterpart (X Yed), and thus triggers the quantity-based implicature that 'X Yed' does not apply, i.e. 'X did not Y'. As an implicature, however, this can be cancelled and is thus not an inherent part of the semantics of counterfactuals, just as Klein shows for his (4).

docenti.lett.unisi.it

The first part of the paper summarizes Lewis' counterfactual theory of causation and emphasizes Lewis' refusal to require the temporal priority of causes. Lewis holds that in order to achieve a correct theory of causality it is enough to observe that backtracking counterfactuals are ordinarily false. Lewis argues that the well-known asymmetry between an open future and a closed past goes hand in hand with the asymmetry of counterfactual dependence, that in his view is justified by an adequate analysis of the similarity of worlds. Lewis holds that similarity should be intended as Overall Similarity, but with the proviso that "big" miracles create big dissimilarities while "little" miracles before the antecedent may be essential to grant high similarity. §4 examines some criticism of Lewis' conception of similarity and miracles. In §5 it is argued that Lewis' contention that backtracking counterfactuals are normally false is misplaced, since it may be shown that in a suitably rich logical language every factual true forward-looking conditional is equivalent to a true backtracking counterfactual.

Synthese 289(1), 29-57 (2012).

Counterfactuals are contrary to fact conditionals of the form, If A were the case then B would be the case. In this usage, A is usually false or untrue in the world so that A is contrary to fact or counterfactual. The semantics of counterfactuals is normally developed according to the principle of similarity, and the key point is to specify the notion of relative similarity. In this paper, we focus on a specific type of counterfactuals called causal counterfactuals and study in detail its applications to the philosophy of science. We consider Causal counterfactuals such as for e.g., 'if the ignition key had been turned then the car would have started' and causal conditionals e.g., 'if the ignition key was turned then the car started'. These counterfactuals hold because of the causal relationship between the antecedent and consequent. It is the connection between counterfactuals and causation that makes them relevant to social science research. Research on counterfactuals have attracted wide attention amongst philosophers and AI community. in the recent years, much work on counterfactuals in philosophy are focussed on criteria for judging the counterfactuals to be true. In this paper, we deal with the semantics of counterfactuals and address some of the challenges being addressed in the traditional and recent work on theories of counterfactuals. Counterfactuals finds utmost importance in analyzing laws, causality and explanation.

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.

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.)

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

Linguistics and Philosophy, 2018

Based on a crowdsourced truth value judgment experiment, we provide empirical evidence challenging two classical views in semantics, and we develop a novel account of counterfactuals that combines ideas from inquisitive semantics and causal reasoning. First, we show that two truth-conditionally equivalent clauses can make different semantic contributions when embedded in a counterfactual antecedent. Assuming compositionality, this means that the meaning of these clauses is not fully determined by their truth conditions. This finding has a clear explanation in inquisitive semantics: truth-conditionally equivalent clauses may be associated with diierent propositional alternatives, each of which counts as a separate counterfactual assumption. Second, we show that our results contradict the common idea that the interpretation of a counterfactual involves minimizing change with respect to the actual state of affairs. We propose to replace the idea of minimal change by a distinction between foreground and background for a given counterfactual assumption: the background is held fixed in the counterfactual situation, while the foreground can be varied without any minimality constraint.

Synthese, 2017

In this paper I present a limitation to what may be called strictly-interventionistic causal-model semantic theories for subjunctive conditionals. And I offer a line of response to Briggs' (Philos Stud 160:139–166, 2012) counterexample to Modus Ponens—given within a strictly-interventionistic framework—for the subjunctive conditional. The paper also contains some discussion of backtracking counterfactuals and backtracking interpretations. The limitation inherent to strict inter-ventionism is brought out via a class of counterexamples. A causal-model semantics is strictly interventionistic just in case the procedure it gives for evaluating a subjunctive conditional requires making the values of the variables implicated in the antecedent independent from the values of the parents of these antecedent variables. Most causal-model semantic theories that have gained attention are strictly interventionistic.

Siegal, Elitzur and Nora Boneh (eds.), Perspectives on Causation, Springer., 2020

Counterfactual conditionals are used extensively in causal reasoning. This observation has motivated a philosophical tradition that aims to provide a counterfactual analysis of causation. However, such analyses have come under pressure from a proliferation of counterexamples and from evidence that suggests that the truth-conditions of counterfactuals are themselves causal. I offer an alternative account of the role of counterfactuals in causal thought that is consistent with these data: counterfactuals are used in a common method of causal reasoning related to John Stuart Mill's method of difference. The method uses background beliefs about causal relationships, history, and the natural laws to establish a new causal claim. Counterfactuals serve as a convenient tool for stating certain intermediate conclusions in this reasoning procedure, and that is part of what makes counterfactuals useful. This account yields a functional explanation of why our language contains a construction with the truth-conditions of counterfactuals. 3 For an interesting alternative explanation of the connection between causation and counterfactuals, see Maudlin (2004). 4 I do not claim that that is the only function of counterfactual conditionals. They clearly also serve other purposes, e.g. in making practical decisions.