Research

This paper is concerned with disjunctions of conditionals, such as If Alice dances, Charlie will dance, or if Bob dances, Charlie will dance, and disjunctions of universal modals, such as You have to clean your room or you have to walk the dog. We aim to provide a uniform account of their surprising behaviour. Our proposal combines two independently-attested features of disjunction. Firstly, disjunction’s dynamic effect: the fact that the second disjunct of a disjunction is typically interpreted assuming the negation of (a subclause of) the first, and perhaps symmetrically, that the first is interpreted assuming (a subclause of) the second. Secondly, the fact that disjunctions often receive a conjunctive interpretation, familiar from free choice phenomena.

The similarity approach to conditionals (Stalnaker 1968; Lewis 1973) predicts Reciprocity to be valid: whenever A > B, B > A and A > C are true, B > C is true too (where A > B denotes if A would B). We ran an experiment to test the validity of this rule. Strikingly, half of our participants judged the rule invalid, i.e. judged in at least one scenario that it does not preserve truth. Our data also challenge Kratzer’s (2012) and Fine’s (2012) semantics of conditionals, but we show that McHugh’s (2022; 2023) aboutness approach can account for our data.

We show that a single operation can account for three seemingly distinct properties of the semantics of cause and because. The properties are, firstly, their comparative nature: interpreting cause and because involves comparing what would happen in the presence of the cause (a positive condition) with what would happen in the absence of the cause (a negative condition). Secondly, there is an asymmetry in logical strength between the two conditions: the positive condition involves a universal modal while the negative condition involves an existential modal. Thirdly, the positive and negative conditions have the same modal base, i.e. are interpreted while assuming the same set of background facts. Despite their apparent dissimilarity, we show that these three properties are predicted by a single operation: exhaustification. The comparative nature of cause and because follows from the comparative nature of exhaustification, which compares a sentence with its alternatives. The asymmetry in strength arises because exhaustification negates alternatives: given the duality between universal and existential quantification, negation flips a necessity modal into a possibility modal, producing the observed strength asymmetry. Finally, the positive and negative condition have the same modal base since, rather cause and because having two modals in their semantics—one for the positive condition and one for the negative condition—their semantics contains a single modal which is copied by exhaustification. We conclude by showing that this exhaustification operator violates Economy constraints, suggesting that it is not subject to licensing conditions but part of lexical semantics of cause and because.

In this paper I would like to offer a new framework for hypothetical reasoning, with the goal of predicting what scenarios we consider when we interpret a conditional or causal claim (such as a sentence containing the word because). The idea is that when we interpret a conditional or causal claim, we identify a part of the world to change and imagine changing that. Sentences are about parts of the world: when we interpret a conditional antecedent or because clause, we allow the part of the world it is about to vary. This expands our modal horizons, which we restrict to those scenarios where the sentence we are asked to imagine true is indeed true. To evaluate a whole conditional or causal claim we look to the possible futures after this change.

My main evidence for this approach is that it gives just the right range of hypothetical scenarios to account for how we interpret both conditionals and causal claims. Some approaches (such as Stalnaker and Lewis’s semantics of conditionals based on similarity, and Kratzer’s premise semantics) consider too few scenarios, while others (such as Fine’s 2012 truthmaker semantics of conditionals) consider too many. The present approach inhabits a Goldilock's zone between these extremes: not too restrictive, not too permissive, but just right.

Is the truth of a causal claim always preserved by strengthening the cause? For instance, does “Alice flicking the switch caused the light to turn on” entail “Alice flicking the switch and it raining in New Zealand caused the light to turn on”? We argue for this entailment, proposing that causal claims are downward monotone in their cause: if  entails C then (C caused E) entails  caused E). In other words, causes are never too strong. We argue for this by presenting examples of causal claims that are assertable even though the cause is stronger than required for the claim to be true. These data challenge accounts (the most prominent of which is Halpern, Actual Causality 2016) that predict such sentences to be false. Instead, we trace differences in their acceptability to their scalar implicatures. Finally, we show that Halpern’s semantics of causal claims can be easily adapted to account for the data we consider; namely, by dropping his ‘minimality’ condition.

A number of authors, beginning with Alonso-Ovalle (2006), have used conditional antecedents to argue for the presence of alternatives in semantics. In this tradition, recent experimental work from Ciardelli et al. (2018b) and Schulz (2018) uses data from conditional antecedents to investigate the interaction between negation and alternatives. We contribute to this line of inquiry with an experiment to test a number of semantics of conditionals through their predictions on the relationship between alternatives and negation (namely, Fine 2012, Alonso-Ovalle 2006, Ciardelli et al. 2018b, Willer 2018, Schulz 2018). We find experimental support for a variant of Schulz’s theory and against all other accounts we consider.

Ciardelli et al. (2018b) adopt the framework of inquisitive semantics to provide a novel semantics for counterfactuals. They argue in favour of adopting inquisitive semantics based on experimental evidence that De Morgan’s law, which fails in inquisitive semantics, is invalid in counterfactual antecedents. We show that a unique feature of inquisitive semantics—the fact that its meanings are downward closed—leads to difficulties for Ciardelli et al.’s semantic account of their data. The scenarios we consider suggest either adopting a semantic framework other than inquisitive semantics, or developing a non-semantic explanation of the phenomena Ciardelli et al. (2018b) seek to explain.

We present a class of diagrams in which to reason about causation. These diagrams are based on a formal semantics called ‘system semantics’, in which states of systems are related according to temporal succession. Arguing from straightforward examples, we provide the truth conditions for causal claims that one may make about these diagrams.

This thesis aims to answer two questions about causal claims (such as sentences containing cause or because). Firstly, the modelling question: what kind of information do we use when we judge that a causal claim holds? Secondly, the meaning question: under what conditions do we judge that a causal claim is true?

Our answer to the modelling question is that a causal model must contain time, part–whole structure, and nomic possibility. The model represents scenarios as extended in time, with each moment in time having a mereological structure (the mereological structure tell us, for example, that the state of Amsterdam is part the state of the Netherlands). The notion of nomic possibility specifies which worlds are nomically possible and which worlds are nomically impossible; in other words, which worlds satisfy the laws and which do not. In addition, the model must also contain two language-related components. For each sentence, the model must tell us what parts of the world it is about, and in which worlds the sentence is true.

We show that this modelling framework is strictly more general than a popular alternative, that of structural causal models. Every structural causal model can be represented into our framework, and therefore every scenario that structural causal models can represent our framework can represent too. However, the converse does not hold. There are some scenarios that our proposed model can represent which structural causal models cannot.

We use these components to analyse how people construct hypothetical alternatives to reality. For it is commonly thought that the truth of a causal claim depends not only on what goes on in the actual world, but on what happens in some hypothetical scenarios as well. For example, when we evaluate Alice missed her flight because she got stuck in traffic we imagine scenarios where she is stuck in traffic and scenarios where she is not, and compare what happens in each.

We then analyse the semantics of cause and because in terms of two relations: sufficiency and production. The meaning of cause and because is a blend of these relations: C cause E and E because C are true just in case C is true, and C is sufficient to produce E but C's negation is not.

If Socrates resembled Adonis, they would both be handsome. If Adonis resembled Socrates, neither would be handsome. And if Adonis and Socrates resembled each other, they might both be handsome and they might not. This is a puzzle for theories of conditionals that predict ‘if A, would C’ and ‘if B, would C’ to be equivalent whenever A and B have the same truth conditions. For Socrates resembles Adonis just in case Adonis resembles Socrates, which holds just in case they resemble each other. Moreover, their corresponding facts, or truthmakers, are plausibly taken to be the same: the state of Socrates resembling Adonis is identical to the state of Adonis resembling Socrates, which is identical to the state of them resembling each other. I show that this puzzle cannot be solved by appealing to de re readings of the comparator, and offer a solution by developing a semantics of conditionals that is sensitive to what conditional antecedents are about.

It is said that causes make a difference to their effects, and that for a belief to count as knowledge, the state of the world must make a difference to the belief. But what does it mean to make a difference? We propose a simple, literal analysis. Something makes a difference if and only if, when we compare its presence with its absence, there is a difference; there is something that holds if the difference-maker is present but not if it is absent. We use this to define the notion of a difference-making relation. A wide variety of relations turn out to be difference-making relations in our sense, such as probability raising, casual dependence, and causation (according to numerous analyses of causation). We show that the notion of difference-making is independent of the semantics of conditionals, in the sense that under minimal assumptions all theories of conditionals agree on which relations count as difference-making relations. It also does not matter whether we require the difference D to not hold if the difference-maker A is absent (i.e. require if ¬A, ¬D), or instead that it is false that the difference holds if the difference-maker is absent (i.e. require ¬(if ¬A, D)). The two resulting notions of difference-making turn out to be equivalent. Finally, we compare our analysis of difference-making with a previous analysis by Carolina Sartorio (2005 ‘Causes as Difference Makers’, Philosophical Studies), one that at first glance seems quite different, but is surprisingly equivalent to our own.

In this essay we analyse reasons why, as they appear, for example, in claims such as The reason why the chicken crossed the road was to get to the other side and The government deregulating banks is a reason why the 2008 financial crash happened. We propose that R is a reason why P just in case P because R is true, and optionally, the relevant agent believes that P because R is true. In other words, reason statements are equivalent to because statements with an optional subjective component.

According to a long tradition, causes necessitate their effects. The occurrence of a cause guarantees the occurrence of its effects, relative to a set of background conditions. Recent analyses of causation, however, omit this sufficiency requirement altogether, requiring that the cause and effect occur, but beyond that considering only what would happen were the cause absent. The article presents a new argument for the sufficiency requirement. To illustrate, suppose Ali was born in Ireland and received an Irish passport. “Being born in Europe caused Ali to receive an Irish passport” is intuitively unacceptable, even though if Ali hadn't been born in Europe, he likely wouldn't have received an Irish passport, and even though  in the closest world where Alice is born in Europe (namely, the actual one), he does. However, being born in Europe is not sufficient to receive an Irish passport. Incoroporating sufficiency inot the meaning of cause allows us to explain why the above sentence is false.