As literary realism shed earlier providential paradigms, William Thackeray inaugurated a startling interest in alternatives to reality as essential for novels that would be true to life. These “queer speculations” saturate his writing: a child who might have lived, an accident that could have been avoided, a war that would have ended otherwise if only …. Thackeray’s counterfactual imagination matures from occasional stories of the 1840s, through Vanity Fair (1847–48), the Roundabout Papers (1860–63), and Lovel the Widower (1860). His conditionals range from frenzied anticipation to paralyzing regret, developing from wild wagers and total reversals of fortune in the early sketches to a late style where memory, narrative, and writing itself are marked by virtuality. This chapter examines uncertain experience in Thackeray’s oeuvre in relation to historical writing of the eighteenth and nineteenth centuries and accounts of counterfactual reasoning in psychology and narrative theory. Probing uncertainty’s emotional and tonal modulations, Thackeray’s writing widens the space of novelistic realism to include the nonmimetic, hypothetical, improbable, and open-ended – or what he terms the “might-have-beens.”

We provide a lay-language primer on the counterfactual model of causal inference and the logic of causal models. Topics include the representation of causal models with causal graphs and using causal graphs to read off relations of conditional independence among variables in a causal domain.

Chapter 3 considers the underlying narrative structures of Corippus’ epic and how the poet positions the campaigns of John Troglita in their wider context. The Iohannis surveys the events of circa 530–46 in a series of analeptic ‘flashbacks’. As a succinct verse history of North Africa between the late 520s and 546, these surveys differ wildly from contemporary imperial propaganda. This chapter argues that these accounts must be considered as meaningful responses to the recent past within Byzantine Africa and as functional parts of the Iohannis. It is argued that Corippus’ presentation of these counter-narratives created a space for the interrogation of a complex past which would otherwise have been unavailable to him.

The second part of the chapter looks at the prolepses in the Iohannis, where Corippus’ narrative moves from the narrated time of John’s campaigns to their anticipated resolution and the composition of the epic itself. This teleology is not only explored through many direct references to the coming Roman triumph, but also to the counterfactual ‘futures’ anticipated by the Moors. Corippus’ resolution of these accounts through authorial interjections help to underscore the inevitability of imperial victory while emphasizing the sense of crisis within the historical narrative.

This chapter looks at the tools and procedures that programmes use to assess claims. Assessing a redress claim involves deciding which injuries to redress and how much money to pay. Those judgements are difficult. Since people will reasonably disagree, good procedure is essential. Enabling survivors to choose how the programme will assess their claims can help protect survivors’ privacy and well-being and make programmes more effective and efficient.

A counterfactual of what might have happened if Churchill rather than Chamberlain had become chancellor and then prime minister is used to compare the two men. The evidence suggests foreign policy would have differed little before 1938. Like Chamberlain, Churchill would have prioritised the German threat over the Japanese, and would have tried to gain Italian support. Nor would he have used force to reverse Hitler’s occupation of the Rhineland or the Anschluss. On the other hand, Churchill’s approach to Czechoslovakia was fundamentally different from Chamberlain’s, being based on collective security rather than bilateral negotiations with Hitler. It is uncertain, however, whether an effective alliance could have been constructed to deter Germany. Churchill would have rearmed more rapidly than Chamberlain, being more willing to take risks with the economy, but both men prioritised the air force over the army, and for technical reasons British air power was not formidable in 1938. The question of whether it would have been better nevertheless to fight in 1938 rather than 1939 cannot be answered with certainty. Chamberlain’s personal diplomacy undoubtedly had serious shortcomings, but there is room for disagreement on moral issues associated with the Churchillian alternative, including the sacrifice of Ethiopia; the use of war as an instrument of foreign policy, particularly when public opinion was not united; and the risk of allowing Stalin to decide whether there should be peace or war.

Issues of measuring policy impacts from observed data are discussed. Popular methods for controlling the bias induced by nonrandom samples and panel parametric, semi-parametric, and nonparametric methods are introduced. Conditions for simulating program impacts are discussed and examples are given.

In Chapter 6, we defend the difference-making thesis of Causal Mechanism, that is, the view that mechanisms are underpinned by networks of difference-making relations, by showing that difference-making is more fundamental than production in understanding mechanistic causation. Our argument is two-fold. First, we criticise Stuart Glennan’s claim that mechanisms can be viewed as the truth-makers of counterfactuals and argue that counterfactuals should be viewed as metaphysically more fundamental. Second, we argue against the view that the productivity of mechanisms requires thinking of them as involving activities, qua a different ontic category. We criticise two different routes to activities: Glennan’s top-down approach and Phyllis Illari and Jon Williamson’s bottom-up approach. Given these difficulties with activities and mechanistic production, it seems more promising to start with difference-making and give an account of mechanisms in terms of it.

In Chapter 5, we examine the relation between mechanisms and laws/counterfactuals by revisiting the main notions of mechanism found in the literature. We distinguish between two different conceptions of ‘mechanism’: mechanisms-of and mechanisms-for. We argue that for both mechanisms-of and mechanisms-for, counterfactuals and laws are central for understanding within-mechanism interactions. Concerning mechanisms-for, we claim that the existence of irregular mechanisms is compatible with the view that mechanisms operate according to laws. The discussion in this chapter, then, points to an asymmetrical dependence between mechanisms and laws/counterfactuals: while some laws and counterfactuals must be taken as primitive (non-mechanistic) facts of the world, all mechanisms depend on laws/counterfactuals.

Given the centrality of counterfactual difference-making relations to the argument of the book, in Chapter 7 we say a few more things about contrary-to-fact conditionals. We offer a primer on the logic and the semantics of counterfactuals, focusing on the two main schools of thought: the metalinguistic and the possible-worlds approach. We also present and examine James Woodward’s interventionist counterfactuals and the Rubin-Holland model. We argue that the counterfactual approach is more basic than the mechanistic, but information about mechanisms can help sort out some of the methodological problems faced by the counterfactual account.

Chapter 2 starts by placing experiments in the scientific process – experiments are only useful in the context of well-motivated questions, thoughtful theories, and falsifiable hypotheses. The author then turns to sampling and measurement since careful attention to these topics, despite being often neglected by experimentalists, are imperative. The remainder of Chapter 2 offers a detailed discussion of causal inference that is used to motivate an inclusive definition of “experiments.” The author views this as more than a pedantic exercise, as careful consideration of approaches to causal inference reveals the often implicit assumptions that underlie all experiments. The chapter concludes by touching on the different goals experiments may have and the basics of analysis. The chapter serves as a reminder of the underlying logic of experimentation and the type of mindset one should have when designing experiments. A central point concerns the importance of counterfactual thinking, which pushes experimentalists to think carefully about the precise comparisons needed to test a causal claim.

Counterfactuals are central to positivist and interpretivist claims to knowledge. They are used to evaluate propositions, theories, and causal narratives and also to imagine them. In different ways, the failure to consider counterfactual claims or deploy counterfactual arguments weakens claims to knowledge in both research traditions.