Abstract

In this paper, I investigate the study of causal mechanisms in the social sciences. I argue that unless one adopts a clear notion of causation, such as Woodward's manipulability theory of causation, one does not find evidence for causal claims. I show that adopting Woodward’s theory entails that a researcher must take into account both the observable implications of the mechanisms, and possible interventions on those mechanisms. In a backlash against the pervasiveness of statistical methods, in the last decade or so social scientists have become more focused on finding the causal mechanisms behind observed correlations. To provide evidence for such causal claims, researchers often rely on process-tracing, a method which involves contrasting the observable implications of several alternative mechanisms. Although process-tracing has gained prominence as a technique, researchers do not share a fundamental framework of what causation is. I will show what process-tracers’ reasoning would look like if they were to commit to Woodward’s manipulability theory. This theory tells us that any successful explanation of an effect must refer to causal factors that could be manipulated to change the phenomenon under study. Specifically, a variable X is a cause of another variable Y if there exists some ‘intervention variable’ I. I is an intervention variable if we can use I to change X, which will then in turn change Y without any interference of other variables linked to Y. In other words, using I we will be able to ascertain that it was X that made the change in Y happen. I will argue that if a process-tracing researcher were to adopt the manipulability notion of causation, she would not only have to find observable implications of the alternative mechanisms under study, but also information regarding an intervention variable for each link of the causal chain.