Singular Causation

1. Singular vs. general causation In many people, caffeine causes slight muscle tremors, particularly in their hands. In general, the Caffeine → Muscle Tremors causal connection is a noisy one: someone can drink coffee and experience no hand shaking, and there are many other factors that can lead to muscle tremors. Now suppose that Jane drinks several cups of coffee and then notices that her hands are trembling; an obvious question is: did this instance of coffee drinking cause this instance of hand-trembling? Structurally similar questions arise throughout everyday life: Did this pressing of the 'k' key cause this change in the pixels on the computer monitor? Did these episodes of smoking cause this lung cancer? Did this studying cause this test score? And so on. These questions all ask about singular causation in a particular situation, in contrast with general causation across multiple cases. They are thus particularly salient in situations in which we care about that specific case, as in many legal contexts, social interactions, physical explanations of anomalous events, and more. Singular causation is cognitively challenging, as it is quite unclear how we could come to know that, say, this coffee drinking caused these muscle tremors. On the one hand, we cannot directly observe singular causation, as famously noted by David Hume (1748), but instead observe only sequences of events. One might hope that so-called causal perception (see also White, this volume) could provide a way to directly observe singular causation, but there are reasons to suspect that causal perception is not just the straightforward observation of singular causation. The particular events must instead be understood or interpreted in light of background causal knowledge. On the other hand, we cannot use statistical or other inductive inference methods to learn directly about which singular causation relations obtain because we have (by definition) only a single case. There are many different methods for inferring causal structure from observations, but those all require multiple cases, so are not directly applicable for singular causation. Moreover, even if they were usable, the causal relations across multiple situations need not perfectly track the causal relations in any particular case. For example, it is perfectly consistent for caffeine to cause shaky hands, but for these particular muscle tremors to be caused by this dose of medication, rather than the coffee that one just consumed. Judgments about singular causation require more than just knowledge of …