Monday, August 29, 2005
Hume and Causal Perception
Chris points to this very cool discussion (PDF) of the development of causal perception in infants. My one quibble is that direct launching isn't so obviously prototypical; the tendency to think it so developed only in the past three hundred years. Prior to that, the prototypical case of physical causation was the steady (constant) push. That's why almost all serious discussions of causation prior to the 18th century assume that the primary form of causation is simultaneous causation (i.e., cause causing and effect happening are simultaneous -- indeed, are the same thing considered under different aspects). The tendency to assume that the primary form of causation is successive (i.e., cause causes then the effect happens) is something newer. Its origin is tricky to pin down, but might be roughly summarized as mechanism, occasionalism, and Hume, or even put into an even rougher and more summarized form as the billiard ball universe; this swept over the scene of thought, and attempts to restore some form of the simultaneous-dominant view (e.g., Lady Mary Shepherd's) were simply ignored. (As Shepherd argues at length, there are, in fact, good philosophical reasons for having a simultaneous-dominant rather than a successive-dominant view; for one thing, it more easily avoids skeptical paradoxes.) In fairness, the authors at a later point trace the sort of causation they are discussing to Hume. As I said, this is something of a quibble; direct launching, I suspect, is a much more fruitful field for experiment on causal perception than steady pushing is. As a sidenote, Hume's billiard ball example, which is mentioned in the chapter, actually comes from Malebranche. They both agree that the example shows that we have no objectively-grounded idea of causation between the two balls. Malebranche concludes that there must be some other cause at work; Hume concludes that our idea of causation must be subjectively-grounded (namely, in the irresistibility of inference created in us by constant conjunction). The entire section of Enquiry Section VII, in fact, is an interaction with Malebranche: Hume lifts several arguments without significant change from Malebranche's attack on scholastic theories of causation (he adds several of his own, however).