We turn finally to the role of time in the theory of proper tylevel probabilistic causation. This will be dealt with in Sections 5.1 and 5.2, and this will complete the theory of property level probabilistic causation offered in this book. Section 5.3 offers some comparisons and contrasts between this theory and several others.

First, recall the problem that, at the beginning of Chapter 2, I called “the problem of temporal priority of the cause to the effect.” This problem arises from the fact that probabilistic correlation is symmetric. Leaving aside qualifications having to do with causal background contexts, if a factor X is a genuine probabilistic cause of a factor Y in a population, then X raises the probability of Y in that population. This implies that Y raises the probability of X in the same population. But we cannot infer that Y is a cause of X in the population, for while correlation is symmetric, causation is not.

Second, if we agree that property-level probabilistic causation is asymmetric, then we may want to capture this by saying that one factor can only be a cause of “later” factors, and that it can only be caused by “earlier” factors. But what is it for one factor itself–that is, one event type or one property – to be earlier or later than another? How can we make sense of the idea that such abstract things as factors (or types, or properties) enter into temporal relations among themselves?