A critique of Suppes' theory of probabilistic causality

An analysis of causality has been particularly troublesome, and thus mostly ignored, by those who believe the world is indeterministic. Patrick Suppes has attempted to give an account of causality that would hold in both deterministic and indeterministic worlds. To do this, Suppes uses probability relations to define causal relations. The main problems facing a probabilistic theory of causality are those of distinguishing between genuine and spurious causes as well as direct and indirect causes. Suppes presents several definitions of different types of causes in an attempt to capture the distinction between genuine and spurious causes and direct and indirect causes. It is my claim that Suppes' definitions fail to distinguish among genuine and spurious causes and direct and indirect causes. To support this claim I will give some counterexamples to Suppes' theory. I will then modify some of Suppes' definitions in a natural manner, and show that even with modification they are still prone to counterexamptes. The main thrust here is that Suppes' account of causation is intrinsically defective. I believe that there is no way to differentiate genuine from spurious causes or direct from indirect causes using only probability relations; thus no minor modifications of Suppes' definitions will be sufficient to resolve these difficulties. While presenting counterexamples to Suppes' definitions, I will also try to explain in principle why each particular example is a counterexample to Suppes' theory. After presenting these counterexamples, I will introduce the idea of an interactive fork and use it to argue that the basic intuition around which Suppes built his theory is faulty. In the last section of the paper I will discuss the more fundamental issue of whether all positive causes must raise the probabilities of their effects. Although this issue lies at the heart of most probabilistic accounts of causality, it has largely been ignored in the literature. I hope to show that we are not justified in believing that positive causes always raise the probability of their effects and that more discussion is needed on this important subject.