Marks and Probabilities: Two Ways to Find Causal Structure

1. What is commonly called Reichenbach’s “Principle of the Common Cause” is not a general criterion for a common cause, as many philosophers nowadays suppose. Examples include W. Salmon in his accounts of causal processes and Bas van Fraassen in his new book on quantum mechanics, in which he argues that the quantum world has no causal structure. 2. This does not matter for Reichenbach’s purposes. Indeed it should not be surprising from his point of view that in different situations we need different criteria or different methods for testing for the same phenomenon. 3. The third thesis begins from a question: Where do probabilistic criteria for causality come from?