Abstract

The Common Cause Principle was introduced by HansReichenbach, in The Direction of Time, which was publishedposthumously in 1956. Suppose that two events A and Bare positively correlated: p(A∩B)>p(A)p(B)p(A∩B)>p(A)p(B)p(A\textbackslashcap B)>p(A)p(B). Suppose,moreover, that neither event is a cause of the other. Then,Reichenbach’s Common Cause Principle (RCCP) states that Aand B will have a common cause that renders them conditionallyindependent. Reichenbach incorporated his RCCP into a new probablistictheory of causation, and used it to describe a (purported)macrostatistical temporal asymmetry in analogy with the second law ofthermodynamics. The principle is significant because it posits aconnection between causal structure and probabilistic correlations,thus facilitating causal inference from observed correlations.However, RCCP has been controversial, and a number of counterexampleshave been proposed. RCCP is often seen as an antecedent of theCausal Markov Condition, which plays a central role in causalmodeling and causal inference. RCCP has also been taken to captureassumptions about the behavior of classical systems that appear to beviolated in quantum mechanics.