No correlation without causation. This is the most compact formulation of Reichenbach's Common Cause Principle (RCCP). More explicitly RCCP is the claim that if two events A and B are correlated, then either A and B stand in a causal relation, R_cause(A, B), or, if A and B are causally independent, R_ind(A, B), then there is a third event C, a so-called Reichenbachian common cause that brings about the correlation by being related to A and B in a specific manner spelled out in the following definition, first given by Reichenbach (1956): Event C is called a (Reichenbachian) common cause of the correlation
(1)    � 0A0;p(A ∧ B) − p(A)p(B) > 0
if the following conditions hold:
(2)    � 0A0;p(A∧B|C) = p(A|C)p(B|C)
(3)    � 0A0;p(A ∧ B|C^⊥) = p(A|C^⊥)p(B|C...