 In what follows,  Section 2  explains different varieties of the paradox, clarifies the logical relationships between them, and identifies precise conditions for when the paradox can occur. While that section focuses on the mathematical characterization of the paradox,  Section 3  focuses on its role in causal inference, its implications for probabilistic theories of causality, and its analysis by means of causal models based on directed acyclic graphs (DAGs: Spirtes, Glymour, &amp; Scheines 2000; Pearl 2000 [2009]).