 Considering only binary variables, Reichenbach says in structure I, the common cause case, A and B are not individually independent of C (the probability of each is greater conditional on C than conditional on ~C), but A and B are independent of one another conditional on C and on ~C. He claims—erroneously—that these facts do not distinguish between I and II, and indeed are typical of causal structures such as II. Using an example with the structure III he writes: “For instance, the spouting of the geysers may have the effect that two clouds are formed which merge into one large cloud. Then the occurrence of this large cloud is an effect E which satisfies [the probability properties of I]” (p. 162). This is an important mistake. In structure III, representing the causal structure of the geyser cloud example, A and B are independent conditional on D, but for almost all probability distributions, A and B are not independent conditional on C and D. That is, III implies (for almost all probability distributions) that none of A, B, C, D are independent, that A, B are independent conditional on D, and that A, B are not independent conditional on C or on C and D. If the directions of edges in III are reversed, as in IV, the same relations hold, but with C and D interchanged. The direction of the causal relations between the eruption and the formation of the large cloud is thus encoded in the conditional probability relations. Reichenbach mangles the relationships in a confused passage: 