 Nor is there any direct evidence for Jackson’s theory. Nobody who thinks the Republicans won’t win treats “If the Republicans win, they will double income tax” as inappropriate but probably true, in the same category as “Even Gödel understood truth-functional logic”. Jackson is aware of this. He seems to advocate an error theory of conditionals: ordinary linguistic behaviour fits the false theory that there is a proposition \(A*B\) such that \(\mathbf{p}(A*B) = \mathbf{p}_A (B)\) (1987, pp. 39–40). If this is his view, he cannot hold that his own theory is a psychologically accurate account of what people do when they use conditionals. Perhaps it is an account of how we should use conditionals, and would if we were free from error: we should accept that “If the Republicans win they will double income tax” is probably true when it is probable that the Republicans won’t win. Would we gain anything from following this prescription? It is hard to see that we would: we would deprive ourselves of the ability to discriminate between believable and unbelievable conditionals whose antecedents we think false.