> We’d expect that the a priori odds are good, by the principle of indifference: After all, you can divvy up the possibilities as: 1) A causes B 2) B causes A 3

> We’d expect that the a priori odds are good, by the principle of indifference: After all, you can divvy up the possibilities as: 1) A causes B 2) B causes A 3) both A and B are caused by a C > If it’s either #1 or #2, we’re good and we’ve found a causal relationship; it’s only outcome #3 which leaves us baffled & frustrated. If we were guessing at random, you’d expect us to still be right at least 33% of the time. And we can draw on all sorts of knowledge to do better Generally, I'm not a fan of argumentation or logic that references the principle of indifference. Sure, if you insist on making an assumption without any prior information, there is an argument for choosing P = 1 / N. But I don't think the article needs to make sure an assumption about the prior -- it does not seem to be essential to the article's point. In statistics (and perhaps in life), it is often better to be honest about your ignorance.