> Re. Doug's comment. I'm not exactly sure what David meant. But one
> could argue that (1) the EMH theory as such, that is, as a theory (as
> understood among conventional economists), is not refutable by facts,
> but only by logic. The EMH is an "if X, then Y" statement. The EMH
> cannot be deemed responsible for X not holding, but only for Y not
> holding given that X holds. And that is a problem of logic (or math).
Then it's not a scientific theory. Logical consistency is a necessary but not sufficient condition for generating a good scientific theory. I'm no Popperian, but the possibility of empirical disconfirmation is a crucial characteristic of any meaningful scientific theory. If you're not interested or willing to test your logically consistent theory by evaluating evidence, you're doing quasi-theology or philosophy (which is not necessary bad, but let's call it what it is).
Miles