Originally Posted by Freebase Dali

There is far more scientific credibility in mathematical probability than there is in speculation based on imagination... If one is given an argument whereupon one side presents no proof, but does present a mathematical likelihood to support the theory, versus an argument that presents no proof, but does present a fun idea to support the theory... I don't think it's very difficult to decide (for most reasonable people) which idea to prefer over the other, even if neither of them offers any actual proof.

I guess there would be, technically speaking, a mathematical probability for anything. But I'd say the probability for any form of life existing on another planet is undeniably higher than the probability of underground pig societies (in the conventional sense that such a label conveys).