[dantheman]

Definition 2 is a flawed definition, perhaps some parts of astrology are wrong, but some parts of physics are wrong, we just need more time to work out the bugs in astrology -- more experiments need to be made.

If you're interested in this problem, this is a great reference: http://plato.stanford.edu/entries/pseudo-science/

[khafra]

I think when your model consistently gives results indiscernable from random noise in its strongest application (cf. blog.okcupid.com), you can safely conclude that it's of no more value than a model selected at random from all possible models of similar complexity.