From the December 8, 2007 edition of George P. Dvorsky's
Blog, Sentient Developments.

The problem with 99.9 % of so-called 'solutions' to the Fermi Paradox

Non-exclusivity.

Sure everyone has a convenient answer to the Fermi Paradox, but nearly all of them fail the non-exclusivity test. While some solutions to the FP may account for many if not most of the reasons why we haven't detected signs of ETI's, they cannot account for all.

For example, take the notion that interstellar travel is too costly or that civs have no interest in embarking on generational space-faring campaigns. Sure, this may account for a fair share of the situation, but in a Universe of a gajillion stars it cannot possibly account for all. There's got to be at least one, if not millions of civs, who for whatever reason decide it just might be worth it.

Moreover, answers like the ‘zoo hypothesis,’ ‘non-interference,’ or ‘they wouldn’t find us interesting,' tend to be projections of the human psyche and a biased interpretation of current events.

Full article here:

http://sentientdevelopments.blogspot.com/2007/12/problem-with-999-of-so-called-solutions.html