While I generally support the various SETI projects, it seems to me they have one flaw - their "null hypothesis" (hope I'm using the right terminology) doesn't prove anything very interesting.

Compare SETI to the Kepler space telescope, which will be launched to detect statistically-significant numbers of transits of earth-sized planets across the face of the planets' parent stars. The null hypothesis for Kepler is that it doesn't detect any (or very many) earth-sized planets during its mission. This outcome is almost as interesting scientifically as the outcome where it detects planets - it means those planets aren't out there in very large numbers, and we would have to rethink our ideas on solar system formation, and the likelihood of extrasolar life.

Proving the null hypothesis through SETI, by contrast, doesnt' prove that ETI is not out there, but only that no ETI is communicating in the way we expect from the places we expect at the times we expect. That knowledge does not get us very far for all the millions being put into it.

No real solution to this, I guess. SETI will either be considerable wasted money and effort, or the most profound discovery in scientific history.