An article from Space.com does a great job debunking the parallel that Intelligent Design proponents draw between their brand of nonsense and the logic behind SETI. Apparently the ID nutjobs (my term, not that of the article) suggest that the search for extraterrestrial intelligence is concluding that if they find a complex radio signal, it must be the result of intelligence. Since one of the main arguments against ID (other than it’s stupid – again, that’s Jason’s conclusion only) – is that complexity does not imply design, as in the case of DNA, isn’t it a double standard to allow SETI to make the same sort of claim?
Instead of just saying "Uh, you’re dumb" like I would, the author here makes several important points about the assumptions the ID crowd makes, and demonstrates quite effectively that the parallel they attempt to draw with SETI simply doesn’t exist. This quote from the conclusion wraps up the argument well, but it’s worth taking a gander at the whole article.
In short, the champions of Intelligent Design make two mistakes when they claim that the SETI enterprise is logically similar to their own: First, they assume that we are looking for messages, and judging our discovery on the basis of message content, whether understood or not. In fact, we’re on the lookout for very simple signals. That’s mostly a technical misunderstanding. But their second assumption, derived from the first, that complexity would imply intelligence, is also wrong. We seek artificiality, which is an organized and optimized signal coming from an astronomical environment from which neither it nor anything like it is either expected or observed: Very modest complexity, found out of context. This is clearly nothing like looking at DNA’s chemical makeup and deducing the work of a supernatural biochemist.