ID and SETI

One of the standard arguments we hear from ID proponents is the analogy between SETI (Search for Extra-Terrestrial Intelligence) and ID. Their argument is that SETI researchers use the same basic premises and inferences that ID does in the search for radio signals from alien civilizations. It's an argument with a superficial appeal to it. After all, SETI researchers have to have some means of distinguishing between signals that are a result of natural processes (pulsars, for example) and signals that are the result of intelligence. The reality, though, is that the means of searching for intelligence in radio signals is highly non-analogous to what ID advocates propose for biology. And that is the point of a new article by Seth Shostak, a researcher with the SETI Institute.

Shostak points to one of the primary distinctions between ID and SETI right off the bat: ID advocates base their inference on complexity - the argument being that some biological systems are too complex to have been made by natural processes - while SETI researchers are looking primarily for artificiality:

In fact, the signals actually sought by today's SETI searches are not complex, as the ID advocates assume. We're not looking for intricately coded messages, mathematical series, or even the aliens' version of "I love Lucy." Our instruments are largely insensitive to the modulation--or message--that might be conveyed by an extraterrestrial broadcast. A SETI radio signal of the type we could actually find would be a persistent, narrow-band whistle. Such a simple phenomenon appears to lack just about any degree of structure, although if it originates on a planet, we should see periodic Doppler effects as the world bearing the transmitter rotates and orbits.

And yet we still advertise that, were we to find such a signal, we could reasonably conclude that there was intelligence behind it. It sounds as if this strengthens the argument made by the ID proponents. Our sought-after signal is hardly complex, and yet we're still going to say that we've found extraterrestrials. If we can get away with that, why can't they?

Well, it's because the credibility of the evidence is not predicated on its complexity. If SETI were to announce that we're not alone because it had detected a signal, it would be on the basis of artificiality. An endless, sinusoidal signal - a dead simple tone - is not complex; it's artificial. Such a tone just doesn't seem to be generated by natural astrophysical processes. In addition, and unlike other radio emissions produced by the cosmos, such a signal is devoid of the appendages and inefficiencies nature always seems to add - for example, DNA's junk and redundancy.

Jason Rosenhouse has more on this matter on Evolution Blog.