SETI vs ID

On December 1, SETI (Search for Extra-Terrestrial Intelligence) researcher Seth Shostak posted <a href=http://www.space.com/searchforlife/seti_intelligentdesign_051201.html>this brief essay</a>. It's purpose was to dispel the myth that the techniques proffered by ID folks for the purpose of detecting intelligently-caused signals bear any resemblance to those used by SETI. (William Dembski in particular is fond of making this comparison). Shostak made two especially important points. First:

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. (Emphasis in original)

There's another hallmark of artificiality we consider in SETI, and it's context. Where is the signal found? Our searches often concentrate on nearby Sun-like star systems -- the very type of astronomical locale we believe most likely to harbor Earth-size planets awash in liquid water. That's where we hope to find a signal. The physics of solar systems is that of hot plasmas (stars), cool hydrocarbon gasses (big planets), and cold rock (small planets). These do not produce, so far as we can either theorize or observe, monochromatic radio signals belched into space with powers of ten billion watts or more---the type of signal we look for in SETI experiments. It's hard to imagine how they would do this, and observations confirm that it just doesn't seem to be their thing.

I provided some further commentary on this article later that day in <a href=http://evolutionblog.blogspot.com/2005/12/seti-researcher-on-id.html>this blog entry</a> over at <a href=http://evolutionblog.blogspot.com>EvolutionBlog</a>. I pointed out that as much as I liked Shostak's article, I felt he had made a small error that would permit people like Dembski to weasel his way out.

Shostak, you see, used the term “complexity” in it's everyday sense. In other words, he was viewing “complex” as the opposite of “simple.” But in ID fantasy land “complex” means something different. When used by people like Dembski, the word is meant to refer to phenomena that are improbable when viewed as the result of chance or natural causes alone. This distinction, I felt, would allow Dembski to argue that what Shostak was referring to as “artificiality” falls under the rubric of what Dembski calls “complexity.”

In other words, he could argue that the very things that alerted Shostak to the presence of artificiality (not produced by a natural source), were the same things that would alert Dembski to complexity (something very improbable without the input of intelligence).

As I predicted, Dembski took this approach when <a href=http://www.uncommondescent.com/index.php/archives/541>he replied</a> to Shostak the following day:

But in fact, my criterion for design detection applies to the very signals that Shostak's SETI Institute is looking for. Yes, as narrow bandwidth transmissions, the signals are simple to describe. But they are difficult for purely material processes to reproduce by chance. So we have simplicity of description combined with complexity in the sense of improbability of the outcome. That's specified complexity and that's my criterion for detecting design.

More recently, Casey Luskin parroted <a href=http://www.evolutionnews.org/2005/12/dembski_responds_to_antiid_art.html>the same defense</a>.

Now, this answer is plainly inadequate even if we were to accept Dembski's musings about detecting design. In his world a probability calculation is required to establish that something is complex. And specification is supposed to be something more rigorous than “simplicity of description.” So until Dembski fills in those details, it is difficult to take seriously his claims here.

But there is a more serious objection, and it is one I also made in my original blog entry. The point of Shostak's argument lies not in some semantic distinction between “artificiality” on the one hand and an idiosyncratic view of “complexity” on the other. It is that SETI researchers have a firm basis in experience for concluding that the sort of simple tones Shostak describes could not be produced naturally. It is that experience, and not some back of the envelope probability calculation, that provides the foundations for SETI's work.

To use another favored example of ID folk, we know that Mt. Rushmore is not the result of weathering and erosion because we have seen the effects of those forces on countless other mountains. That is what alerts us to the fact that Mt. Rushmore represents something requiring a special sort of explanation. But no one in his right mind draws that conclusion from a probability calculation.

It is precisely this experience that Dembski lacks in forming conclusions about what evolution can and cannot produce. In drawing conclusions about what evolution is likely to produce in the course of four billion years, we have only one example to look at. This simple fact exposes the folly of trying to discuss the probability of a flagellum or a blood clotting cascade. It would require God-like knowledge of natural history to carry out these sorts of probability calculations. And that is why Dembski blathers about mathematics when he is trying to impress people with how rigorous his work is, but quickly retreats to intuitive arguments when pressed for details. It is why his one example of an actual probability calculation, for the bacterial flagellum, in Section 5.10 of No Free Lunch, was easily seen to reside upon a mountain of false assumptions.

Dembski in particular is fond of arguing that scientists draw design inferences all the time (in SETI, forensic pathology, and archeology, for example). Typically he tells us this after bemoaning the fact that scientists simply dismiss design out of hand as a legitimate explanation. But the point made here applies to those other branches of science Dembski mentions. In every case where scientists draw actual design inferences it is based on extensive background knowledge of the relevant natural forces and the sorts of designers whose action is being hypothesized.

ID folks refuse to address this point, with good reason. It is obvious and fatal to Dembski's entire approach. It is not that Dembski's arguments are currently in a preliminary form, but with some tweaking might be ready for prime time. It is that his whole method is fundamentally and irretrievably flawed.