Thursday, December 01, 2005

A SETI Researcher on ID

There is a standard contradiction in the work of ID proponents. On the one hand they tell us that scientists dismiss design out of hand as a legitimate explanation. Then they turn around and tell us that, actually, many scientists are already in the business of drawing design inferences. They point to forensic pathology and archaeology as examples.

A third example used by ID proponents is SETI - The Search for Extraterrestrial Intelligence. SETI researchers use radio telescopes to try to detect certain sorts of radio signals from space that would strongly indicate an intelligent cause. Most scientists consider the logic behind SETI to be sound, even if the search itself is almost certainly futile.

ID folks like to argue that their methods of design detection are merely an extension of those used by SETI. Now here comes an actual SETI researcher, Seth Shostak, to explain why that's nonsense. He writes:

The way this happens is as follows. When ID advocates posit that DNA—which is a complicated, molecular blueprint—is solid evidence for a designer, most scientists are unconvinced. They counter that the structure of this biological building block is the result of self-organization via evolution, and not a proof of deliberate engineering. DNA, the researchers will protest, is no more a consciously constructed system than Jupiter’s Great Red Spot. Organized complexity, in other words, is not enough to infer design.

But the adherents of Intelligent Design protest the protest. They point to SETI and say, “upon receiving a complex radio signal from space, SETI researchers will claim it as proof that intelligent life resides in the neighborhood of a distant star. Thus, isn’t their search completely analogous to our own line of reasoning—a clear case of complexity implying intelligence and deliberate design?” And SETI, they would note, enjoys widespread scientific acceptance.

I'm not sure if “self-organization via evolution” is really the best way of putting things, but otherwise these statements are correct.

After emphasizing that SETI researchers are not looking for complex messages embedded in the radio signals they detect from space (messages their equipment would be unable to discern), Shostak points out that they are looking not for complexity, but for artificiality:

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.

Consider pulsars – stellar objects that flash light and radio waves into space with impressive regularity. Pulsars were briefly tagged with the moniker LGM (Little Green Men) upon their discovery in 1967. Of course, these little men didn’t have much to say. Regular pulses don’t convey any information—no more than the ticking of a clock. But the real kicker is something else: inefficiency. Pulsars flash over the entire spectrum. No matter where you tune your radio telescope, the pulsar can be heard. That’s bad design, because if the pulses were intended to convey some sort of message, it would be enormously more efficient (in terms of energy costs) to confine the signal to a very narrow band. Even the most efficient natural radio emitters, interstellar clouds of gas known as masers, are profligate. Their steady signals splash over hundreds of times more radio band than the type of transmissions sought by SETI.

Shostak is making an excellent point here, but first we must correct a small error. The simple sinusoidal tones Shostak is describing are, indeed, non-complex in the everyday sense of that term. But in ID-land, most notably in the work of William Dembski, the term “complex” takes on a different meaning. Specifically it is synonymous with “low probability.” Thus, an event is complex if it has a low probability of occurring via chance or natural causes alone.

In other words, Shostak is essentially using the term “artificiality” in the same way ID proponents use the term “complexity.”

An ID proponent could claim that there is a very low probability that a natural radio emitter could produce the sort of tone Shostak describes. He might go on to argue that there is no known natural law that produces such signals with high probability, and that the tone is specified by virtue of its simple, sinusoidal pattern. It is this, an ID proponent would argue, that allows the SETI researcher to infer design.

But this leads us to the strong point Shostak is making. For how can we determine that a given radio signal is complex (or artificial)? Dembski tells us that we are supposed to do an actual calculation to determine the probability that the radio signal could be produced by chance or natural causes. This method is rather silly, since there is almost never any empirical basis for such a calculation.

The way SETI researchers actually do it is by calling upon their vast experiences with natural radio emitters. An awful lot of radio signals from an awful lot of sources have been analyzed, and not one has ever produced the dead simple tone Shostak describes. It is this experience that allows us to say that a dead simple tone is artificial.

I made the same point in a different context in my recent series of essays on probability (go here and here). There I used the example of Mt. Rushmore (a favorite of ID folks). The way we know the faces on Mt. Rushmore could not have been produced by natural causes like weathering and erosion is that we have seen the effects of those forces on countless other mountains. It is this experience, not some bogus probability calculation, that tells us Mt. Rushmore must have been designed.

Summing up: SETI researchers argue that a dead simple tone would suggest an intelligent cause based on their massive experience with natural radio emitters. ID proponents argue that DNA embodies design-suggesting patterns based on nothing at all.

Shostak concludes with a second, related point:

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.

Well said.

One other point Shostak might have made is that SETI researchers are looking specifically for intelligent agents that are similar in relevant ways to human beings. In other words, they are making assumptions about the nature of their designers, and the sorts of scientific skills and technology they have access to. Such assumptions are essential to the logic of the situation.

ID proponents, however, are quite explicit, that we can make no statement about the nature of the designer they are detecting. This is another reason why SETI arguments are based on sound logic, while ID arguments are based on ignorance and misunderstanding.


At 11:02 PM, Blogger Don Sheffler said...

And SETI is not postulating a supernatural or magical source of the signals they're looking for. Otherwise they would not even have a starting point for what patterns to expect. They'd have to resort to the Behe filter of "I'll know it when I see it." (or hear it).

At 1:44 PM, Anonymous Anonymous said...

I agree that "self-organization via evolution" is not the best way to put it because it's not very accurate.

I'd say "self-organization via the rules of chemistry and physics" or "organization guided by natural processes/forces."

This is another counter to any creationist including the ID people when they say "unguided evolution."

Well, evolution is certainly not unguided. It's guided by nature. In other words, it's guided by the rules of chemistry, physics, even math set up by "nature."

They can say that these rules were set up by God if they want, but it's not the same as the premise of ID, which is that God is a hidden dictator reaching in with his influence at arbitrary points in time to tinker with atoms and molecules...


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