Wednesday, 6 July 2011

It's designed if it looks designed?

Here we go again. "The Scientific Status of Design Inferences" by Bruce L. Gordon is Chapter 25 of Dembski & Licona's Evidence for God. It begins by doubting that methodological naturalism must be the necessary limit on the scope of science. With liberal use of technical terms from the philosophy of science (without citations), Gordon considers three accounts of "what it means to offer a scientific explanation for a phenomenon." These are the deductive-nomological model, the causal-statistical model, and the pragmatic model. They appear to be different ways of identifying causes that are both necessary and sufficient to explain any particular phenomenon. And they're quite interesting, though Gordon gets bogged down in the minutiae — which would be excusable if it was going somewhere useful. But as usual with intelligent design proponents, he promises much and delivers next to nothing. There's stuff that sounds a bit sciencey, but no actual science.
As William Dembski points out, drawing design inferences is already an essential and uncontroversial part of various scientific activities ranging from the detection of fabricated experimental data, to forensic science, cryptography, and even the search for extra-terrestrial intelligence (SETI). He identifies two criteria as necessary and sufficient for inferring intelligence or design: complexity and specification. Complexity ensures that the event in question is not so simple that it can readily be explained by chance. It is an essentially probabilistic concept. Specification ensures that the event in question exhibits the trademarks of intelligence. The notion of specification amounts to this: if, independently of the small probability of the event in question, we are somehow able to circumscribe and define it so as to render its reconstruction tractable, then we are justified in eliminating chance as the proper explanation for the event. Dembski calls such an event one of specified small probability.
Sounds reasonable, doesn't it? Except that it's no practical advance on saying "it's designed if it looks designed." Note the use of "somehow" — this ought to be a teaser for what's to come, but despite not-so-vague promises, we never find out how this specification is to be assessed. (Also note the inclusion of SETI in this block of things supposedly exhibiting intelligence. SETI, however, is not expecting — or hoping — to receive signals containing information, and without information there can be no intelligence.)
One of Dembski's important contributions has been to render the notion of specification mathematically rigorous in a way that places design inferences on a solid foundation.
That's a big claim to rigour and solidity, but where is this rendition? It's often parroted by Dembski's acolytes, but never delivered.
The mathematical analysis used to determine whether an event is one of specified small probability rests on empirical observations set in the context of the theoretical models used to study the domain (quantum-theoretic, molecular biological, developmental biological, cosmological, etc.) under investigation, but the design inference itself can be formulated as a valid deductive argument. One of its premises is a mathematical result that Dembski calls the law of small probability. That the design inference lends itself to this precision of expression is significant because it enables us to see that a rigorous approach to design inferences conforms to even the most restrictive theory of scientific explanation, the D-N model. In fact, even though the accounts of scientific explanation we considered were inadequate as universal theories, all three of them captured important intuitions. Furthermore, it is short work to see that rigorous design inferences satisfy the conditions imposed by all of them.
But we've yet to see the touted "precision of expression". Where are these "rigorous design inferences"? Are they anything more than "if it looks designed, it must have had a designer"? Gordon mentions "design-theoretic analysis" several times in this essay, but gives no actual examples of it (or any references). Why is this? Is it, perhaps, because such analysis has never actually been done?


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