Post Author: Bill Pratt

I recently wrote a series of three blog posts discussing the argument to design from analogy.  I concluded that this approach to arguing that life is designed is a live option, but that it falls short of the kind of certainty we would like the argument to have.

Philosopher of science Stephen Meyer, in his book Signature in the Cell, points out the weakness in any design argument from analogy:

The status of such design arguments inevitably turns on the degree of similarity betwee the systems in question.  If the two effects are very similar, then inferring a similar cause will seem more warranted than if the two effects are less similar.  Since, however, even advocates of these classic design arguments admit there are dissimilarities as well as similarities between living things and human artifacts, the status of the analogical design argument has always been uncertain.  Advocates argued that similarities between organisms and machines outweighed dissimilarities.  Critics claimed the opposite.

Do modern intelligent design proponents rely solely on design arguments from analogy?  No.  Meyer’s approach is to argue from DNA to design by inference to the best explanation, or abduction.  This is the dominant method used in the historical sciences such as forensic science, evolutionary biology, paleontology, geology, archaeology, and cosmology. 

Meyer explains the difference between argument from analogy and inference to the best explanation with regard to DNA and design:

But the DNA-to-design argument does not have an analogical form.  Instead, it constitutes an inference to the best explanation.  Such arguments do not compare degrees of similarity between different effects, but instead compare the explanatory power of competing causes with respect to a single kind of effect.

So what is the single effect that needs explaining?

As noted, biological information, such as we find in DNA and proteins, comprises two features: complexity and functional specificity.  Computer codes and linguistic texts also manifest this pair of properties (“complexity” and “specificity”), what I have referred to . . . as specified information.  Although a computer program may be similar to DNA in many respects and dissimilar in others, it exhibits a precise identity to DNA insofar as both contain specified complexity or specified information.

Accordingly, the design argument developed here does not rely on a comparison of similar effects, but upon the presence of a single kind of effect – specified information – and an assessment of the ability of competing causes to produce that effect.  The argument does not depend upon the similarity of DNA to a computer program or human language, but upon the presence of an identical feature in both DNA and intelligently designed codes, languages, and artifacts. 

Meyer continues his argument:

Because we know intelligent agents can (and do) produce complex and functionally specified sequences of symbols and arrangements of matter, intelligent agency qualifies as an adequate causal explanation for the origin of this effect.  Since, in addition, materialistic theories have proven universally inadequate for explaining the origin of such information, intelligent design now stands as the only entity with the causal power known to produce this feature of living systems.  Therefore, the presence of this feature in living systems points to intelligent design as the best explanation of it, whether such systems resemble human artifacts in other ways or not.

To summarize, there is specified information in DNA, and the only cause of specified information we know of is intelligent agency.  Therefore the cause of DNA is intelligent agency or design.  To refute this argument, you must demonstrate that there is not specified information in DNA, or that specified information can be caused by non-intelligent processes.  Neither of these has been done, to my knowledge, so this argument to design seems to remain valid.