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How Do We Get From DNA to Design?

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.

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  • Anonymous

    Define “information.”

  • According to Meyers, on page 86 of his book, information is “the attribute inherent in and communicated by alternative sequences or arrangements of something that produce specific effects.”

  • Pingback: How Do We Get From DNA to Design? | Time For Discernment()

  • Andrew Ryan

    Do rings on a tree trunk qualify? They give us information on the age of the tree; they are produced WITHOUT an intelligent agency. If tree rings don’t qualify, can you explain why not?

  • Andrew Ryan

    How’s about the information that meteorologists gather from the atmosphere? That is produced naturally, and gives us very specific information about tomorrow’s weather. Is this a counterexample to Meyer’s claim that information always has an intelligent source?

  • Boz

    What do you mean by ‘specifity’, or its opposite, ‘general’ ?

    What do you mean by ‘complex’, or its opposite, ‘simple’ ?

    With both of these ideas, how is the Eye Of The Beholder problem avoided?

    Is a mile long or short ?

    Is a triangle complex or simple?

    is 56,345,839 specific or general ?

  • Andrew_EC

    Yeah, this is a particularly silly definition by Meyer because it not only obviously *includes* naturalistic sources of “information” (e.g., tree rings, mushrooms that grow on the northern-facing side of trees, arrangements of stars used for navigation, and so on and so on), but it would *exclude* some intentional acts by which humans communicate information. Just for fun:

    Andrew R: “How many people are reading this thread?”

    Andrew EC: “4”

    Andrew R: “Neat. Hey, how many children do you have?”

    Andrew EC: “4”

    Andrew R: “Very interesting! How old is your youngest?”

    Andrew EC: “4”

    Andrew R: “Really? Me too! Hey, I’ve got to go, but what time today, Eastern Standard, can you be back online to chat?”

    Andrew EC: “4”

    It’s kind of trivial, of course, but since I’m not communicating an “alternative sequence” to you — I’m just repeating “4” over and over again — it seems to me that by Meyer’s definition I haven’t actually communicated any information to you, even though I pretty clearly have.

  • I was asked for a definition of “information,” not “specified information.” There’s a big difference. Meyer never argues that all information must come from an intelligent source. Please re-read the blog post to see this.

    Also, it is interesting to note that Meyer gets that definiion of information from a dictionary, so it’s not his specially crafted definition of the word.

  • With respect to DNA, “specified” has referred to the fact that the “ability of the cell to build functional proteins depends on the precise sequential arrangement of the bases in DNA.”

    “Complexity” refers to the fact that “sequences of nucleotide bases in DNA and the sequences of amino acids in proteins are highly improbable and, therefore, have large information-carrying capacities.” This is also referred to as Shannon information.

    I don’t see how either one of these suffers from the Eye-of-the-beholder-problem.

    As I’ve said before, if you really want to understand all of this, I would highly recommend Meyer’s book.

  • Boz

    Those two quotes are just properties of DNA, they are not definitions of words.

    So, DNA has “complexity” and “specificity” (and therefore has CSI) because it is defined to be so.

    This does not increase our knowledge or understanding.

    This is just a silly little game, modifying the definitions of words, to achieve a chosen outcome.


    Is there an actual definition of Complex or Specific in that book? The dictionary definitions of Complex and Specific do have the Eye-of-the-Beholder problem.

  • Boz,
    I was trying to be helpful by applying the conditions of specification and complexity to DNA, since I thought you wanted to understand Meyer’s argument. Specification refers to sequential arrangement necessary for function and complexity refers to improbabilty and thus information-carrying capacity.

    Again, just buy the book and read it.

  • Anonymous

    I’ve read the book. It’s rubbish.

  • Anonymous

    It is well-demonstrated that Shannon information can arise naturally; e.g., gene duplication. So again, Meyer’s argument is trivially self-refuting.

  • He never argued that Shannon information can’t arise naturally. Are you sure you read his book? Because you are accusing Meyer of saying things he did not say.

  • Ktisis

    Duplication does not increase the amount of actual information, just as buying two identical copies of today’s newspapers means that you have twice as much news. New information must be new information, not merely copies. Otherwise, simple reproduction or even mitosis could be credited with creating twice as much information. Nonsense.

  • Ktisis

    Tree rings are only meaningful because they are interpreted by an intelligent agency (us). Our ability to gain knowledge of something (such as reading the barometer to predict weather) is an altogether different issue to the issue of genetic encoding-decoding of specified information. Also, you are assuming that the process that creates tree rings was not intelligently designed ultimately in the first place, but that is another topic. Erosion patterns can tell me a great deal about the past history of an area, but that is only because of a tremendous database of understanding that we already possess about such processes.

  • Andrew Ryan

    Well if you’re going to make that argument you can say that one cannot prove that anything naturally occurring isn’t being caused by an invisible agent. It’s an unfalsifiable assertion – no matter what we learn about the natural processes that create, say, snowflakes, rain or tree rings, you can still shrug and say that some supernatural force is ultimately responsible.

    That’s completely irrelevant to the fact that we understand the natural processes that creates those things; it doesn’t affect that tree rings are a clear example of naturally arising information. We can interpret that information, but that information would still be there if we weren’t here to interpret it.

    You might as well say that without us to interpret DNA, then you’ve just got chemicals operating on natural processes.

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