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Intelligent Design Probability

December 24, 2010

A thought occurred to me that I meant to include in my last post. I highlighted the fact that evolution, probability and “intelligent” design don’t mix all that well, with ID advocates often seeming to assume that the theory of evolution implies that traits must be gained by the random mixing of genes. So if the gene sequence needed to code some trait is x long, then the argument goes that the number of attempts or mutations needed to get to this stage is k^x, where k is the number of possible gene types (hopefully my attempt at that description makes sense…).

A recent paper dispels this notion, instead providing a model whereby it takes k log(x) mutations. This is much, much smaller once the numbers get big. Instead of modelling a sequence x long which is guessed repeatedly until the “correct” combination is found, the paper models it as a a number of guesses where only the incorrect positions are tried again. This is obviously a quicker strategy than starting afresh with each guess, and mimics evolutionary processes more closely. If a given gene sequence is beneficial, it will be selected for and will be “fixed” in the population (plus or minus more mutations). Selection can then act on the remaining genes.

P Z Myers gives a good example:

To put some representative numbers on it, imagine a protein that is 300 amino acids long, made up of 20 possible amino acids, and I’m going to ask you to guess the sequence. Under the creationist model, you wouldn’t even want to play the game — it would take you on the order of 20300 trials to hit that one specific arrangement of amino acids. On the other hand, if you took a wild guess, writing down a random 300 amino acids, and I then told you which amino acids in which position were correct, you’d be able to progressively work out the exact sequence in only 20 log 300 trials, or around 50 guesses.

There are obvious problems with the model, and in reality I think this probably puts a lower bound on the expected number of trials rather than a definitive estimate, but it shows why thinking in such a simplistic model, as characterises ID advocates, is wrong.

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6 Comments leave one →
  1. Nate Moening permalink
    December 24, 2010 7:47 PM

    Interesting post. If I may, I’d like to throw some physics into the mix here with the larger creationism vs. non-creationism debate, which is not necissarily what you’re getting at with this post, but an interesting and heated debate nevertheless. In an article I recently read about Einstiein’s Theory of Relativity, the last section was titled “Theory of Relativity–A Testament to Creationism”. This struck me as odd, but the author was talking about the existance of something capable of creating the universe, based on logical observations. This exerpt from the article explains:

    “The General Theory of Relativity demonstrates that time is linked, or related, to matter and space, and thus the dimensions of time, space, and matter constitute what we would call a continuum. They must come into being at precisely the same instant. Time itself cannot exist in the absence of matter and space. From this, we can infer that the uncaused first cause must exist outside of the four dimensions of space and time, and possess eternal, personal, and intelligent qualities in order to possess the capabilities of intentionally space, matter — and indeed even time itself — into being.

    Moreover, the very physical nature of time and space also suggest a Creator, for infinity and eternity must necessarily exist from a logical perspective. The existence of time implies eternity (as time has a beginning and an end), and the existence of space implies infinity. The very concepts of infinity and eternity infer a Creator because they find their very state of being in God, who transcends both and simply is.” The full article can be found here: http://www.allaboutscience.org/theory-of-relativity.htm

    I’m not sure how related this is to your original post, but I think it is an interesting point that should be taken into consideration. Thanks for your time.
    -Nate Moening

  2. December 24, 2010 8:19 PM

    Not that related, but here we go…

    The excerpt you quote assumes the existence on an “uncaused first cause”. Why should this exist? I’ll accept that if it exists it is eternal, but why should it be personal and intelligent?

    Why should the fact that something is logically possible imply it’s existence? An elephant doing a handstand in my back garden is logically possible, but I can guarantee it’s not there.

    How does the author define eternal? For all time? In that case yes, time implies eternal. But how does space imply infinite?

    This is a passage that creates way more questions than answers and is fairly typical of attempts to use science and it’s language to provide modern takes on the ontological and cosmological arguments. I’m not hopeful about the full article, but we shall see. Maybe some bloging material for later!

  3. Nate Moening permalink
    December 24, 2010 9:07 PM

    I somewhat expected a reply like this, as anyone entering the fray of this debate should. I don’t see either side of this ongoing conflict of beliefs caving anytime soon. I see the flaws in the theory and I accept the fact that I don’t possess the ability to prove any of the implications (nor does anyone, really). I suppose it all boils down to the fact that the only people who are 100% certain of what really happened and what really exists beyond the bounds of this universe–if anything–lack the ability to tell us. I personally find some solace in the fact that there are logical implications of a creator, no matter how abstract they may be. Being somewhat agnostic, and thinking mainly in terms of logic and science, this makes it easier for me to have faith in something beyond this world. I respect that many people–including yourself–disagree strongly with these ideas and I don’t intend to start jamming my beliefs down their throats.

    Great points in your reply, I am at a loss trying to come up with a counter, and I intend to ponder this topic for a long while as I continue my education, and perhaps have some revelations about it as I do.

  4. December 24, 2010 9:08 PM

    See my latest post

  5. December 24, 2010 9:13 PM

    I certainly didn’t want to be too off-putting in my reply – I just think it’s important to think about things coherently and, most importantly, ask lots of questions about what we read. Finding articles online is good, but thereare caveats to everything we read. In this case, it’s that the author(s) are creationists using science to further a very unscientific agenda, which has to be kept in mind. It’s philosophically incoherent and doesn’t help us get anywhere.

    I don’t claim to have certainty, I like you am searching for “truth”. Nothing wrong with trying to make others agree with you, as long as it’s civil!

  6. Nate Moening permalink
    December 24, 2010 9:39 PM

    It’s not off-putting at all to me, I understand and respect that other people have views and opinions, and that I am not always right. I also understand when I’ve put my foot in my mouth by quoting a source that doesn’t really deserve the credit. I normally am very skeptical and ask many questions about information given to me, but this is a tricky topic and I suppose I wasn’t sufficiently analytical in reading this article.

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