The Inevitability of Evolution (Part I)

PERHAPS THE SECOND-MOST IGNORANT of the common objections to the theory of evolution (after the ever-popular “Why are there still monkeys?”) involves some kind of objection based on the imagined “odds” against this or that biological feature appearing “completely at random.” The best known general form of this objection is presented by the Discovery Institute, a well-funded collection of creationists who pretend to offer scientific opposition to evolution.

In response to the question What is the theory of intelligent design? they offer this: “The theory of intelligent design holds that certain features of the universe and of living things are best explained by an intelligent cause, not an undirected process such as natural selection.” Whatever the Discovery Institute may say about this, it’s nothing but a claim that evolution is far more improbable than their conjectured designer.

This kind of argument — which is essentially saying “I don’t believe it!” — could be employed against more than evolution. A creationist could look at the current totality of English history, or the biosphere, or whatever, and impulsively exclaim that it’s “impossible” for such to have occurred without outside guidance. But is it really?

If England is impossible, so of course is the rest of human history. So are you, because the innumerable events leading to your conception are vast beyond comprehension. Everything is impossible to such a mentality. At what point does reductio ad absurdum intervene to put an end to this nonsense? “Never,” replies the creationist. “Prove I’m wrong!” Thus it appears that we need this series of articles.

There are several variations of the argument that the odds are against evolution, all of them fallacious. Some formulations involve different fallacies, some involve them all. This series of articles will consider a few of them.

The first fallacy is “collapsing the continuum.” The usual application involves a computation of the supposed odds against the happening of some sequence of events. The fallacy consists of wrongly treating the entire sequence of events as if it were one single event.

For example, let us consider the odds against, say, tossing a coin 100 times and getting it to turn up “heads” every time. Of course, the chance of getting some string of results — any one at all — is 100%. But the chance of getting 100 heads in sequence, or any specific string of coin tosses involves an exponential computation — one chance in two for the first toss, then the same thing for the next, etc. At the end of the sequence, the likelihood of a specific outcome is so minuscule that it’s declared to be “virtually impossible.” [The actual odds against tossing 100 heads in sequence are 2100, or approximately 1.27 times 1030.]

However, at any step along the way the chance of getting heads on the next toss is one out of two, or 50%. So if you had already enjoyed an improbable sequence of tossing heads, the chance of success for the next toss is still 50-50. Confusing the odds for each step (which are always 50-50) with the odds for the entire sequence (1 in 1.27 times 1030) involves the fallacy of collapsing the continuum.

Let’s make it more complicated than heads or tails. Consider a deck of cards. Each shuffle of a deck of cards has an outcome which is one in 52! (That’s 52 factorial, which is 8.06581752 times 1067.) It’s a huge number, which can be a metaphor for the odds (quite unknown) against our presently-existing biosphere. For comparison, the estimated number of stars in the universe is “only” 1021. Source: this NASA webpage.

By comparing those exponents we can see that the odds against any particular card shuffle are truly beyond astronomical. Yet, if you go ahead and shuffle a deck … ta-da There it is. You’ve obtained a virtually impossible outcome.

The point of the card-shuffle example is not that our particular biosphere isn’t unlikely, because it is. It’s just that whatever biosphere gets produced will be equally unlikely. Ours is no more unlikely than any other. If you went back to 4 billion years ago and started the whole thing all over again, you’d probably end up with a totally different mix of species, none of them exactly like what we have now. But this particular shuffle of the cards is ours. We’re unique. Never to be repeated. Irreplaceable. Priceless. This is why — contrary to the endlessly repeated claims of the creationists — the evolutionary point of view places a far higher value on humanity than one where we could be wiped out and started up again on a whim.

One can, if so inclined, see the hand of Providence (excuse me, the Intelligent Designer) in the outcome. Or one may decline such speculations, because each step along the way is a natural event, and the outcome is therefore every bit as natural as its component events. There’s no scientific answer to such questions. But there’s always Occam’s Razor.

Similarly, the odds against the history of England being what it has been are probably even greater (I wouldn’t even guess at how to quantify that). It wouldn’t be repeated the same way, even if it could be started all over again. It happened, quite naturally, day by day. In retrospect, the sequence that occurred is improbable, sure, but no more than any other that might have resulted; and despite the “odds” against it, there’s nothing impossible or miraculous about any of it.

The biggest problem with these computations (coin tosses, card shuffles, English history, or the biosphere) is that if you take all the events that ever happened and then whomp up some kind of monster mathematical result by stringing all the steps together, then you miss the key point: each step along the way is mathematically on its own! It’s an error to assign the characteristics of the entire sequence to an individual step. For further insights, see the Gambler’s Fallacy.

So that’s the first fallacy: assuming the entire sequence is all one step, which we’ve named collapsing the continuum. All creationists’ arguments that involve this fallacy are worthless. Evolution works. You can bet on it.

In Part II of this series we will consider another fallacious “odds” argument used by creationists: thinking small, or failure to appreciate the scale of things.

Copyright © 2009. The Sensuous Curmudgeon. All rights reserved.

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23 responses to “The Inevitability of Evolution (Part I)

  1. I rather enjoyed reading all of this. I do howerver disagree with you. I would like to know why you bielive the ideas of other men worthless when the Theory of evolution to this day is just that, a theory. There are still many wholes and although you attempted to answer the quistion on how impossible the odds are that evolution occured. What your saying is that after enough amount of attempts a certain thing can happen, such as tossing a coin 100 times in the air and having it land on heads 100 times in a row. The problem is, every time it fails whether it is on attempt 5 or attempt 95, you have to start all over again. Thus the odds still remain the same.

  2. Curmudgeon,
    I enjoyed reading your …Part I. However your logic is badly flawed. When it comes to living creatures if you fail to get a head, the thing dies and you have to start all over. And in the case of a basic living cell, you need to get 200 heads in a row to make it work. Just one tail and the thing dies and…well start all over. Besides even Richard Dawkins admits that he doesn’t know how life began. If it can’t start by itself, it can’t evolve. Elementary my dear Watson.

  3. “And in the case of a basic living cell, you need to get 200 heads in a row to make it work.”

    No. Not at all. Read Part III. Besides, 200 heads in a row is virtually inevitable, if there are a billion years to work with, and billions of interactions happening every minute within every cubic foot of sea water. Not a problem, even if it were necessary.

  4. Ron Vincent says that Dawkins doesn’t know how life started. But reading your articles makes me feel that you do know how it started, which is not necessarily arrogant I think. The mechanisms and structures that make up living things (whatever they are exactly) have supposedly been created by chance and have persisted because they enlarged chances of survival. My point would be that even though the biological complexity of the origins of life is overwhelming, your statement that it is inevitable for an evolutionary system to be created (because of your explanations in these 3 articles) seems to be sufficient. I don’t see the problem. Your reasoning is solid enough, and I think it is not necessary to be a biologist to explain life.

  5. I guess I should comment that I don’t think you think you know for a fact how life started but have an idea about it. But still, I think it’s an idea waiting to be spoken. Especially the ‘inevitability’ part of it.

  6. After reading your articles again I see that I might have misunderstood what you mean by the ‘inevitability of evolution’. What exactly do you think is inevitable? In my opinion it might be inevitable that you get an evolutionary-like chain of events from “dead” material, as long as the material is partly free to move around.

  7. Jonathan asks: “What exactly do you think is inevitable?”

    However life starts — which is an organic chemistry issue — once there is life that replicates with frequent copy errors, and this happens in an environment that changes from time to time, evolution is inevitable.

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  10. So, you think that tossing a coin heads 200 times in a row comes close to a cell puting it-self together and forming complex life with intelligence? You compare the odds of macro-evolution argument with “why are there still monkies”? Let’s talk real odds here. Try tossing a coin heads 1000 times in a row and do this at least a million times. Maybe then, we can discuss the possibility that Proteins formed from all left handed amino acids in the right order, DNA and RNA formed (I think RNA requires right handed sub. . .. . whatever), a self replicating cell comes together, millions of mutatations adding information to DNA of cells, cells forming together until we have complex life forms, more mutations and more complexity, intelligence is formed from monkey mutations, and all of this happened in only 4.5 billion years or so.

  11. Dan says: “So, you think that tossing a coin heads 200 times in a row comes close to a cell puting it-self together and forming complex life with intelligence?”

    No. Keep reading.

  12. What are the odds of a believer in Retrospective Astonishment showing up on your blog to use Retrospective Astonishment to argue against your demolition of the Fallacy of Retrospective Astonishment all by chance?

    Vanishingly slim.

    Ergo, it is a miracle!

  13. Longie says: “Ergo, it is a miracle!”

    Of all the gin-joints in all the towns in all the world, he walks into mine.

  14. tjc436atgmailcom

    Thats assuming that the entire abiogenesis and evolutionary sequence was based on chance, we know at least with evolution this is not true.
    In evolution the mutations are random, but not the selection. Try running your coin toss experiment with selection, you throw away all the results you dont like (the bad mutations) and only keep the good ones. Very quickly you will have 1000 heads in a row. Assuming evolution is a unbroken sequence of perfect mutations and therefore improbable is a fallacy in of itself.

  15. tjc436atgmailcom

    As for abiogenesis, try this experiment. Just have millions of coin tossers, you will soon get a sequence of a thousand heads in a row, without selection. Remember there was not just one molecule, there are billions of them. While the probability of a certain person winning the lottery is calculated to be very small, we know it is certain that at least someone WILL win the lottery, every day.

  16. tjc436atgmailcom, that’s taken care of in Part III

  17. Great article. I also enjoyed the comments from the morons too!

    Keep up thegood work. I also enjoyed your insulin article on

  18. I just posted a follow-up article addressing the “big tent” concern that several have expressed.

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