One of the major scientific critiques of theistic evolution offered by the authors is that the theory of evolution does not include mechanisms with adequate creative power to explain the complex and diverse biosphere. Therefore, they say, theistic evolutionists inappropriately attempt to reconcile Christianity with an inadequate scientific theory.
To assess the creative power of evolution, the authors ask, in effect, “What is the probability that random mutations, as proposed by the theory of evolution, could account for the existence of all the biomolecules, such as proteins, that are necessary for life?” In chapter 3, Matti Leisola writes: “Twenty amino acids are the building blocks of the proteins present in all living organisms, from bacteria to humans. The average protein is about 300 amino acids in length, more precisely, 267 for bacterial and 361 for eukaryotic proteins. These 300 amino acids can be ordered in 20300 (10390) different ways.” (p. 150-151) Using a multitude of detailed examples, the various authors calculate the enormous number of combinations of amino acids that are possible. They show that the fraction of those combinations that are functional is a vanishingly small number. To illustrate the argument, they offer examples such as bike locks, Shakespeare, and language. Hence, the probability that random mutations, even those starting from a known functioning biomolecule, could result in a complete set of the necessary biomolecules is effectively zero.
This argument is repeated in many different ways but the underlying principle is always the same. A probability of life based on the number of possible combinations of the building blocks of life is zero. Therefore, the theory of evolution has inadequate creative power to explain life.
I would suggest that the authors are considering the wrong question. It is well known that a posteriori probabilities are notoriously tricky. In evolution, we only know the a posteriori result and any probability must be treated with care. Dealing with this issue involves teleology which will be discussed in future posts.
The most important reason why this is the wrong question is that valid probabilities cannot be calculated, particularly using combinations, if the possible combinations aren’t all equally probable, or nearly so. In dealing a deck of cards, this is accomplished with a reshuffle before dealing each hand. In evolution, there is no reshuffle. Instead, there is active feedback at every generation that influences which combinations will continue to be pursued. With this feedback, probabilities can only be assessed if all known feedback processes can be identified and evaluated in detail. This cannot be done for evolution. The mutation processes we observe in nature are not just simple nucleotide or amino acid changes but large-scale changes such as chromosomal crossover in gamete formation, horizontal gene transfer, transposons, retroviruses, and many more, and most likely some we have yet to identify. Survival provides feedback at each generation about which combination will be sustained. As a result, probabilities are very weak arguments for or against the theory of evolution.
Combination approaches to probability are known to scale exponentially with the number of components. This means, as in the quote above, that even average sized proteins involve an extremely large number of possible combinations. It can be shown mathematically that when feedback exists, probabilities scale much more slowly, perhaps as a power law or even logarithmically, depending on the type of feedback. This changes the outlook from impossible to the realm of possibility. This is the case for evolution. When the feedback from natural selection at each generation is taken into account, the probabilities no longer scale exponentially. The claim that evolution does not have the requisite creative power is not compelling.l.
It is nevertheless a mind-boggling claim to think that today’s diversity of life could ever have come from a simple population of primitive life. The right question to ask is not about the probabilities of evolution but to ask about evidence of what actually did happen. This is the topic of other claims in the book that we will discuss in future posts.