The design debate: why evolution succeeds where the teleological argument fails – Part 4
Criticisms of Evolution
Despite the tremendous strength of evolution theory, there are those that contest the its validity as an explanation for living things. But to start, it is important to note that this challenge tends not come from mainstream biologists, but rather from a minority of biologically educated scientists, as well as from theologians and writers. Their arguments typically come in one of two forms.
The first common objection is that biological structures are too improbably complex to have ever arisen by chance. Evolution, it is argued, depends upon luck because the process that generates variation in living things – mutation – occurs randomly. Thus, creationists argue that evolution cannot be responsible for the ordered and complex nature of living things. A classic thought experiment used to support this stance is the smashed watch analogy. This is conducted by imagining a watch (an object with all the characteristics of design) that has been completely disassembled, with its parts scrambled inside a bag. No matter how much you shake the bag, the random process of bumping these pieces into one another will never cause them to re-assemble into the orderly form of that complex watch. Thus, proponents of creationism argue that order cannot come from randomness, and evolution (which they call a random process) cannot have produced ordered, complex life.
I am willing to accept the former assertion; it does seem unlikely that a random, chaotic force could ever produce an ordered and complex object. However, I dispute the subsequent claim that this impossibility applies to evolution. I think that this criticism is indicative of a misunderstanding about how evolution operates. There is certainly a random component to evolution; mutations do tend to occur regardless of how they might affect an organism or its descendants. But it is inaccurate to say that evolution itself is a random process, because mutation is only a part of the picture. The other part of the equation, natural selection, is decidedly non-random, and it provides a directional agent that acts on the consequences of random mutation. Like a ratchet, selection ensures that evolution will tend to develop traits towards more adaptive, and often more complex, forms. While it is certainly unlikely that a random process such as mutation could ever result in the sudden composition of an entire watch, this feat is made feasible by natural selection, which guides this process of assembly one step at a time.
In this issue, my defense of evolution gains support from a computer program made to test whether or not evolution can, in fact, assemble a functional watch (see http://www.youtube.com/user/cdk007#p/a/F626DD5B2C1F0A87/0/mcAq9bmCeR0 for a much fuller account than I can provide here). This computer simulation began with the disassembled parts of a watch – gears, hands, a ratchet, and a spring – which were themselves mutable in order to allow for variation. A genetic algorithm was introduced which randomly combined these pieces and selected for whichever combinations were most effective at telling time. These successful variants were then replicated, with mutation, into the subsequent generation. In its very first generation, these simulated watch-organisms were indeed very simple. The products of chance alone, the best were mere pendulums consisting of a gear attached to the end of a hand. But as each subsequent generation passed, selection was allowed to operate. And after approximately 800 generations, this computer simulation had given rise to a functional watch comprised of 14 interconnected pieces, and with hands able to tell time accurately to the sub-second. This computer simulation demonstrates that though mutation is random, and therefore unlikely to produce purposive, ordered complexity, the same is not true of evolution as a whole. Selection, by acting on variation, ratchets this process forward, and allows evolution to act, quite literally in this case, as a blind watchmaker.
The second prototypical argument made against evolution is that of irreducible complexity. The basis of this objection is that, in addition to being complex, biological structures are comprised of interacting parts that depend on one another to function. According to evolutionary theory, biological structures evolve one step at a time, with each step being more adaptive than the previous. But if the parts of a structure are interdependent in their overall function, then they are useless until the entire structure has been formed. So how can such structures have evolved? According to proponents of intelligent design, they must not have, and the presence of irreducibly complex surely refutes evolution.
Perhaps the most famously cited example of an irreducibly complex structure is the eye. Creationist Jonathan Sarfati, for instance, has insisted that its many complex parts, such as the lens, iris, and transparent humor, each rely on one another to produce vision, and thus the eye could not have evolved one part at a time. This claim, however, is simply untrue. The fact of the matter is that the evolution of the eye is well understood by biologists today. Over the past two decades, numerous biologists have studied the origin of the vertebrate eye, and have been successful in mapping out its evolution via several functional, intermediate stages (see http://en.wikipedia.org/wiki/Evolution_of_the_eye for the details of this interesting research). With this evidence in hand, modern science has been able to debunk the notion that the eye is irreducibly complex.
Of course, proponents of intelligent design have pointed to other biological phenomena, too, as cases of irreducible complexity. Michael Behe, for instance, insisted that the blood clotting pathway, and the system of proteins that power the bacterial flagellum, are both irreducibly complex. However, plausible evolutionary pathways for the evolution of both of these have been proposed. And given the success of modern biology in resolving similar questions, I see no reason to doubt that definite answers about the evolution of these two phenomena will soon be found.
As the argument over the irreducible complexity of the eye demonstrates, creationists have tended to prey upon gaps in the knowledge of current biology. They insist that whenever our current biological understanding is unable to completely explain a phenomenon, it is evidence that God must have done it. The trouble with this sort of argument is also the resounding strength of scientific progress: it never stands still. Biologists are continually explaining more and more about the natural world in natural terms; the gaps in our knowledge are constantly closing.
For reasons such as this, the creationist arguments of irreducible complexity and of the inability of evolution to produce order have been rejected by the scientific community at large – and rightfully so. These arguments do not shed any real doubt on the ability of evolution to explain the ordered complexity of living things, and they do not breathe any new life into the teleological argument. Evolution has succeeded, while the teleological argument has failed.
Evolution as the Designer
Bearing these facts in mind, I believe that recognizing evolution as the designing force behind life is valuable, first and foremost, because the truth is important. The very point of scientific investigation is to gain a better understanding of the phenomena we observe around us. We are only doing this properly if our attempts lead us to form accurate beliefs about the natural world. The fact that both evidence and logic point to evolution as an incontrovertible explanation for the ordered complexity of life ought to therefore be enough for it to garner our acceptance.
This aside, I believe that accepting evolution is important because it informs us about the nature of living things. As Jean-Paul Sartre illustrated with his paper-knife analogy, the purpose of an object is derived from the intention of its creator. When a paper-knife was created by a human designer, it was intended to be used for opening letters. Consequently, such is the purpose of this item. But as reason and biological evidence instructs us, this analogy does not apply to living things. The order and complexity that we see in life is the not the product of deliberate design, but is instead the result of evolution, a natural process that operates without intention. As a result, we cannot derive any purpose from the mindless natural forces that are responsible for our “design”.
This is not a scientific principle, mind you, but I think it is a valuable philosophical lesson. By supplanting the teleological argument, evolutionary theory refutes the notion of telos. It reveals to us the absence of a pre-determined end or cosmological goal for living things. And thus, I believe evolution instructs us that purpose and direction in life is our own to make.
References and Further Reading
(2011, April 5). Evolution IS a Blind Watchmaker [Video file]. Retrieved from http://www.youtube.com/user/cdk007#p/a/F626DD5B2C1F0A87/0/mcAq9bmCeR0
Behe, Michael. Darwin’s Black Box. New York: The Free Press, 1996.
Bergman, Jerry. 2005 “Are ‘defective’ knee joints evidence for Darwinism?” Papers 19 (1): 107-112.
Dawkins, Richard. “Creationism: God’s Gift to the Ignorant.” The Times May 2005.
Dawkins, Richard. “Introduction: the Illusion of Design.” Natural History Nov. 2005.
Dawkins, Richard. The Blind Watchmaker. New York: W.W. Norton & Company, Inc., 1986.
Dawkins, Richard. The God Delusion. Toronto: Bantam Books, 2006.
Dawkins, Richard. The Greatest Show on Earth. Toronto: Free Press, 2009.
“Evolution of the Eye.” Wikipedia. Wikimedia, 28 03 2011. Web. Retrieved 4 April 2011, from http://en.wikipedia.org/wiki/Evolution_of_the_eye
Fernald, Russell. 1997. “The evolution of eyes”. Brain and Behavioural Evolution 50 (4): 253–59.
Hume, David. “Dialogues Concerning Natural Religion.” Online Reader. Project Gutenberg, 20 Jun. 2009. Web. Retrieved 29 Mar 2011, from http://www.gutenberg.org/catalog/world/readfile?fk_files=1456362
“Irreducible Complexity.” Wikipedia. Wikimedia, 29 03 2011. Web. Retrieved 26 Mar 2011, from http://en.wikipedia.org/wiki/Irreducible_complexity
“Intelligent Design.” Wikipedia. Wikimedia, 29 03 2011. Web. Retrieved 28 Mar 2011, from http://en.wikipedia.org/wiki/Intelligent_design
Lloyd, Geoffrey. Early Greek Science: Thales to Aristotle. New York: W.W. Norton & Company, 1970.
Lloyd, Geoffrey. Greek Science After Aristotle. New York: W.W. Norton & Company, 1973.
Sarfati, Jonathan. “Irreducible Complexity.” Refuting Evolution 2000. Web. Retrieved April 5 2011, from http://creation.mobi/article/3287/
Sartre, Jean-Paul. “Existentialism Is a Humanism.” Existentialism from Dostoyevsky to Sartre 1989. Web. Retrieved 7 Apr 2011 from http://www.marxists.org/reference/archive/sartre/works/exist/sartre.htm
“Summa Theologica.” Wikipedia. Wikimedia, 29 03 2011. Web. Retrieved 3 April 2011, from http://en.wikipedia.org/wiki/Summa_Theologica
“Teleological Argument.” Wikipedia. Wikimedia, 28 03 2011. Web. Retrieved Mar 30 2011, from http://en.wikipedia.org/wiki/Teleological_argument
“Watchmaker Analogy.” Wikipedia. Wikimedia, 08 03 2011. Web. Retrieved Mar 29, 2011, from http://en.wikipedia.org/wiki/Watchmaker_analogy