Today I received an inquiry from a friend who is an atheist regarding the question of suboptimal design in nature. He was interested in learning how I would respond to “apparent instances of poor design, both in humans and throughout the animal kingdom.” He gave a few examples, “rang[ing] from technical design flaws such as the recurrent laryngeal nerve, to vestigial features such as the marsupial mole having non-functioning eyes hidden under its skin, to ‘commonsense’ features such as using the same mouth for both eating and breathing, leading to an untold number of deaths through choking.”
In response, I identified four fundamental flaws with the argument from suboptimal design in nature. Here is my reply:
Thanks for your question. It seems to me that there are several flaws with the argument from ‘suboptimal design’ in nature. For one thing, the ability to detect design does not require that the design be optimal. Windows operating systems have many design flaws – but that doesn’t make them any less designed. The argument carries the assumption that the only candidate for designer is an omnipotent and benevolent deity, but this doesn’t necessarily follow. I happen to believe in such a deity (for, in my judgment, good reasons), but I don’t believe that it logically follows from the evidence of design in biology. Even if one is a theist, I see no problem with the position that God may have acted through secondary causes. Perhaps there is some sort of intrinsic teleology built into the world, for instance, that produces the sort of complex specified information we find so abundantly in living systems.
A second problem with the argument is that it assumes that an intelligent cause would have to produce each living thing de novo. But, again, this doesn’t necessarily follow. The theory of ID (as applied to biology) asserts that there are certain features of living systems that bear hallmarks of an intelligent cause, but this does not necessarily entail a rejection of common ancestry. Perhaps there are constraints on design placed by an organism’s evolutionary history. I happen to be skeptical of universal common ancestry, for reasons that I have articulated in my writings. But it isn’t at all incompatible with ID – in fact, many of my colleagues (e.g. Michael Behe) subscribe to common descent. I’m ambivalent on the issue. I can see some defensible arguments for the idea of hereditary continuity, but I can also see severe scientific problems with it. In my opinion, many evolutionary theorists fall victim to confirmation bias here.
Third, the theory of ID does not require that everything in biology be designed. Indeed, designed artifacts may exhibit evidence of weathering – an example of this would be the once-functional vestigial lenses of marsupial moles which are hidden under the skin.
Fourth, the argument often commits what one might describe as an “evolution-of-the-gaps” fallacy. Whereas the “god-of-the-gaps” fallacy states that “evolution can’t explain this; therefore god must have done it,” the converse “evolution-of-the-gaps” fallacy states that “God wouldn’t have done it that way; therefore evolution must have done it.” It is curious that this dichotomous mode of thinking is precisely what ID proponents are often accused of. Much like “god-of-the-gaps” arguments, the “evolution-of-the-gaps” argument has to retreat with advances in scientific knowledge, as biologists uncover important reasons for the way these features have been designed. One example of this would be the once-thought-to-be-prevalent “junk DNA” in our genomes, for which important function is constantly being identified. I would argue that such design reasons or “trade-offs” are plausible for the recurrent laryngeal nerve that you mention (as well as many of the other examples that are traditionally cited). On this subject, I would invite you to read this article (and the links contained therein) by my colleague Casey Luskin.
I hope this answers your question. Feel free to respond to these remarks.