The eye, as I noted here earlier this week, has traditionally been admired as powerful evidence of design in the natural world. And for good reason. While biology is full of fantastically adaptive, fine-tuned, designs, it seems that vision systems must be somewhere near the top of the list. But Professor Nathan Lents insists this is all wrong and, in fact, the human eye is nothing less than a powerful refutation of design.

In centuries past the human vision system was admired for features that we take for granted today. But just because a feature is obvious does not mean it cannot tell us something about its design. Such features were highlighted three hundred years ago by the leading naturalist John Ray. The pupil, Ray noted, dilates and contracts in dim and bright conditions, respectively. The incoming light passes through the lens of the eye, and so is inverted at the retina. Yet the nerves rectify the image to its “right or natural Posture.”

Six muscles provide fast and accurate rotation of the eye “to move it upward, downward, to the Right and Left, obliquely and round about,” to direct one’s field of view without requiring head motion. These and other features led Ray to conclude that the eye was designed, for it was “highly absurd and unreasonable to affirm, either that it was not Design’d at all for this Use, or that it is imposible for Man to know whether it was or not.”

Far More Detailed Knowledge

Of course, today our knowledge of the eye’s design is far more detailed. Particularly striking are the incredible mechanisms at the molecular level. There is the vision cascade within the rod and cone photoreceptor cells giving us extremely sensitive vision. And there are the analog optical mechanisms operating on the incoming light, and the digital electro-chemical mechanisms post-processing the electrical signals produced by the photoreceptor cells.

Is not all this powerful evidence of design? Not according to Lents. Yes, Lents agrees that the human eye is indeed a marvel. But along with all the complexity, there is a long list of faults. There is, for example, myopia, or near-sightedness familiar to so many people. The problem is that myopic eyes are too long so that the image comes into focus before reaching the retina at the back of the eye. Of course, the opposite problem, far-sightedness, is also familiar.

While near-sightedness and far-sightedness may pose inconvenient vision problems, Lents has only begun. Next there are the serious problems of glaucoma, cataracts, and retinal detachment. And if that was not enough, all of us face a future of weakening and even loss of our vision over our lifetime. Add to all this the problem of color-blindness (affecting hundreds of millions of people worldwide) and Lents has made his point: there are substantial problems with human vision which refute design. “Why,” asks Lents, “an intelligent designer would deny his favorite creatures the excellent vision that he provided lowly birds is quite a mystery.”

In fact, Lents’ argument goes further than abstract evidence. He has personal experience with this biological shortcoming as his vision is, by his own admission, “terrible.” “In pre-history,” Lents reports, “I would have been worthless as a hunter. Or a gatherer, for that matter.”

Two Problems

But herein lies the first of two problems. For Lents’s “junk design” argument is too good. He correctly points out very significant problems with what is probably the most important human sense; at least insofar as evolution is concerned. Vision is crucial in evolution’s calculus of reproductive fitness. Even Lents admits his own vision would have rendered him an evolutionary loser. Such problems, as Lents eagerly points out, are both significant and common. Lents thinks he has refuted design, but in fact this terrible human vision system never would have survived evolution’s ruthless natural selection filter. Its very existence refutes evolution.

Lents has made a powerful argument against evolution rather than intelligent design, for evolutionary theory predicts no such failure would survive evolutionary history. This certainly is a strange way to formulate an argument against intelligent design. How is it that Lents concludes evidence that contradicts evolutionary theory refutes design?

We have already seen, above, the answer to this question. It lies in Lents’s view of what an intelligent designer would and would not do. Lents concludes this “bad design” evidence refutes design because he believes an intelligent designer would not allow for a vision system that has the problems Lents describes.

Simply put, Lents’s argument entails an assumption about the designer. This brings us to the second problem with his argument — it is not based on empirical science, but rather on metaphysics. There is no scientific experiment one could perform to test Lents’s claim because it is not scientific in the first place. Instead, it is based on theological utilitarianism, a metaphysical position on which ID is agnostic, but evolution requires.¹

Nathan Lents finds many faults with the human eye. He therefore insists that the human eye is a powerful refutation of design. What Lents does not understand is that he is not arguing against design; rather, he is making a theological argument, and in the process, he has refuted evolution.

Notes

1. Hunter, Cornelius. 2021. The Role of Non-Adaptive Design Doctrine in Evolutionary Thought. Religions 12:282. https://doi.org/ 10.3390/rel12040282.