Readers may remember Nathan Lents, author of Human Errors: A Panorama of Our Glitches, from Pointless Bones to Broken Genes. In 2015, he was holding forth about the poor design of the human eye: “The human eye is a well-tread example of how evolution can produce a clunky design even when the result is a well-performing anatomical product.”
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.Cornelius Hunter, “Did Nathan Lents Refute Design?” at Evolution News (January 21, 2022)
Well, if we want to get theological about it, Moses was a man slow of speech. Why didn’t the Lord, who had chosen him to free the people, make him eloquent? (Or cure his speech impediment, if that’s what it was.) All we know is, he did free the people anyway. The trouble is, as Hunter notes above, trying to figure out what God should or should not do, apart from the record, is not science.
From the science record, the human eye is very well adapted to what it needs to do.
Incidentally, Lents believes that he would have failed as a (Palaeolithic?) hunter, due to poor eyesight and therefore the eye is poorly designed. There’s another way of looking at it: Problems like that spurred the development of agriculture. Agriculture does not need everyone to have the strength and skills of a hunter. Plenty of people can plant and harvest grain and grind it in a mill. Overall, the human race is probably better off with a mix of strengths and weaknesses, for creativity and innovation.