The Greatest Show on Earth

The Greatest Show on Earth – What about bad design?

In chapter 11 of The Greatest Show on Earth, Richard Dawkins alludes to a number of systems which he regards to be badly or ‘unintelligently’ designed. The point he makes is a rather elementary logical fallacy -- design does not have to be perfect; it just has to be good enough. The fact remains that living systems exhibit clear marks of the action of an intelligent agent, even if the design is somewhat less than perfect. As an analogy, consider Microsoft office software. Microsoft office applications often possess certain imperfections, but no-body would infer that the programming script was the product of undirected mechanisms. Ultimately, Richard Dawkins is here depending upon the utilisation of theological arguments in order to support his case. The theory of intelligent design states that certain features of the natural world exhibit indicators of intelligent design. Questions relating to the identity or skill of the designer are questions for theologians and philosophers to address, and thus stand independently from biological or scientific concerns.

The Greatest Show on Earth - The Test
Nonetheless, let us take one of Richard Dawkins’ examples of bad design, as presented in The Greatest Show on Earth, subject it to scrutiny and see how it holds up. If it can be demonstrated that there exists functional reasons for the relevant instances of apparent ‘bad design’ or if new evidence suggests a pattern of degenerative evolution (that is to say, evidence of decay of an otherwise rational and beneficial original design), then the argument would no longer hold water.

On page 353-355 of The Greatest Show on Earth, Richard Dawkins alludes to the often-cited example of the inversion of the vertebrate eye retina as an instance of ‘bad design’. However, recently identified functional reasons for this design challenge the old Darwinian claim. Biologist George Ayoub has shown, for example, that the vertebrate retina provides an excellent example of what engineers call a constrained optimisation, in which several competing design objectives are elegantly balanced to achieve an optimal overall design.

Light at various wavelengths is capable of inducing degenerative effects on biological machinery. The retina is clearly designed with the inbuilt purpose of withstanding the toxic and heating effects of light. The eye is well equipped to protect the retina against radiation from the outside world. Besides the almost complete exclusion of ultraviolate radiation by the cornea and the lens together, the retina also serves a crucial role in protection against such damage -- for example, producing substances with combat the damaging chemical by-products of light radiation.

The photoreceptors, therefore, need to be in direct contact with the retinal pigment epithelium, which plays an essential part in sustaining them. The retinal pigment epithelium, in turn, requires to be in direct contact with the choroids. Both of these are required in order to satisfy the nutritional requirements and thus prevent overheating the retina from focused light (as a consequence of the heat sink effect of bloodflow).

If, conversely, the human retina were ‘wired’ the other way as Dawkins proposes that it should be, these two opaque layers would need to be interposed in the path of light to the photoreceptors, which really would be bad design!

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