Intelligent design of the human eye is often cited by religious zealots as the single most convincing argument for Intelligent design/a creator. I believe the eye has evolved like all other living items on earth. But I lack conviction in my debate. Any advice appreciated. Thanks.
Posted: December 3rd 2008
Dave Hitt www
Ask the zealot if they had a choice between being totally blind and being able to see things out of focus, which they’d pick. They’ll have to admit that out of focus vision is better than no vision at all. Then ask if they’d rather have vision that was out of focus and devoid of color, or be totally blind. Again, the choice is obvious. How about if they could only see vague shapes around them? Once again, it would be better than being blind. And finally, if the only thing they could detect was if they were in the light or the dark, would that be better than blindness?
Once they’ve admitted that any sight, no matter how limited, has great advantages over being completely blind, they’ve admitted that eyes at any stage of development are useful.
Then point out that we are surrounded by examples of eyes at all stages of development, from the highly developed (but still flawed) human eye to simple light sensitive cells on some creatures, and everything in between. If they were created, why would God limit some creatures to poor sight and give good sight to others?
Posted: December 7th 2008
bitbutter www
If biological systems having the appearance of design qualify as evidence for the existence of a designer, ask the ID-er what they think it means that those biological systems have what look like serious, life-threatening, design faults–faults that human engineers can identify and imagine fixes for. Does this mean that the intelligent designer made sub optimal designs, designs that humans could improve? If the ID proponent wants to resist this conclusion, what grounds can he give for doing so?
Of course this is just sport. It’s easy to show the ID-er how the eye is not irreducibly complex, and you should do so. The committed ID-er can probably find other examples of biological systems that scientists have yet to understand the evolutionary history of. But this is an exercise in finding the Designer Of The Gaps. We ought not to be impressed with any argument for a designer that relies on the current, incomplete, state of our understanding. If necessary remind your interlocutor that theists once argued for the existence of an immaterial superpower using the weather and disease, citing them as aspects of the world that are unexplainable without appealing to the behaviour of such an invisible being. Appeals to ignorance have a short shelf life.
Point out the other error these people are making, the fallacy of the false dichotomy. If 'blind purposeless evolution’ did ever turn out to be false, that doesn’t mean that it would be true that there’s an intelligent designer. Ask them for positive evidence for Intelligent Design: What testable predictions does ID 'theory’ make? What studies have been carried out to test these predictions?
I was sent a link to a useful interactive presentation which may be interesting for those who want to learn more about the anatomy of the human eye.
Posted: December 4th 2008
logicel
You could rip off Arlo Guthrie’s song, Alice’s Restaurant, and simply sing, You can get anything you want by climbing Mount Improbable, and walk away.
Excerpted from p.124, The God Delusion:
And, as with wings and flight surfaces, plausible intermediates are not only easy to imagine: they are abundant all around the animal kingdom. A flatworm has an eye that, by any sensible measure, is less than half a human eye. Nautilus (and perhaps its extinct ammonite cousins who dominated Paleozoic and Mesozoic seas) has an eye that is intermediate in quality between flatworm and human. Unlike the flatworm eye, which can detect light and shade but see no image, The Nautilus 'pinhole camera’ eye makes a real image; but it is a blurred and dim image compared to ours. It would be spurious precision to put numbers on the improvement, but nobody could sanely deny that these invertebrate eyes, and many others, are all better than no eye at all, and all lie on a continuous and shallow slope up Mount Improbable, with our eyes near a peak – not the highest peak but a high one.
IDiots allege that specialist biological literature has ignored the problem of irreducible complexity, of which the eye is just an example.
From p. 131, TGD:
The falsehood of this allegation was massively and (to Behe) embarrassingly documented in the court of Judge John E. Jones in Pennsylvania in 2005, where Behe was testifying as an expert witness on behalf of a group of creationists who had tried to impose 'intelligent design’ creationism on the science curriculum of a local public school – a move of 'breathtaking inanity’, to quote Judge Jones (phrase and man surely destined for lasting fame).
And if the IDiots did ever manage to come up with an authentic case of irreducible complexity, they will dismantle intelligent design theory along with evolution. From p. 125 of TGD:
...as I keep saying and will say again, however little we know about God, the one thing we can be sure of is that he would have to be very very complex and presumably irreducibly so!
Another handle on this problem, and much closer to home than flatworms, is provided by this quote from p. 123
A cataract patient with the lens of her eye surgically removed can’t see clear images without glasses, but can see enough not to bump into a tree or fall over a cliff.
Posted: December 4th 2008
SmartLX www
For starters, it helps to have some idea of the steps a creature might go through to develop a simple light-sensitive patch of skin into an eye. This short video from an old documentary by Richard Dawkins is very easy to understand, and still current.
Next, in Wikipedia’s article on the subject you’ll find examples of animals whose eyes hasn’t evolved to quite the same standard as ours. They’re just pinhole cameras on the nautilus, or simply a light-sensitive pit on a planarium. The links at the bottom contain more examples.
Finally, the irreducible complexity argument related to the eye relies on the idea that if it lost any component or were slightly simpler, it would be useless. Here’s Richard Dawkins again during Growing Up in the Universe, adding components to a model eye one by one (fast forward a bit if you like, and then go to Part 2), and getting plenty of use out of it long before it’s finished.
Posted: December 3rd 2008