Dennett, evolution, and "higher purpose"
Did Daniel Dennett admit that there is a "higher purpose" to life? asks Robin Varghese of 3quarksdaily. This strikes me as an odd way of putting the question. The alleged "admission" is to be found in an interview between Robert Wright and Daniel Dennett.
You can watch the Wright/Dennett Interview in its entirety. Then decide whether Wright's synposis is fair:
I have some bad news for Dennett's many atheist devotees. He recently declared that life on earth shows signs of having a higher purpose. Worse still, he did it on videotape, during an interview for my website meaningoflife.tv. (You can watch the relevant clip here, though I recommend reading a bit further first so you'll have enough background to follow the logic.) [Editor's Note: Since this article was published, Dennett has claimed that it misrepresents his views. Robert Wright responds to Dennett here.]
I submit Wright is being incredibly disingenuous in his synopsis of the interview and, I might add, in his Editorial Note. The video doesn't misrepresent Dennett's views. Dennett didn't object to the interview, he objected to Wright's post hoc editorializing. Dennett wrote:
"This is ridiculous: Wright misinterprets his own videoclip (I am grateful that it is available uncut on his website, so that everybody can see for themselves).
[Via Daily Dish. Yes, you read right.]
Dennett believes that natural selection explains the purposes we see in living things. By "purpose" Dennett means something closer to Aristotelian teleology than theology. Dennett believes that eyes are quite literally for seeing, that wings are for flying, that gills are for breathing, and so on. In the pre-Darwinian era, these commonplace observations were treated as an open-and-shut case for intelligent design. Living things do seem different from, say, geological formations. A cave system can be incredibly complex, but it doesn't seem like the various bits and pieces are for anything. It's easy to imagine how this intricate object could simply reflect a bunch of stuff that happened.
Dennett argues that Darwin made atheism intellectually respectable because the theory of natural selection explains how a non-conscious process could generate complex, designed organisms.
Wright is making a rather strange argument: If the evolution of life on earth were like the embryological development of individuals, wouldn't that be evidence of Intelligent Design? Wright's key points seem to be i) evolution is directional; ii) embryological development is directional. He claims that in both cases we see developing complexity and integration of function. Wright asserts that life on earth can be seen as a directional process of organism development in which human beings assume the function of the planetary nervous system:
Meanwhile, as the human species is becoming a global brain, gradually assuming conscious control of the planet's stewardship, other species—also descended from that single primitive cell that lived billions of years ago—perform other planetary functions. Trees are lungs, for example, generating oxygen.
Dennett offers a qualified assent to (i). He agrees that there has been a trend, though by no means an inevitable or irreversible trend, towards evolutionary complexity. Dennett has several reservations about (ii). As you can see in the video, he objects that embryological development doesn't necessarily progress towards ever-greater complexity.
Wright seems to arguing from unarticulated premises, which I will attempt to spell out. We agree natural selection designs organisms by differential reproduction of self-regulators. Natural selection helps explain the transition from single cell to complex organism, both at the level of the type and the level of the individual.
Suppose that the Earth is one big organism. Wright implies that natural selection couldn't explain Organism Earth--which seems right because the earth itself doesn't have the properties necessary to participate in natural selection. It's not a self-replicator, it doesn't have heritable components that contribute differentially to the survival of its offspring, etc. So, maybe we need ID to explain Organism Earth, even if blind natural selection explains the design inherent in individual earth species.
As I think Dennett argues in the video, this argument assumes that Organism Earth shows evidence of purpose in the same sense as wings and eyes. This is a dubious assertion. There's no particular reason to believe that the earth is relevantly analogous to an organism. The features of earth aren't obviously "for" things in the same sense as bodily structures. Moreover, there's no reason to think that the earth was more "suited to" or "designed for" life on earth as we know it, as opposed to other possibilities: no life at all, a "saw tooth" pattern of rising and falling average complexity, etc. Wright seems to be implying that earth must have been created with the purpose of fostering life, but he doesn't supply any motivation for his view.
When pressed, Dennett agrees that if the history of life on earth were relevantly like embryological development, then that might constitute evidence of ID. Note that by "evidence" Dennett doesn't mean proof or presumptive proof. Wright asks whether, if such similarities could be substantiated empirically, whether this might count in favor of some version of ID. He's not asking whether this would be a knock down argument for ID, or even whether ID would be the best explanation for these similarities. Wright is simply asking whether an ID-proponent could find these discoveries encouraging (were anyone to make them.) Big deal.
I just lost a lot of respect for Robert Wright. He took an interesting exchange of ideas, published a grandstanding gloss, and issued a graceless response when challenged.
[In the interest of full disclosure I should add that Dennett is my mentor, friend, and former professor.]
[Edit: Tim Sandefur has an excellent analysis of the Dennett/Wright flap. Hat tip to Ed Brayton of Dispatches from the Culture Wars. Also, here's another good post from Dan of Doing Things With Words.]