Earth and Evolution: No Purpose, No Design
Evolution happens because it can. Period.
BY: Dr. Daniel Dennett
Several months ago, I sat down with author Robert Wright to discuss-among other things--evolution and whether it shows signs of purpose or direction. As anyone can see from thevideoclip on Wright's website
, Wright has a vision--which I don't share--that led him to push me hard to agree with him about purpose in evolution. It never occurred to me that I was conceding a version of his point, and I don't accept the interpretation he still wants to put on my acquiescence, after a series of email exchanges. This was a case of miscommunication: he overinterpreted me, and was unwise to publish his strained version of what I had said without checking with me.
Here, for the record, is what I continue to think about the existence of purpose in the universe:
If we view the universe as a whole from the widest possible viewpoint-over all time since the Big Bang, say-there is no purpose of any sort. Evolution happens because it can happen. Period.But
evolution being what it is, it spawns what I call "cranes"-local, evolved "lifting devices" that increase the local power of the evolutionary algorithms. (John Maynard Smith called these cranes the "major transitions of evolution" and discusses them in another of Wright's videoclips.) There are cranes that spawn cranes that spawn cranes. , and hencesub-processes
within the vast unrolling of evolutiondo
take on first what we might call quasi-purpose (or even pseudo-purpose-I don't care what term you use to diminish this phenomenon and distinguish it from the notion of human purposes: conscious, foresighted purposes). These in turn eventually bloom into processes that exhibit our kind of purposes. But even these processes are composed, down in the cellular basement, of processes that don't have such fancy purposes-those robotic cells are purposeful but clueless about why they do what they do.
So now: ontogeny (the process of embryonic development) has a middle-spectrum sort of purposiveness; it is itself a product of natural selection, optimized over the eons, so we can indeed attribute to it plenty of design. But of course it lacks foresight, and doesn't represent its goals, etc. What about the growth of life on Earth? No. It shows no signs of having been optimized by a process of natural selection. It is a bottom-of-the-design-barrel process. It happens because it can happen. Period.
Unlike ontogeny, which does exhibit "directional movement toward functionalityby design
," the growth of life on Earth exhibits movement toward functionality without design. To the extent that it exhibited movement toward functionality by design, itwould
be evidence of purpose--but only of the attenuated sort of purpose exhibited by ontogenesis. That is what I thought I agreed to when I answered Wright's question. Check the videoclip and see for yourself.