Does evolution have a purpose? (Evolution)

by dhw, Sunday, October 12, 2014, 11:58 (3477 days ago) @ David Turell

dhw: All of these wonders, including the human body and brain, “exceed all requirements of nature”, since nature “requires” nothing beyond bacteria. Perhaps the power of invention has led to this vast variety, and we are a kind of culmination.
DAVID: Exactly the type of point I am raising. We really don't know what drives evolution. Darwin chose survival, but his group cannot define fitness. It could well not be survival but constant invention with the non-fit dropping along the wayside.
-We are in agreement.-dhw: I am suggesting that there is no overriding purpose, but that once set in motion, the inventive mechanisms within individual organisms or groups of organisms pursued their own “agendas”, thus giving rise to the great higgledy-piggledy bush of species that eventually led to our own.-DAVID: That is my free rein description. In this case humans are here by accident, and the odds against this result are enormous. This is Gould's 'series of contingencies' and we are the lucky accident of fate, the Glorious Accident of the book title. But accidents against enormous odds occur all the time the math folks tell us.
Against this thinking is the series of events leading to us. A universe that is fine-tuned for life, 20 major and 100 minor physical parameters, often exact to thousands of decimal places to allow a life-giving universe. The appearance of life from organic chemistry that arises from a totally inorganic chemistry universe.-The fine-tuning of the universe for life may be an argument against chance and in favour of a conscious creator, but it is not an argument against the “accidental” appearance of humans any more than it's an argument against the "accidental" appearance of myrmecophilous beetles or dinosaurs. Once the autonomous inventive mechanism (another argument against chance) set evolution in motion, all species would have created themselves out of earlier species, and in that respect humans, for all their special qualities, are no more and no less “accidental” than any other species.
 
dhw: There is no chance involved here, other than the randomness of environmental change.
DAVID: We can't prove environmental challenges drive evolution. They tend to remove the unfit, but why should new animals appear as complex advancements. The bacteria are still here, no more complex than in the beginning.-Agreed. We can't prove anything, including evolution. If we could, there would be no controversy. The inventive mechanism is a hypothesis, but it explains why new animals appear as complex advancements. These may well be linked to environmental challenges and/or opportunities.-dhw: Each branch of the bush is the result of deliberate design - not separately by a god but separately by succeeding generations of organisms whose inventive mechanisms adjust to or exploit environmental change. 
DAVID: Planning new organisms is a complex problem, coordinating new organs, as in the Cambrian. A posible inventive mechanism went wild then. How? That gap seem too great to expect the simple multicellular two-tissue layered Ediacarans to conjure up such a jump. I use the word conjure in its magical sense. Magic or purpose?-You are trotting out the same arguments that we have been over a thousand times. There is no magic involved. You were uncomfortable with your 3.7-billion-year, all-inclusive computer programme and with your God dabbling. I have proposed the alternative hypothesis of an autonomous, unpreprogrammed inventive mechanism, which you have accepted as a possibility (bearing in mind certain given constraints) and have even suggested must be within the genome. We don't know how it would work. It's a hypothesis. But if you believe in the continuum of evolution, you believe that existing organisms produced innovations leading to new species. A change in the environment during the Cambrian (e.g. an increase in oxygen levels) may have presented vast new opportunities for the inventive mechanism to branch out. See below on the subject of purpose.-dhw: You are right to say Darwin bet on chance, but only in the sense of random mutations. As far as the origin of life was concerned, he hedged his bets. If he had known what we now know about genetics, he might also have come up with the hypothesis of an inventive mechanism, and would no doubt have hedged his bets on the origin of that too.
DAVID: So, did the IM invent itself? Or again, no purpose? For me the evidence is strongly suggestive of purpose.-Your question is not a true alternative. The alternatives would be: did it invent itself, or was it invented by a designer (your God)? No purpose? That is the subject of this thread. If God invented it, you will have to read his mind, which you have previously attempted to do by insisting that his purpose was to create humans. Another possible purpose might be your God setting things in motion just to see what would happen (= divine experimentation/curiosity/relief of boredom). Or on a different level, both theistic and atheistic, there is purpose in the actions of all living things: a) to survive, and b) to see what they can make of their lives. (The inventive mechanism seeking improvement for the organisms it controls.) The latter is particularly attractive, as it mirrors the purpose that drives most humans in their daily strivings.