Sunday, March 12, 2017

From Bacteria to Bach and Back


nybooks |  As for the underlying mechanisms, we now have a general idea of how they might work because of another strange inversion of reasoning, due to Alan Turing, the creator of the computer, who saw how a mindless machine could do arithmetic perfectly without knowing what it was doing. This can be applied to all kinds of calculation and procedural control, in natural as well as in artificial systems, so that their competence does not depend on comprehension. Dennett’s claim is that when we put these two insights together, we see that
all the brilliance and comprehension in the world arises ultimately out of uncomprehending competences compounded over time into ever more competent—and hence comprehending—systems. This is indeed a strange inversion, overthrowing the pre-Darwinian mind-first vision of Creation with a mind-last vision of the eventual evolution of us, intelligent designers at long last.
And he adds:
Turing himself is one of the twigs on the Tree of Life, and his artifacts, concrete and abstract, are indirectly products of the blind Darwinian processes in the same way spider webs and beaver dams are….
An essential, culminating stage of this process is cultural evolution, much of which, Dennett believes, is as uncomprehending as biological evolution. He quotes Peter Godfrey-Smith’s definition, from which it is clear that the concept of evolution can apply more widely:
Evolution by natural selection is change in a population due to (i) variation in the characteristics of members of the population, (ii) which causes different rates of reproduction, and (iii) which is heritable.
In the biological case, variation is caused by mutations in DNA, and it is heritable through reproduction, sexual or otherwise. But the same pattern applies to variation in behavior that is not genetically caused, and that is heritable only in the sense that other members of the population can copy it, whether it be a game, a word, a superstition, or a mode of dress.
This is the territory of what Richard Dawkins memorably christened “memes,” and Dennett shows that the concept is genuinely useful in describing the formation and evolution of culture. He defines “memes” thus:
They are a kind of way of behaving (roughly) that can be copied, transmitted, remembered, taught, shunned, denounced, brandished, ridiculed, parodied, censored, hallowed.
They include such things as the meme for wearing your baseball cap backward or for building an arch of a certain shape; but the best examples of memes are words. A word, like a virus, needs a host to reproduce, and it will survive only if it is eventually transmitted to other hosts, people who learn it by imitation:
Like a virus, it is designed (by evolution, mainly) to provoke and enhance its own replication, and every token it generates is one of its offspring. The set of tokens descended from an ancestor token form a type, which is thus like a species.