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Darwin's Dangerous Idea

Evolution and the Meanings of Life 
Daniel C. Dennett

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I think he is generally right as far as he goes. In some ways the most important contribution was to clearly articulate that evolution is an algorithm. An algorithm that can run on various substrates (genes, brains or computers) and can generate good design from randomness or guesswork.

One area where he seems not-quite-right is in his criticism of Gould. It seems that Gould has frequently said things that others have interpreted as refuting evolution in some way, or the objectionable aspects of the neo-Darwinian synthesis, and he has frequently said that this or that thing was not “Darwinian”. And I myself had thought he seemed a bit incoherent and desperate in his defense of religion as having a “non-overlapping magisterium” with science, and at times when talking about his beliefs that the emergence of intelligent life was very non-inevitable and in fact extremely improbable, that there was some sort of “whistling in the dark” defiant edge to this.

But I think that there is definitely something to the “just so story” criticism, and also to the sense of the claims in “Wonderful Life” about contigency, and also there is perhaps something to the idea of a “spandrel”. But the difficulty of coming up with clearly invalid just-so-stories and spandrels without resorting to clear straw-man fabrication does show these concepts are difficult to apply in practice.

w.r.t. “Wonderful Life”, Dennet's point about Gould's two pictures of the tree of life, the cone of increasing diversity and the flat bush with scraggly risers, that the two are topologically equivalent is perhaps not true, and in any case misses Gould's main point, which is that the two picture demonstrate right and wrong ways of thinking about what happened, and not so much different versions of the facts.

Gould is strongly resisting the agenda of substituting evolution as a substitution for divine creation in giving us a sense of purpose, meaning, or comfort. In particular, the idea of the “great chain of being” as interpreted under evolution, where God set the rules so that we ethical and rational creatures inevitable arose, and then gave the world a spin. The lack of any direction toward humanity in evolution is clear and uncontroversial among the evolutionarily literate, but a weak form seems to persist in the idea that life diffuses out in all directions in design space, and would inevitably explore the conscious life region. This is the cone-of-increasing-diversity picture. But as Dennet points out, design space is Vast, and I add that there has been only so much time to explore it.

Clearly Gould believes that intelligent life was very unlikely, and Dennet seems to think it was rather more probable. Of course, retrospective bias tends to add an air of inevitability to whatever happened, and in this regard there is general cause to be suspicious of Dennet's view. Dennet correctly argues that Gould has not really proven his view, but the arbitrary and capricious nature of the extinctions after the Cambrian explosion clearly do undermine any comfortable view of the nicey-nicey progression toward observers capable of retrospective bias. It also seems that in his zeal, Dennet goes too far in downplaying the special uniqueness of the Cambrian explosion in evolution.

So was Gould really looking for a “skyhook”, and was his ambivalence being correctly read from his writings, without noticing the facts that Gould proposes? I do think that Gould, and I, and probably many who really believe what Science tells us, are troubled by the emptiness of the resulting universe, and like Gould, we perhaps become a bit brittle in our attempt to put on a brave face.

Another take on just-so-stories is that the “rightness” of a story depends on the consistency of the story with the other stories our culture tells us, its mythic power and summary of the human condition. Fairy tales are all about how kindness to the stranger without any expectation of reciprocity is paid back many-fold, about how virtue and industry are rewarded, and how laziness and selfishness contain the seeds of their own destruction. Disney movies are not so different. Stories where the reverse is true are not considered suitable for children, and if the perverse stories lack a dark tone and sense of injustice, then you wonder about adults who like to tell or listen to those stories.

Our cultural stories are to some degree true in our cultural context (though we do have to be wary of deceptive encouragement of self-sacrifice for social ends.) But the story of life-before-philosophers lacks this context and those morals. The story that Gould reads in the Cambrian explosion is that, as well as being endlessly creative, nature is wasteful, uncaring, arbitrary and capricious. Mass extinctions in particular offend our sense that virtue and industry should be rewarded, because organisms that were beautiful and successful are struck down, and other organisms that were marginal in normal times survive, perhaps due to just having a previously unimportant trick like tolerance for low oxygen levels, or perhaps simply due to being located out of the way of harm. We can't even tell who the good guys and bad guys are, and fall back to rooting for the home team (the chordates.) Even this last is mistaken, because only by retrospective bias do we know a path that has the “right” outcome (ourselves.)

Once we cast off the burden of evidence and spin stories based primarily on their beauty, then it's not surprising that we end up proving that things naturally end up the way that we see them (though the lens of our culture.) The rightness and beauty of a story is only a poor guide to its truth, but often it's all we've got.

Another interesting area where Dennet is gnawing on the same carcass (if not the same bone) as I am is in ethics. He has a very funny suggestion is that what we need is not a grand theory of ethics, but a “Moral first aid manual” tell us what to do while we're waiting for the doctors of philosophy to arrive to debate the matter. What he's talking about is the importance of cognitive limitations to practical ethics. Useful ethics must be “computable”, which the consider-all-thing approach is not even in principle. And he makes the interesting point that: It suggests that what Bernard Williams calls the ideal of “transparency” of a society – “the working of its ethical institutions should not depend on the members of the community misunderstanding how they work” – is an ideal that may be politically inaccessible to us. In other words, the working of our society could well depend on self-deception or unconscious conformance. Our story of why we do something (perhaps in terms of enlightened self-interest) could be at odds with the actual value of the behavior to society. Cultures where people think that way have been more successful, so we tend to think that way. This self-deception is a clever hack to work around our selfish instincts.

Though his discussion of language was not greatly interesting because I assume language did evolve, the analogy between “language instinct” and “social instinct” is interesting (and perhaps there is actual parallel structure of these interdependent facilities.) Clearly we have some hardwired modules for phonetic generation and perception and grammatic manipulation, and there are critical periods for training these. The operation is completely automatic and unconscious. Within the scope of these capabilities, a wide variety of languages are possible, and are culturally constructed. Similarly, there are likely modules for important social functions like imitation, prestige bias, conformance bias, cheater detection, socially productive behavior, storytelling and story evaluation. These modules communicate with our conscious mind mainly via emotions, as do other “selfish” motivations such as self-preservation and reproduction. Within this structure, a wide range of cultural beliefs and meta-beliefs are possible. For example, while there is something fundamental and important about selfishness, the fact that our culture has a relatively positive view of selfishness in comparison to many traditional cultures leads some to argue that selfishness is so natural that anyone who says they are being unselfish is deluded. The riff I'm working on here is that, yes there is self-deception going on, but those who theorize that only selfishness is real and altruism is deception have it precisely wrong. Often we think we are acting in our self-interest, but actually we are pursuing culturally advocated values that are more valuable to the culture than to the individual, and it is highly valuable to society that this deception remain in place. Also, living in a successful polity may be so valuable to our genes that this deception has become instinctive. The poor ego is stuck between a rock and a hard place, and doesn't know who to believe or what to do. Both the Id and the Superego are lying to it.

books/darwins_dangerous_idea.txt · Last modified: 2010/05/16 17:23 by ram