The Atheist's Guide to Reality_ Enjoying Life Without Illusions - Alex Rosenberg [29]
“Mother Nature” is just the disguise natural selection “wears” (there’s that volitional metaphor again) when its results look particularly nurturing to us. In the rest of this book, hold me to the promise that any talk about purposes is harmless metaphor. Intentions, volitions, designs, solutions, or any other kinds of actions in nature—implied or expressed—must always be cashed in for the mindless process Darwin discovered.
Natural selection explains the blade of grass in just the way Kant thought was impossible. It explains the emergence and persistence of the most intricate adaptation by a prior sequence of lesser and lesser adaptations. In turn, that sequence can be traced back to a starting point with zero adaptation. The most complex and impressive adaptations are the result of a chain of events that starts with no adaptations at all, just molecules in random motion. That leaves nothing for purposes, ends, goals, to do anywhere in nature. Darwin figured out the only process for producing adaptation that is allowed by the laws Lord Kelvin discovered. It’s ironic that despite Kelvin’s attack on Darwin, his great contribution to physics—the second law—makes natural selection inevitable.
To review a bit from the previous chapter, the second law of thermodynamics tells us that with very high probability, entropy, the disorder of things, increases over time. The second law’s consequences are almost as familiar to us as any physical process. Hold a cup while someone pours coffee into it, and you feel the cup getting warmer. Meanwhile, as it is poured into the cup, the coffee gets cooler. Pour some cream in the cup of coffee and watch it spread out on the top. Add a sugar cube. It dissolves. All these effects—the cooling of the coffee, the heating of the cup, the spread of cream, and the sugar’s dissolving—demonstrate the second law’s requirement that disorder increases almost everywhere almost all the time.
The second law is, of course, not restricted to milk protein molecules in coffee cups. It has the sobering implication that, just like in the coffee cup, eventually everything is going to even out everywhere.
But the biological realm seems to show the opposite of second-law disorder. It reflects persistent orderliness: start out with some mud and seeds, end up with a garden of beautiful flowers. The ever-increasing adaptation of plants’ and animals’ traits to local environments looks like the long-term increase in order and decrease in entropy. So we have to square the emergence and persistence of adaptation with the second law’s requirement that entropy increases.
You may be thinking that if adaptation is orderly and increases in it are decreases in entropy, then evolution must be impossible. Some creationists have actually argued this way. This line of reasoning makes a slight mistake about entropy and magnifies it into a major mistake about evolution. The second law requires that evolution produce a net increase in entropy. Increases in order or its persistence are permitted. But they must be paid for by more increases in disorder elsewhere. Any process of emergence, persistence, or enhancement of adaptation must be accompanied by increases in disorder that are almost always greater than the increases in order. The “almost” is added because, as we have seen, increases in entropy are just very, very probable, not absolutely invariable. It won’t be difficult to show that Darwin’s explanation of adaptation, and only Darwin’s explanation, can do this.
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