A Guide to Reality, Part 8

Chapter 3 of Alex Rosenberg’s The Atheist’s Guide to Reality is called “How Physics Fakes Design”, although Professor Rosenberg would be the first to object that physics isn’t the kind of thing that can fake anything. His point, of course, is that everything that looks like it’s been designed in the natural world (the human eye, for example) is merely the result of activity at the atomic and molecular level, which itself results from subatomic particles doing what they normally do.

In fact, Professor Rosenberg holds that things that really were designed (like your computer) are the result of the very same natural laws. Design, wherever it appears to occur, whether the result of evolution or conscious effort, is just another illusion. 

In this chapter, however, Rosenberg is focused on evolutionary adaptation:

If the physical facts fix all the facts, then the emergence and persistence of adaptations had better result from the laws of physics alone. In fact, they had better be the result of the operation of thermodynamics. Otherwise we will have to admit that there is more going on in the universe than physics tells us there is. Some physicists may be okay with this, but scientism has to reject it. We need to show that the process Darwin discovered starts with zero adaptations and builds them all as the result of the laws of physics alone. (51-52).

Rosenberg begins by offering a statement of the three essential features of the theory of natural selection, as stated by the biologist Richard Lewontin:

  1. There is always variation in the traits of organisms, genes, hives, groups or whatever it is that replicates or reproduces;
  2. The variant traits differ in fitness;
  3. The fitness differences among some of the traits are inherited.

As Rosenberg explains, the replication or reproduction that occurs in nature doesn’t always result in an exact copy being made (mutations occur, for example). He prefers calling this “blind variation” instead of “random variation” to emphasize the point that nature doesn’t cause these variations on purpose. Most such variations yield no benefit. Occasionally, one does. A “beneficial” variation is one that tends to be passed on to the next generation. Given enough time, such variations can result in complex structures like the eye. Evolution occurs.  

Getting back to physics, Rosenberg argues that the second law of thermodynamics (closed systems tend toward disorder) makes natural selection “inevitable” (although at the end of the chapter he says that the second law only makes it “possible”). He admits that the relationship between the second law and natural selection is puzzling, since natural selection seems to increase the amount of order or organization in the world. But he quickly disposes of this objection by pointing out that the second law only requires a “net increase” in disorder over time. Organization will occasionally increase, but almost always at the cost of more disorganization elsewhere (as when organisms grow by digesting food).

Next, in the space of 11 interesting pages, Rosenberg shows how molecular activity, all subject to the second law, results in what he calls “molecular evolution” (69). As he explains it, there is a lot of “thermodynamic noise” in the universe. Molecules are constantly copying themselves, sometimes imperfectly, and forming bonds with each other. These processes result in new molecular forms. Some molecules are more stable than others, meaning that they will tend to last longer in particular chemical environments. As environments change, however, certain molecules become less stable and break apart, while others come together, just as organisms adapt or fail to adapt to changes in their environments. These various processes satisfy the criteria for evolution described above:

Natural selection requires … reproduction, variation and inheritance. It doesn’t really care how any of these three things get done, just so long as each one goes on long enough to get some adaptations. Reproduction doesn’t have to be sexual or asexual or even easily recognized by us to be reproduction. Any kind of replication is enough (59).

The same goes for variation and inheritance. I would add that these processes must occur in an environment filled with enough matter and energy to keep things moving along. Then, through the course of countless such chemical interactions over immense periods of time, complex organic molecules can develop:

Thermodynamic noise constantly makes more and more different environments – different temperatures, different pH, different concentrations of chemicals, different amounts of water or oxygen or nitrogen, or more complicated acids and bases, magnetic fields and radiation. As a result, there will be a corresponding selection for more and more different molecules (69).

And here we are today, each of us a collection of atoms and molecules, each doing its individual thing:

And so on up the ladder of complexity and diversity that produces assemblies of molecules so big they become recognizable as genes, viruses, organelles, cells, tissues, organs, organisms … and us (69).

Not being a scientist myself, I can’t vouch for Rosenberg’s account of how all this works. However, it all sounds plausible to me. If you read the chapter, you will probably feel the same way.

One closing comment: people who don’t accept the fact that natural selection could eventually lead to a particular complex entity usually argue that such a thing couldn’t possibly happen. It’s inconceivable, they might say, that the human eye, which needs a bunch of parts that work together in order to work at all, could have resulted from a long series of evolutionary steps. It was Charles Darwin himself who offered the human eye as the biggest challenge to his theory. Rosenberg mentions this issue near the beginning of this chapter but doesn’t return to it. His goal in chapter 3 is to show how adaptation gets started, not how far it can go. I think, however, that it’s unwise to bet against science in its pursuit of explanations for mysterious things like the human eye or consciousness. Too many phenomena that used to be mysterious have already been explained.

In our next installment (assuming I stay sufficiently motivated): Good design isn’t just an illusion, it’s also rare, expensive and accidental.

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