Intelligent design, continued

The reason I'm harping on the meaning of "randomness" is because of people who don't know better (or worse – who do) saying things like this:

Read these books, then tell me you are still a committed believer that the Universe is full of nothing but matter and that random chance with no designer is responsible.

If by "random chance" you mean that nothing is predictable, I doubt you'll find any scientists who believes that. Anyone who argues against that proposition is arguing against a straw-man. Ultimately, this sort of argument is a waste of time for both the arguer and anyone listening.

One of the features about Darwin's theory that is widely misunderstood is that it combines two ideas. The first idea is the notion of random variation. This is not terribly novel – we see it all the time. Children look a lot like their parents, but not exactly like them, and no two are alike. (Even identical twins have differences.)

The other principle in Darwin's theory is that of natural selection.

As a pigeon fancier and breeder, Darwin had lots of experience with artificial selection. He'd seen the incredible variety of pigeons breeders were able to get in a relative handful of generations, starting with the basic pigeon stock. It occurred to him that nature could select for features too.

Any feature that any organism possessed that had any impact on how well it survived and reproduced could be subject to selection. For example, an animal with longer fur might be better suited to a cold climate, and would be more likely to survive long enough to reproduce. Of course, if this animal happened to be born in a very warm climate, it would overheat very easily, and thus be less likely to survive and reproduce.

Any number of features have plausible, and in many cases easily measured, effects on both survival and reproduction. Many other features turn out to have effects that become apparent only after some study. The point is, any and all variations in any and all features that have any impact on survival are subject to natural selection. The winners of the natural selection game win the same thing the winners in artificial selection do – the right to breed and pass along their genes to the next generation.

Here's the punch line: the feedstock for evolution – random variation – is random. But natural selection is selection – the very opposite of random.

Living organisms undergo small changes during reproduction, and each change causes the organism to explore some nearby piece of probability space. If it fails to survive and reproduce in that piece of probability space, it is removed from the system by natural selection and the exploration stops at that point. Some future explorer may wander through, but it will meet the same fate at the hands of natural selection.

Other organisms may find themselves in parts of probability space that are friendlier. There, they may thrive and reproduce, and their offspring will exhibit slight variations from theirparents. Some of these variations will reverse the latest change – they'll be "explorations" back along the path followed by the last generation. Others will be explorations in other directions.

If this sound slow, it is. But when you have trillions of living things, each making their own little explorations every generation, you can cover a lot of ground. the SETI at home project uses thousands of home computers to grind through Saganloads of data, carrying out computations that would bankrupt even a very well funded project. But with thousands of computers donating "extra" processing time, a whole lot of calculation gets done in a very short time. Right now, they're managing some 64.75 trillion floating-point operations per second. A two-gigahertz processor manages two billion computing cycles every second, and a floating point operation will take at least a few cycles. The distributed computing power behind SETI at home amounts to probably a couple hundred thousand desktop computers worth of calculating power.

Now consider a planet full of miniature computers, each exploring a small corner of the possibilities available to living things, and you see a lot of things can happen in a million years.

Yes, there are some fascinating, beautiful, and intricate designs in nature. But they were designed by natural forces, and driven by one of the most powerful forces in the universe – the urge to reproduce.