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A Bit Confused

Skeptical Inquirer, March, 2001 by David Roche

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Shannon information and complexity are quite distinct concepts. As we have already seen, various systems can be interpreted as having lots of one without much of the other. A common mistake of those attempting to use information theory to debunk Darwinian evolution is to confuse the two concepts. Dembski's "complex specified information" is the most prominent example (Dembski 1998).

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Once we understand the difference between these two types of information--Shannon information and complexity--it is easy to see what's wrong with the information argument against evolution. If we interpret biological systems in information terms, we can see that natural selection does tend to decrease the amount of information, but only Shannon information. Natural selection simply removes some members from a population, making it more homogenous and less diverse. The resulting population is easier to describe in detail and so has less Shannon information. Conversely, mutation makes the population less homogenous and so increases the amount of Shannon information.

Looking at the amount of complexity in the biological system, however, the situation is somewhat different. Mutation is a random process, and random processes do not, at least on their own, generate complexity. Natural selection, however, is nor a random process. It is an ordering process, creating structure from noise and increasing the degree of regularity in the biological system. Since complexity is simply the length of a concise description of all the regularities in such a system, natural selection, in conjunction with random mutation, can tend to increase complexity.

Whichever way we interpret the evolutionary critic, explaining the origin of biological information is straightforward. If by "information" the evolutionary critic means Shannon information, then there is very little to explain. The second law of thermodynamics will suffice. The world tends toward disorder, and this disorder is a physical embodiment of Shannon information. On the other hand, if we interpret "information" to mean complexity, then we are simply left with answering the familiar question of how the Darwinian process could give rise to such complex organs as the vertebrate eye; a question already thoroughly dealt with by many biologists (e.g., Dawkins 1986).

The great achievement of Darwinism is not that it explains the origins of information (in the Shannon sense), but that it explains the origins of complexity. And it does so in terms of a completely material process: random mutation followed by non-random selection. Via such a process, the simple can give rise to the complex; "from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved" (Darwin 1859).

David Roche is in the Unit for the History and Philosophy of Science, University of Sydney, Australia. E-mail: droche@unsw.edu.au.

Note

(1.) After writing this statement, I decided to test it empirically. I created three text files: one containing 100,000 As, another containing 100,000 pseudorandom letters, and a third containing Shakespeare's The Tempest. I then ran each through the compression program WinZip, and achieved compression ratios of 99.3%, 2.5% and 58.4% respectively.

A Bit Confused

Skeptical Inquirer, March, 2001 by David Roche

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