Saturday, August 26, 2006


More Sources of Information

This is a sequel to my previous post on biological information.

Two things come to my mind when I think about information theory: communication theory (a la Shannon) and decision theory. Communication theory treats information as something to be transmitted as accurately as necessary; decision theory treats information as something that may make a difference.

Note that the decision-theory definition covers both human information and the sort of biological information that I talked about last time.

William Dembski, the apostle of "intelligent design", says "The fundamental intuition underlying information is not, as is sometimes thought, the transmission of signals across a communication channel, but rather, the actualization of one possibility to the exclusion of others." This is similar to my definition of information as "something that makes something happen". Notice, though, that information always seems to act with at least one remove: information molds the actor, rather than acting itself. With humans, the information changes the actors mental picture of the world, so the actor may act differently. In chemistry, hence (for our purposes) in biology, the information shapes the electric fields, so electrons act differently.

There has been lots of analysis of Dembski's concept of "complex specified information", so I won't belabor that. My quarrel is with his assumptions about information itself.

Dembski treats information as a free-floating concept: "For an example in the same spirit consider that there is no more information in two copies of Shakespeare's Hamlet than in a single copy. This is of course patently obvious, and any formal account of information had better agree." But in the real world this statement isn't always useful. If you have two copies of Hamlet, two people can read it at the same time, so decisions about staging and such can be made sooner. And it's by no means clear that an organism is indifferent to a second copy of a gene. The effects of Down syndrome are the result of a second copy of an entire chromosome.

Another result is the leaf-eating monkeys. Here a gene is duplicated; one copy still serves the original function, leaving the other gene free to mutate into a slightly different form, enabling the monkeys to get more nutrition from leaves.

In the first case the formal quantity of information is the same, but the effective quantity is different. The second case is information "created" by a non-intelligent mutation. Just because human information is always intelligently caused doesn't mean that biological information has to come from intelligence.

Using Dembski's Hamlet analogy leads you to miss the fact that information is more than just a mathematical description.


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