Purposeless Evolution

Next: Discussion Prev: Darwin/Wallace Prediction TOC

Prior to Darwin, nature was considered a teological (that is, purposeful or intentional) phenomenon. However, Darwin showed that a non-intentionalistic form of explanation was possible. In doing this, he showed not only a new explanation, but he invented a new kind of explanation. He did away with the idea that nature works based on “purpose”. Instead, he showed how nature works in a non-purposeful manner.

In the early nineteenth century, scientists thought the plant moved its leaves for the purpose of maximizing sun absorption in order to survive. In his, Philosophy of Society, lecture 12, John Searle describes how Darwin replaced this with 2 levels of explanation.

First, is the causal explanation of how the plant moves its leaves toward the sun due to the secretion of growth hormones.

Secondly, over deep time, those plants that secrete those hormones and move with the sun are described as more likely to survive than those that do not. So, they proliferate, outnumber and eventually replace those that do not.

Searle more elegantly describes the teleological argument at the 7:28 and 12:32 markers in the referenced lecture. Later, at 13:15, he describes Darwin’s two levels of explanation.

In TGSOE, pp. 351, Dawkins first using a teleological argument.

Evolutionists, on their side, need to come up with an explanation for the loss of eyes where they are no longer needed. Why not, it might be said, simply hang on to your eyes, even if you never use them? Might they not come in handy at some point in the future? Why ‘other’ to get rid of them?

Then, he catches corrects himself.

I should have said something like, ‘How does losing its eyes benefit an individual cave salamander so that it is more likely to survive and reproduce than a rival salamander that keeps a perfect pair of eyes, even though it never used them?’

This is a natural mistake. Human beings want to see purpose in the world around them.

Next, on pp. 352, Dawkins shows how a functional loss can occur due to “deleterious” (or harmful) mutations that are completely random. He also describes how such mutations on eyes will normally be swept away by natural selection pressures but are not in the caves where eyes can’t see anyways.

See also, discussion on Engineering and Design.

Next: Discussion Prev: Darwin/Wallace Prediction TOC