Chance, Progress and Complexity in Biological Evolution

The idea of continuous progress occupies an essential place in the personal metaphysics of many of our contemporaries. It is so embedded in their minds that they would have a hard time living without it. This is why the reminder of what evolution owes to chance, coming from certain contemporary biologists and paleontologists like Stephen Jay Gould, is salutory. The recent book by the latter, Full House, forces us to reexamine the applications of the notion of chance in the domain of biological evolution.

This said, we must recognize that the specificity of the living creature, by incorporating in its very genome the history of the presumably victorious variations of its ancestors, draws the evolution of each separately considered branch along a precise trajectory, subject to constraints rooted in its history. If we must repudiate the idea of progress as too tainted by ideology, mustn’t we conclude that these trajectories carry certain living creatures toward an accrued complexity, and across certain thresholds from which they cannot turn back, thereby creating new, emerging qualities?