The Lagoon: How Aristotle Invented Science

by Armand Marie Leroi

His arguments are fascinating, for some of them have been used against the theory of evolution by natural selection. (1) Spontaneous events are rare, but the signature of genuinely purposeful events is that they are common: teeth always come up in exactly the same way. This is a probabilistic argument for the existence of a purposeful agent and, like all such arguments, it is wrong, for selection can regularly produce order from disorder.* Admittedly, Empedocles helps Aristotle to this conclusion by making his cosmogonies indeterminate: ‘[sometimes] it may happen to run one way, but often it ran otherwise’ – the line is quoted by Aristotle. (2) It’s not just the end of development that has the appearance of purpose; it’s also the process. Every step in development is obviously directed towards a final goal, rather like each step in the construction of a house. These steps must be the product of an intelligence that has the final product in mind. (3) Although development is very regular, mistakes do happen (in The Generation of Animals he has a lot to say about conjoined twins and dwarfs), but they are mistakes – deviations from some existing, purposeful programme that must be already in place. Indeed, even Empedocles’ original recombinant animals could not have come from nothing; they must have sprung from ‘some corruption of some principle corresponding to what is now the seed’. (4) Besides, we simply don’t see that much variation. Granted, monstrous progeny sometimes app...