John Maynard Smith - The point of evolutionary game theory (50/102)

To hear more of John Maynard Smith’s stories, go to the playlist:    • John Maynard Smith - Early childhood and a...   The late British biologist John Maynard Smith (1920-2004) is famous for applying game theory to the study of natural selection. In 1973 Maynard Smith formalised a central concept in game theory called the evolutionarily stable strategy (ESS). His ideas, presented in books such as 'Evolution and the Theory of Games', were enormously influential and led to a more rigorous scientific analysis and understanding of interactions between living things. [Listener: Richard Dawkins; date recorded: 1997] TRANSCRIPT: I think that the point of Evolutionary Game Theory as distinct from Classical Game Theory is that it borrowed a notation from classical game theory, but it's whole logic is quite different. I mean, the logic is fairly easy to explain, I mean, the logic of classical game theory as meant to be applied to human behaviour, simply is to think what would rational human beings do when confronted with a conflict, and this just isn't present in evolutionary game theory at all. The logic of evolutionary game theory is you have a population of individuals adopting different strategies and playing contests against one another, and how successful they are determines how many kids they have, and they pass on to their children their properties. And you look for the dynamics of such a system, and what the evolutionary stable strategy is, is what a mathematician would call a stationary point, or a Stable Stationary Point of the Dynamics. It's what the dynamics will go to. So it's really a totally different notion. But interestingly, the - although the logic is different and so on, the notation has something in common. And the one thing that reading the sort of text books of classical game theory did for me, was to provide me with a notion of a pay-off matrix, which is a very simple notion, and anybody can write down a pay-off matrix once they know what it is. I mean, you just write down a list of the strategies on the bottom and a list of strategies across the top and you have a whole series of entries, and in each hole you put what would the pay-off be to me if I do this and he does that. That's really, I think, essentially all that I took from classical game theory, though I'm now amused to discover that the economists and so on are trying to borrow evolutionary game theory back and introduce it into economics. I'm very unconvinced that they're justified in doing this, because evolutionary game theory hinges on the notion of heredity, i.e. the essential notion being that your success in the game determines how many children you have, and your children are like you, and the whole thing hinges upon that essential assumption. And I can't see that that assumption really holds in economics. [RD] No, the essential point would be that in an evolutionary world, if a strategy is going to stay successful, it's got to do well when it, itself, is in a majority, when it's playing against copies of itself. That's why ESS is so important. Yes, I can't really see how you would import that back into economics. Well, I think they're doing it because - I almost want to say something rude about theoretical economics, which is that it is theoretical. And I have nothing against theory, I've spent most of my life doing it, but I do think the function of theory in science is to explain observations. And if a theory's a bad theory it ought to be possible to point to observations that disprove it. But that just doesn't seem to be the tradition in theoretical economics, it's entirely theoretical, they never refer to a fact. Nobody ever says, oh, this particular economic theory has to be wrong because in the slump or something or other, something happened - I mean, they never refer to a fact. It's pure theory spinning. But I think they looked over the fence and saw that in biology, evolutionary game theory really is explaining a lot of things, from plant growth to virus behaviour to all sorts of things. And they thought, gosh, you know. [RD] And co-operation. And even co-operation, that's right. And they thought, well, maybe we can grab this stuff and steal it back. I'm not sure it's really justified.