"I quote somewhere a correspondence with Ken Arrow, after he wrote Arrow and Hahn. I wrote to him and I said that the trouble is that neoclassical economists confuse risk with uncertainty. Uncertainty means non-probabilistic. And he said, 'Quite true, you're quite correct that Keynes is much more fruitful, but the trouble with the General Theory is, those things that were fruitful couldn't be developed into a nice precise analytical statement, and those things that could were retrogressions from Keynes but could be developed into a nice precise analytical statement.' That's why mainstream economics went that route. And my answer is, I would hope that even Nobel Prize winners didn't believe that regression is growth, which it clearly isn't. But that's right. The fear that everybody has, you see, is nihilism: you won't be able to say what's going to happen . Well, evolutionists don't worry about being unable to predict. You ask the evolutionists, who tell you what happened in the past, just what next species is going to appear, and the answer is, anything could. Right? Does that bother people? Explanation is the first thing in science. If you can't explain, you don't have anything. But you needn't necessarily predict. Now, if you know the future's uncertain, what does that mean? It means basically, the way Hicks put it in his later years, that humans have free will. The human system isn't deterministic or stochastic, which is deterministic with a random error. Humans can do thins to change the world."