and knows more about economic theory, which interests him. He has his own views on the world. So I invited him to write a blog post on a topic of his choosing. Here it is: by Matthew Ridley Janice Turner provided an amusing dose of irrational pessimism in TheTimes on 21 August (behind a paywall) with an argument for population control. Talking of China's efforts to control population, she says that: John Gray, in his review of my book The Rational Optimist accuses me of being an apologist for social Darwinism. This vile accusation could not be farther from the truth. I have resolutely criticised both eugenics and social Darwinism in several of my books. I have consistently argued that both policies are morally wrong, politically authoritarian and practically foolish. In my new book I make a wholly different and more interesting argument, namely that if evolution occurs among ideas, then it is ideas, not people, that struggle, compete and die. That is to say, culture changes by the mutation and selective survival of tools and rules without people suffering, indeed while people themselves prosper. This is precisely the opposite of social Darwinism in the sense that it is an evolutionary process that enables the least fit people to thrive as much as the fittest. Let nobody accuse professional healthcare officials of being unproductive. They diligently produce what they are good at producing -- dire warnings of disaster. There have been Ebola virus, Lassa fever, swine flu, bird flu, swine