I recently did something that is, in theory, most unwise: I bought a second-hand car. Since economists hate to compromise between safety and style, it was a Volvo. You'd think I would know better. The American subtitle of my book is "Why you can never buy a decent used car".

In 1966, an assistant economics professor, George Akerlof, tried to explain why this is so in a working paper called "The Market for Lemons". His basic insight was simple: if somebody who has plenty of experience driving a particular car is keen to sell it to you, why should you be so keen to buy it?