All good meals, and all books, must come to an end. It would be wrong, however, to disappear into the night without a chat, perhaps even a little debate. Economists argue all the time. The subject advances, or sometimes goes back a little, by means of constructive engagement. To some, economists disagree a little too much. Churchill famously said that if you had two economists in a room you were guaranteed two different points of view, ‘and three if one of them is Mr Keynes’. That may be a little too harsh. Where would we be without controversy? The comforting thing about economics, indeed, is that it is often possible for both sides to be right. With this in mind, let us have a look at some longstanding controversies.