‘Pick the target, freeze it, personalise it and polarise it.’ This is the best-known of Saul Alinsky’s Rules For Radicals, and even if you haven’t heard of the man or the book, you’ll be familiar enough with the technique. We saw a classic example a couple of weeks ago: the way that off-the-cuff remark on Keynes by Niall Ferguson was seized by his enemies on the left to ‘expose’ him as a wicked homophobe.