Before plunging into a vexed question, it’s sometimes wise to point out that one is aware how vexed it is. I haven’t been living in a cave these past few years. Even as I speak, doctoral theses are doubtless being written on ‘identity politics’: whole books have been devoted to what has become very much the topic of the day, and (without always being precise about what we mean by the term) we in the world of politics and the political media sometimes seem to talk of little else.