Could you explain the idea of toleration and tell us about your first book choice, John Locke’s A Letter Concerning Toleration.

Toleration is an ideal of conduct, which involves putting up with something you find objectionable – you disapprove of it, or you dislike it. You can do that as an individual, or a society can do it, and the ideal is one that’s become pretty well entrenched within liberalism. The reason I started with Locke is because his arguments about toleration are the touchstone of modern discussions of toleration within the liberal tradition. He’s not the first person ever to say anything about toleration – if you look at the history of human beings living together anywhere at any time, you’ll always find examples of people recommending something that looks like toleration, because it’s very hard to see how a human society could go on at all if people refused to put up with the things they disliked or disapproved of. Locke’s argument is capable of being construed in lots of different ways. Some people construe it as a pretty instrumental argument without much positive content, but I would tend to understand it differently from the way in which a lot of contemporary analytical philosophers have taken it.

In what sense?

Well, most philosophers see it as something pretty simple: in their view, Locke’s argument is that it’s futile to try to coerce people into believing something other than they do, because that’s not how belief works. Belief isn’t susceptible to coercion. So it doesn’t make any sense, is irrational, to try to coerce people into believing something other than they currently do.

Let’s talk about Mill and On Liberty.

Mill’s argument is very different in its setting from Locke’s. It’s about what happens when imperatives to religious conformity and uniformity of belief have dribbled away, when hanging and burning are off the agenda. Mill thinks that the space that was occupied by a more or less successfully imposed religious monoculture will be occupied now, if we’re not careful, by a tyranny of majority opinion. His worry is that the everyday prejudices and opinions of ordinary people would become a kind of monolithic structure which gradually pulls everyone into its ambit, such that everyone starts to act and believe and think in the same way.

So is Mill’s idea to guard against some kind of mob rule? Perhaps the kind of outpouring of public opinion that you get when there’s something slightly distasteful?

That’s right up to a point. Mill doesn’t worry overmuch about the mob ruling through politics (most of the mob didn’t have the vote, after all). He takes for granted that the kind of institutional settlement that followed the English revolution of 1688, in which you’ve got the slow development of a constitutional monarchy, will stick – it’s OK, we don’t need to worry about absolute rulers imposing their will on the people, and we need not really fear ‘the people’ imposing their will on everyone else by seizing political power directly for itself, but we do have to worry very much about a mass of people imposing their will on everyone else through society. And it’s that really – the idea that you need to have the liberty of thought and discussion in order to improve society, and to save it from the stultifying effects of uneducated opinion. He thinks that individuality is a good thing in itself, in a romantic way, but also seems to think that by allowing the liberty of thought and discussion, including the liberty to make mistakes, that that has a positive effect overall.