Ordinarily, I'm in favour of philosophical reflection. Without it, ideas such as fairness, freeddom and democracy risk becoming empty politicians' cliches. However, I fear the philosophical debate between Norm and Paul about value pluralism is not going to be fruitful.

Paul says:

There are other worldviews, which do not depend on the primacy of the individual, which are potentially as valid.

Norm replies:

If other views not depending on the primacy of the individual may be as valid as liberal values and a belief in human rights, then a community which every now and then drops some of its members into a large meat grinder is fine.

This doesn't get us far. Can I try a different line? Rather than use philosophy, why not appeal to facts about people's preferences instead? If liberal values are better than other ones, we'd expect to see people migrate to countries with such values. If they are not, we'd expect no such pattern.

The World Bank has data on this. They show that, with one exception which we'll come to, people tend to migrate from states with poor human rights records to states with better ones. In 2010 there were 993,729 Cubans living in the US, but only 522 Americans living in Cuba. There were 66,612 Iraqis living in the UK, but only 947 Brits living in Iraq. And so on.

Generally speaking, countries with poor human rights records have more emigrants than immigrants. For Cuba, the ratio is 79.9 to one. For China, 12.2 to one, for North Korea 8.1 to one, for Iraq 18.6 to one. Countries with liberal values, however, have more immigrants than emigrants. For the US, the ratio is 17.7 to one, for Sweden 4.1 to one, for Australia 12.5, for France 3.8.And so on.

These ratios understate people's preferences for liberal values, for three reasons. One is the home bias; people prefer to stay at home, and only up sticks if things are much better elsewhere. Another is that liberal nations give people opportunities to emigrate, partly because they educate them better, thus making them attractive to potential hosts; partly because in Europe liberal nations are close to each other, thus facilitating migration; and partly because liberal nations permit migration in a way that, say, North Korea does not. And thirdly, of course, there are immigration controls in most western countries. If all nations were to open their borders, would Cubans migrate to the US, or Americans to Cuba?

You might object here that people don't migrate towards countries with liberal values but towards rich ones. Evidence for this is that the main exception to my pattern is that oil-rich Arab nations have high net immigration.

But I'm not sure how much weight this objection has. It is surely no accident that rich countries tend overwhelmingly to have either liberal values or oil wealth - because these are pretty much the only ways of becoming rich*.

With the exception of economic migration to oil-rich states, then, the figures show a clear fact. People of all cultures seem to prefer to live under liberal values than not.

Of course, this preference might be wrong. Maybe people are deluded in preferring liberal values. Maybe they regret migrating. Unless you can produce strong evidence for this, however, there is a more natural inference. It is that whilst we might not be able to prove philosophically that liberal values are superior, there seems to be intercultural subjective agreement that they are.

* China is NOT an exception to this. Its GDP per head is only around $8400, a quarter of the UK's.