James Brokenshire's recent speech on immigration has been widely decried as one of the worst ever. This poses a question: is it possible to make an intelligent case against immigration? Here's how I would try.

The economic evidence tells us that immigration is good for the economy. But economics also tells us something else - that this doesn't much matter. As Andrew Clark says, "the rising trend in GDP per capita is certainly not matched by an analogous movement in average happiness". Whether the Easterlin paradox is really true or only roughly so needn't detain us. What matters is that the welfare gain from economic growth is small.

What does affect well-being, though, is friendship (pdf). Happiness research tells us that this is great for well-being. However, for whatever reason, inter-ethnic friendships are rare, both in the UK and US. I suspect a similar thing is true for nationality; how many of you count Romanians or Bulgarians as friends? This suggests that mass migration might increase social isolation - which matters more for well-being than money.

This point widens. There's some evidence that, at least in unequal (pdf) nations and poor (pdf) communities, immigration can reduce social capital. As Ben says, there might be a link between immigration and the UK's increasingly atomized society.

You might reply that the solution to this is for immigration to occur against a background of greater equality. If more of us were comfortable, there'd be less suspicion of immigrants.

But immigration might, ultimately, erode demand for redistributive policies. One reason for this is that the act of migrating is an individualistic one, and parents might transmit such an individualistic mindset to their children, which would create a culture hostile to collectivism and redistribution. Is it really just a coincidence that the one developed nation founded upon immigration just happens to be the one that historically has lacked a major socialist party or tradition?

Another reason is more unpleasant. It's that ethnic diversity reduces demand for egalitarian policies; people are happier to fund welfare states if the money is helping their "own kind." "Racial cleavages seem to serve as a barrier to redistribution throughout the world" concludes one study (pdf).

All this shouldn't merely worry lefties. It's quite plausible that decent welfare states are good for the wider economy, because they help smooth out macroeconomic fluctuations and so reduce business uncertainty. This could - in the long-run - mitigate the economic benefits of migration.

Now, I'm not sure I subscribe to the above. I've raised issues about the relevance of happiness research; the trade-off between liberty and social capital; the distinction between changes and steady states; and the role (if any) that dirty preferences should play in politics.

But my opinion doesn't matter. My point is that it is possible to make a reasonable argument against immigration which doesn't degenerate into economic illiteracy, racism or sneers at "metropolitan elites." Which kind of makes me wonder why it's so rarely heard.