David Cameron said something interesting about immigration yesterday:

People have understandably become frustrated. It boils down to one word: control. People want Government to have control over the numbers of people coming here.

Let's leave aside the fact that Cameron himself has added to this frustration by not delivering upon his promise to reduce immigration. I suspect that, in these words, Cameron has highlighted why economists and the public differ so much about immigration.

We economists are pretty sure that, except perhaps for a small adverse effect upon the least skilled, immigration has been a net benefit (pdf) for the economy.

But this doesn't convince most people. Instead, as Ben says, many have an inchoate and inarticulate feeling that immigration might disrupt their sense of home: the fact that people are (generally) most worried about immigration in areas where there is least immigration is entirely consistent with with feeling: uncertainty is often greatest where hard knowledge is lowest. They want "control" because this would reduce the uncertainty they feel.

And herein, perhaps, lies the reason for the difference between economists and the public. We economists are aware that uncontrolled processes - what Hayek called spontaneous order - often have benign effects. Yes, free markets sometimes fail. But they very often work.

Non-economists, however, are less aware of this. It might be no accident that those who are most worried about immigration also favour greater state intervention in the economy generally: 83% of Ukip voters think (pdf) the government should control prices and big majorities of them support nationalization. Adam Smith spoke of the "invisible hand" for a good reason - because people cannot see the adjustment mechanisms which ensure that a benign order often arises from processes which are not controlled by conscious human agency. Here's Hayek:

Some persons are so troubled by some effects of the market order that they overlook how unlikely and even wonderful it is to find such an order prevailing in the greater part of the modern world, a world in which we find thousands of millions of people working in a constantly changing environment, providing means of subsistence for others who are mostly unknown to them, and at the same time finding satisfied their own expectations that they themselves will receive goods and services produced by equally unknown people. Even in the worst of times something like nine out of ten of them will find these expectations confirmed.
Such an order, although far from perfect and often inefficient, can extend farther than any order men could create by deliberately putting countless elements into selected `appropriate' places. (The Fatal Conceit (pdf), p84.)

This, I suspect, accounts for the difference between economists and most of the public; economists have a greater presumption than the public than uncontrolled processes are a good thing.

But is this presumption correct? I'm pretty sure it is in the economic sphere. But what of the non-economic sphere, that feeling of "home" of which Ben wrote? Again, my hunch is that the presumption is correct: the integration of Jews, West Indians and Ugandan Asians is strong empirical evidence that immigration enriches society, and that fears of it are due to the reification fallacy.

There is, though, a counter-argument here. Inductive reasoning is dubious: just because something has worked in the past doesn't mean it will continue to do so. And we have a reason to fear it mightn't. Spontaneous order isn't always benign. Markets do sometimes fail. And Marxists and feminists can reasonably argue that patriarchy and capitalist exploitation are also examples of spontaneous order.

I don't know for sure whether this counter-argument applies. The question of whether spontaneous emergent processes are benign or not depends upon context. I suspect, though, that this is the unspoken issue that underlies much of the immigration debate. In drawing attention to this, Mr Cameron has been admirably insightful.