Since the Cologne sex attacks, there has been even more of a backlash against immigration in Europe. Whilst the details of those attacks are unclear, I wonder: might increased crime be the price we must pay for doing our moral duty?

I ask because of some new research (pdf) from Switzerland. It estimates - based on migration to Switzerland -that:

Cohorts exposed to civil conflicts/mass killings during childhood are on average 40 percent more prone to violent crimes than their co-nationals born after the conflict.

This rings true. We know that people are scarred by experiences in their formative years and that there is an intergenerational transmission of violence. As Glen Bramley points out, British adults who are chronic offenders "had very high instances of adverse childhood experiences". It is surely, therefore, plausible that people who suffer the trauma of civil war and mass killings in their early years will themselves be disproportionately predisposed to violence.

But these are precisely the people we have a duty to help. The principle of luck egalitarianism tells us that it is unjust for people to suffer through no fault of their own - and it is not one's fault if one suffers mass violence in one's childhood. To condemn people to suffer because of a misfortune of birth is to revert to feudalism.

From this perspective, the claim that migrants are prone to violence - far from being a reason to exclude them - is in fact a reason for letting them in. It is those who have been most traumatized in their youth that we have a duty to help - but equally, it is these people who are prone to violence. If our immigration policy is at all humane, it will increase the domestic crime rate.

You might reply that our duty to help the world's most traumatized people is trumped by a duty to reduce the threat of crime to "our own people." Nations, however, are imagined communities. It is not self-evident that our duties to our co-nationals outweigh our duties to the very worst-off: the claim that they do requires cool-headed philosophical argument, not hysterical populist shrieking.

In this sense, we have a fundamental trade-off - between a duty to rescue people from civil wars and mass violence on the one hand, against curbing crime on the other.

But this trade-off can be mitigated. The very fact that violent crime has fallen in many western nations since the 1990s tells us that cycles of violence can be broken. The way to do so is to give work to asylum-seekers: common sense tells us that men are less likely to commit crime if they have something to lose (such as a job) by doing so. In fact, that Swiss research finds that:

getting labor market policies right can wipe out any crime-fuelling impact of past exposure to conflict.

Wouldn't this (slightly) bid down the wages of native workers? It wouldn't, if it were accompanied by serious full employment policies. Perhaps, then, proper macroeconomic policies have even bigger pay-offs than people think, as they would also help reduce anti-immigration feelings.