In the (very) long run, we are all equal
Nick Clegg has just said the promotion of social mobility is the 'central objective' of the coalition's social policy. Yet some fascinating recent economic research suggests that he needn't bother. Apparently, England already has complete social mobility. It just takes a really, really long time.
The paper, by the US-based economic historian Gregory Clark, finds that, eventually, the descendants of today's England's elite families will stop having an in-built social advantage, and the descendants of poor families will lose their social handicap: there are no permanent social classes, and all groups are regressing to the social mean."
That is the good news. The bad news is that it's likely to take about 350 years, and there's not much the government can do to speed the process up.
"The huge social resources spent on publicly provided education and health have seemingly created no gains in the rate of social mobility," argues Prof Clarke.
"The modern meritocracy is no better at achieving social mobility than the medieval oligarchy. Instead, that rate seems to be a constant of social physics, beyond the control of social engineering."
In fact, the research implies that the only reliable way to increase social mobility in this country would be for the government to force people to marry people from a different social class - ideally someone from a different ethnic group. Presumably, that is not part of Mr Clegg's plan.
Prof Clark uses rare surnames to trace families in England back to the Domesday book in 1086, some starting out "rich", others "poor". In the long run, he finds that "elites are unable to protect their position, and with enough time fall to average status. For the English class is, and always was, an illusion".
Most "Smiths", for example, are descended from the village blacksmiths of the 14th century. By 1650, the author finds as many "Smiths" in the top 1% of wealth holders as in the general population. They are completely absorbed into the elite. But as the example shows, the long run is pretty long.
Depressingly, perhaps, the rate of mobility does not seem to have been any higher in the 20th century than it was in the 1300s. Indeed, by some measures, children from poor backgrounds had a better chance of advancing in society in Medieval England than they do now (though their life expectancy now is obviously a lot higher, whichever class they are in).
Prof Clark finds that people with "rich" surnames from 1858 are still more than four times wealthier, on average, in 2011 than people who descend from the "poor" families of that era. At the current rate of mobility, it will take at least another 100, maybe 200, years for the descendants of these 19th century "rich" and "poor" families to revert to the average. He thinks it could take even longer for today's disadvantaged groups to get ahead, because so many are from immigrant groups who may find it harder to become accepted in the social mainstream.
There are several intriguing conclusions for Mr Clegg - and anyone else who hopes to raise social mobility in the UK. One is that it's going to be very difficult to make progress in our lifetimes, let alone the lifetime of the parliament.
The deputy prime minister seems to be very well aware of this; indeed, he said as much in today's parliamentary debate.
But there's an even more inconvenient truth highlighted by this study - in a modern society, social mobility and "fairness" are not necessarily the same thing.
In the debate, Mr Clegg said that "in a fair society, ability trumps privilege". That is what we like to think. But when you step back to look at social mobility across the generations, you see that ability and privilege are quite often the same thing.
According to Prof Clark: "Most of the strong correlation of wealth across generations does not come from direct transfers of assets from parents to children... Rich fathers have rich sons mainly because the sons are inheriting other characteristics of the fathers, such as their genetics, which are transmitted independently of how many surviving children father's have at death".
The link between ability and privilege is only likely to increase as intelligent, successful men have children with intelligent, successful women. Indeed, if you believe that intelligence is strongly genetic, the only hope for a "fair" society, by Mr Clegg's definition, is for rich intelligent people consistently to marry comparative thickos. Indeed, the fact that significant numbers of them do precisely that is the main reason why privileged families do, eventually, revert to the mean:
"If the main determinants of economic and social success were wealth, education and connections then there would be no explanation of the consistent tendency of the rich to regress to the society mean. Only if genetics is the main element in determining economic success, only if nature trumps nurture, is there a built-in mechanism that ensures the observed regression. That mechanism is the intermarriage of the rich with those from the lower classes. Even though there is strong assortative mating [people marrying people who are similar to themselves], since this is based on the phenotype created in part by chance and luck, those of higher than average innate talent tend to systematically mate with those of lesser ability and regress to the mean."
It's not a new problem. But it is a large one for a government that has made increasing social mobility the "central objective of [its] social policy".
We might, just might, be able to create a socially mobile society, in which poorer children have just as good a chance of rising to the top as people from richer families. But for more of the bottom to rise, the children of people like Nick Clegg need to be able to fall. And places like Oxford and Cambridge would have to be given very tough limits on the number of young Cleggs and Harmans they could admit, even if they were very brainy indeed.
Or, the government could try to create a society in which "ability" trumps everything else. So the cleverest people go to the best colleges, regardless of background or wealth.
Successive governments have tried - and failed - to achieve both of these worthy objectives. But it's not clear that they are mutually compatible. It's even less obvious which is more "fair".