The view is supported by standard rags-to-riches stories, especially among immigrants, and not only the 19th-century entrepreneurs such as Andrew Carnegie, who gave away almost his entire fortune to good causes, but contemporaries like Donald Trump and Bill Gates. Sure, rewards are distributed very unequally, but at least everyone has the same chance of those rewards. Even children born into poverty can make it in America.

The view that America is a meritocracy inhibits support for progressive reforms. As long as we believe there is equal opportunity we can think people deserve their own success or lack of it. So while European countries need welfare states to offset the unequal chances caused by entrenched class systems, in America we need no such thing: everyone is truly responsible for his or her own success.

However, a slew of recent studies by economists and sociologists has confirmed that movement between social classes in America is about the same as in all other wealthy countries apart from Sweden, where social mobility is highest. American children born into poverty are no more likely to become rich than their British counterparts.

According to one study, only 1.3 per cent of children born to parents in the bottom 10 per cent of income earners end up in the top 10 per cent. By contrast, almost a quarter of children born into the top 10 per cent stay there, and almost half stay in the top 20 per cent. Children born into the richest tenth of households are 18 times more likely than children born into the poorest tenth to end up in the top tenth.

Our current President is a brilliant illustration of class advantage. Even his most fervent admirers know that he would not have been admitted to Yale without the affirmative action Ivy League schools operate for the children of alumnae. And no one who failed repeatedly at everything he did into his 40s could have had yet another chance but for the assurance and contacts provided by his family. He is only the most spectacular example of the way that social advantage can compensate for personal defects in life’s great competition. So if America is as class-stratified as Europe, what can be done about it? The traditional meritocratic left has focused on what economists Samuel Bowles and Herbert Gintis dub the “family piano” model.

This assumes advantage is transmitted by wealthy parents buying better education for their children and through gifts and bequests. The solution, on this model, is to tax gifts and inheritance, and improve public education.

But the new studies show this model is wrong, which explains why efforts to improve public education do so little to improve equal opportunity.

Other factors, such as how parents rear their children, and the impact of this on their ability to take advantage of education, seem at least as important as bequests and education. Not only are middle-class children more likely to arrive at school already numerate and literate, but they are more likely to arrive without undiagnosed impairments to learning such as poor hearing and poor distance vision. Their parents are better equipped to negotiate the world of schools when they encounter problems, and a sense of entitlement is inculcated in them.

This makes it especially hard for education to overcome barriers to social mobility. Although some children born into poverty can make their way to the top, we really don’t have any understanding of how schools can systematically educate large numbers of pupils in poverty, especially when those children are raised in neighbourhoods, and sent to schools, almost exclusively with other poor children.

The lesson of the new research is that to create a land of equal opportunity we need to focus attention on equality. Given what we know about the uptake of educational opportunities we should focus on changing the conditions less advantaged children are raised in; making them more like the conditions of others, specifically by abolishing poverty and diminishing inequalities of outcome.

This is not going to be an easy sell. But the example of George Bush’s ultimate success in life makes it a little easier to persuade people.

Harry Brighouse is professor of philosophy and affiliate professor of education policy studies at Wisconsin university, Madison, US