One of the most obvious (and ubiquitous) lies in American political rhetoric is that the United States is the only country where poor kids sometimes grow up to become wealthy politicians.

“I live in an exceptional country where even the son of a bartender and a maid can have the same dreams and the same future as those who come from power and privilege,” Marco Rubio said when he launched his presidential campaign last year. Barack Obama has similarly claimed that his own story of upward mobility would have been possible “in no other country on earth.”

But even as our leaders assure us that only America has escaped the grip of feudal rule, study after study has shown that bartenders’ sons born in Canada and Western Europe have a better chance of growing up to see bartending as a lowly profession than ones born here.

The tension between our self-conception as an exceptionally meritocratic society — and the reality that America’s deep poverty and threadbare social safety net makes it exceptionally socially immobile — is reflected in the bipartisan obsession with restoring “equality of opportunity.”