Tim Harford has [a column in the Financial Times claiming that citizenship matters more than class for inequality](http://www.ft.com/cms/s/0/d9cddd8e-6546-11e4-91b1-00144feabdc0.html). In many ways it isn’t a bad piece. I give him points for criticizing Piketty’s default assumption that the nation-state is the right unit for analysis. The trouble with the piece though is the immediate inference from two sets of inequality stats to a narrative about what matters most, as if the two things Harford is talking about are wholly independent variables. This is a vice to which economists are rather prone.

Following Branko Milanovic, Harford writes:

> Imagine lining up everyone in the world from the poorest to the richest, each standing beside a pile of money that represents his or her annual income. The world is a very unequal place: those in the top 1 per cent have vastly more than those in the bottom 1 per cent – you need about $35,000 after taxes to make that cut-off and be one of the 70 million richest people in the world. If that seems low, it’s $140,000 after taxes for a family of four – and it is also about 100 times more than the world’s poorest people have. What determines who is at the richer end of that curve is, mostly, living in a rich country.

Well indeed, impressive stuff. And as Joseph Carens noticed long ago, and Harford would presumably endorse, nationality can function rather like feudal privilege of history. People are indeed sorted into categories, as they were in a feudal or class society, that confine them to particular life paths, limit their access to resources and so forth. But there’s a rather obvious point to make which rather cuts across the “X matters more than Y” narrative, which is that citizenship isn’t a barrier for the rich, or for those with valuable skills. It is the poor who are excluded, who are denied the right to better themselves in the wealthy economies, who drown in the Mediterranean, or who can’t live in the same country as the love of their life. Citizenship, nationality, borders are ways of controlling the mobility of the poor whilst the rich pass effortlessly through. It isn’t simply an alternative or competitor to class, it is also a way in which states enforce class-based inequality.