By Paul Ormerod
The political map of London is like the United States, with strong geographic segregation. But is there something more subtle going on?
Thomas Schelling is a brilliant American polymath, who deservedly won the Nobel Prize in economics in 2005. One of his most remarkable insights is about segregation in cities, which he published as long ago as 1971.
The residential pattern of American cities tends to be pretty sharply divided on ethnic grounds. The population of many areas is often overwhelmingly drawn from a single ethnic group. There are white neighbourhoods, black neighbourhoods, as so forth, in which there are very few members of other ethnic groups.
An obvious implication of this seems to be that there is strong racial prejudice in the US, that many people actively prefer to live amongst people of their own ethnicity.
Schelling showed that strong segregation at the level of the city as a whole can arise even when individuals have only a very weak preference in favour of being surrounded by people of their own ethnic group. There is a big, often highly mathematical, scientific literature on this in the four decades since Schelling made his discovery. But his basic finding still remains valid. Very weak individual preferences often translate into apparently very strong ones at the city-wide level.
His work was all the more remarkable given that personal computers had not been invented. Schelling obtained his results using coins on graph paper. He placed pennies and nickels in different patterns on the “board” and then moving them one by one if they were in an “unhappy” situation.
The first preferences in the 2012 London Mayoral election are a remarkable example of city-wide segregation. They give the impression of a city which is sharply divided in its political allegiances and outlook.