Rising Residential Segregation, but Less Racial Prejudice: How Can This Be?

Britain is becoming more sharply divided on ethnic lines, according to a study just published by the think-tank Demos. During the past decade, more than 600,000 white people have moved out of London to areas which are more than 90 per cent white. The effect is strongest amongst white Britons with children, with a fall of almost 20 per cent in the number of them living in London.

The Demos project is chaired by Trevor Phillips, the former head of the Equalities Commission. At face value, the numbers suggest that racial prejudice is alive and well. It is not just whites who are seeking out white areas. According to Phillips, ethnic minorities are becoming more tightly clustered in areas where their own personal minority is well represented. But Phillips insists that the overall evidence does not show increased prejudice at all. In fact, personal prejudice is declining. How can this be? Prejudice is allegedly falling, yet we are becoming more segregated along ethnic lines in terms of where we live.

The answer to this seeming paradox was provided over forty years ago by the brilliant American academic Thomas Schelling. Schelling, based at the University of Maryland, has carried out highly original work in areas such as national security and nuclear strategy, using a game-theoretic perspective. Along the way, he picked up the Nobel Prize in economics in 2005.

Schelling imagined a checkers (draughts) board, with many more squares than a standard one, on which an equal number of black and white checkers are placed at random. A small percentage of squares are left empty.

The rules of Schelling's game are very simple. One of the checkers is chosen to see if it wants to change location. Each square is surrounded by eight other squares. So including its own square, it looks at nine squares in all to see who else lives in its neighbourhood. Suppose the checker is white.

Provided that in total there are five white checkers in the nine squares, it is happy to stay put. It does not mind living with black checkers on the other four. But if it is 4-5 rather than 5-4, it moves to one of the empty squares.

The players in this game have a very mild preference for living amongst players like them. They are happy to live with a large minority of the other colour.

What happens as the game progresses? Each checker can decide, one at a time whether or not to move. Then they all get another chance to move if they want, given the new pattern of location.

Remarkably, the board segregates very rapidly into dense blocks in which the checkers are all the same colour. It appears as if the players have a very strong preference to live near players of the same kind, which is not the case at all.

Schelling's game is of course highly abstract, but it has profound practical insights. Increased tolerance and increased residential segregation need not be incompatible at all.