Ian Duncan Smith's suggestion that ghettos of poor quality housing were a factor in the summer riots has reignited the debate over the causes of the London riots.
When I wrote about this in the summer, I said: "the economics literature tells us that separating out whether individual or community factors drive rioting is incredibly difficult. This suggests we should be very wary about believing anyone who claims to know otherwise." To be fair, Duncan Smith was suggesting only that poor quality housing might be one factor. This is one of many hypothesis worth considering. However, as many people who live in poor quality housing are poor it will be hard to know whether poor quality housing or poverty (or both) were responsible. In short, this is just a concrete example of the more general problem of distinguishing between individual and community factors as causes of the riots.
For those of you who want to read more here is the rather heroic effort of the Guardian to get to the bottom of this question in a single day and here is my discussion on some of the policy implications.