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Comment by ZeroGravitas | Hacker News Reader

It's not a small incentive though. It's a toy model where the only thing that the agent cares about is how many of his neighbours are the same color as him. Every single person in this model society will immediately move house if 1/3 of their immediate neighbours are the wrong color and not move to any such neighbourhood for any reason, since there are no other motivations in the model.

Which apparently was considered a 'mild' preference by the person who made the model, in the middle of the civil rights era.

It basically renders any immigration inpossible for example, is that really a mild preference?

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You are referring to Schelling's model, and the threshold he found for segregation wasn't 1/3 but 2/3 'wrong', i.e. that everyone prefer not to be in a minority of less than 1/3. This was just was striking about it – that even if every individual is happy with being in a minority, the population can still segregate. I'm not aware that he ever referred to the degree of preference in his model as 'mild', or small. It's relatively small, compared to what you might otherwise expect – I think most people would have guessed that it took a preference of 1/2 to produce self-segregation.

I think my point still stands.

People will move for one reason only, when they are in a 1/3 minority or smaller, and when they move they will only move to a place where they are not in such a minority, which alters the balance for the other people living there causing the chain reaction.

It's a neat mathmatical toy, but when you spell out what it's doing it's tautological and obvious, which is cool for maths, less so for social policy.

Is it really that surprising that people might have wanted to model "preferences for segregation" in the middle of the civil rights era? That's when controversial policies such as school busing were started, and the implied argument for those was not very different from the one that's surfaced by this model - segregation was understood as self-reinforcing, and only very strong policy choices could drive a "mixing" outcome.

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