Kate Raworth’s doughnut didn’t come out of a bakery. It is her playful way of helping us recognize that there is a safe space, between making life good for all through a strong social foundation, and exceeding our planet’s ecological limits, in which we can all live well.

And it is an idea that has caught on with a lot of cities, because it brings two main societal categories – social problems and environmental problems – together in one framework. If the social foundation isn’t in order, too many people face poverty, loneliness or housing problems; but if housing prices help determine the city’s economic performance, it might look like the city is doing well but high prices mean many people can’t afford a house, says one of the people involved in Amsterdam’s doughnut planning.