Natural Experiments

This was fascinating:

Their answer is yes: when urban life revived in the medieval period, French towns tended to be near old Roman centers, while British towns didn’t. And the British had the better of this deal, because optimal town locations in the Roman era — with good roads — weren’t the same as in the Middle Ages, when roads remained terrible but the technology of water transport had improved.

 Which says all sorts of things about how it might actually be possible to improve things in a rather dramatic way by asking some tough questions.