A depressing feature of the Brexit debate is the way that it goes round in circles. No sooner has an argument apparently been settled than it reopens again.

One example is the persistence of the idea that the U.K. should join the European Economic Area as a way to avoid the inevitable Brexit cliff edges. The so-called Norway option—which would see the U.K. join an outer tier of countries alongside Norway, Iceland and Liechtenstein that are inside the single market, but outside the European Union’s customs union—continues...