POPULISM is a potent form of democratic politics. Unfortunately, it is also a destructive one, weakening institutions, damaging debate, and worsening policy. It can threaten liberal democracy itself. The Brexit saga is an object lesson in the dangers: it has damaged what was long thought to be among the world’s most stable democracies.

The recent book,What Went Wrong With Brexit: And What We Can Do About It, by my colleague Peter Foster, lays out the story superbly. It shows how a classic populist alliance of fanatics and opportunists mixed simplistic analysis with heated rhetoric and outright lies to weaken the United Kingdom’s most important economic relationship and threaten its domestic stability. Happily, there exists an opportunity to learn from this experience and start putting things right.

Brexit was, in fact, certain to go wrong, because it was based on false premises. Countries cannot be fully sovereign in trade, since it involves at least one counterpart. Thus, the rules of the single market were created because the alternative was multiple different regulatory regimes, and so costlier (and smaller) trade. An institution also had to decide whether countries were abiding by the rules they had agreed. That has been the indispensable role of the European Court of Justice.