What happens to American politics after Donald Trump? Do we snap back to normal or do things spin ever more widely out of control?

The best indicator we have so far is the example of Italy since the reign of Silvio Berlusconi. And the main lesson there is that once the norms of acceptable behavior are violated and once the institutions of government are weakened, it is very hard to re-establish them. Instead, you get this cycle of ever more extreme behavior, as politicians compete to be the most radical outsider. The political center collapses, the normal left/right political categories cease to apply and you see the rise of strange new political groups that are crazier than anything you could have imagined before.

If America follows the Italian example, by 2025 we’ll look back at Trump nostalgically as some sort of beacon of relative normalcy. And by the way, if America follows the Italian example, Trump will never go away.

Silvio Berlusconi first came to power for the same reasons Trump and other populists have been coming to power around the world: Voters were disgusted by a governing elite that seemed corrupt and out of touch. They felt swamped by waves of immigrants, frustrated by economic stagnation and disgusted by the cultural values of the cosmopolitan urbanites.