If nothing else, the past two weeks bear witness to the amazing resilience of America's political parties -- not as political or intellectual movements, but as tribes. Ideas come and go -- but what do ideas matter, really? The parties, God help us, endure.
Donald Trump is neither a conservative nor a Republican, as President Barack Obama told the Democratic National Convention on Wednesday. The Republican nominee's program, such as it is, rejects mainstream conservatism in almost every particular. In taking over the party, he ran against it. Yet see how the party accommodated itself to the invader. The Republican National Convention in Cleveland last week celebrated his coronation. Expressions of discontent weren't tolerated, as Texas Sen. Ted Cruz found out: Republicans ditched everything except the imperative to unite against the enemy.
The remolding of the Democratic Party has been less dramatic, but there are similarities. Senator Bernie Sanders stands for a tendency within liberalism, not something entirely outside it, so he isn't the Democratic equivalent of Trump. Even so, the demands of tribal politics have yielded a notable reordering of ideas.