We face a terrible choice. Republicans argue that the rush to impeachment aims to overturn the 2016 election. True. They say this is bad for U.S. democracy. Also, true. One reason is legitimacy. What sustains successful democracies is the belief by winners and losers that they had a fair shot at winning. Faith in the system is more important than the result of one election. But if you start fiddling with the outcome — changing the result — you destroy this belief and put democracy at risk.

Because I respect this logic, I am an uneasy advocate for impeachment. If Americans don’t like their government, they can elect a new one. This is how mature and stable democracies are supposed to work. But there is at least one major exception: a situation in which the president’s behavior itself is so erratic and disconnected from underlying realities that it poses an immediate threat to the country. This is mostly a matter of judgment, but I conclude that Trump has landed us in this unfortunate spot. What might he do next?

The lesson of the Syrian debacle is that Trump is increasingly impervious to outside evidence and influence. No one knows what he will do, except that, reflecting his background as a reality-TV star, he aims to dominate the daily news cycle every day. This means he constantly needs new and more incendiary material. He incites his “base,” because he’s good at it and enjoys it. Inevitably, this dragged him toward impeachment.