Imagine, if you will, that George W. Bush had started acting like Donald Trump partway into his second term. I won't even discuss the stuff that's disputed, like dropping high-level intel into a conversation with a rival power, or asking the FBI director to stop investigating a former aide, in the casual manner that a shady small-city mayor might attempt to fix a friend's traffic ticket.
No, let's just look at the things we know our president has done recently, such as summarily firing the head of the FBI by sending a note over to FBI headquarters while the director was out of town. Sending his staff to make claims about the firing that he then idly rebutted on national television, while simultaneously opening himself up to charges of obstructing justice.
Getting on Twitter to try to blackmail that FBI director into keeping mum about it all, and in the process inviting congressional subpoenas of the possibly mythical tapes he mentioned in that tweet. Blaming his staff for failing to put out the dumpster fire he started.
Saying at a U.S. Coast Guard Academy commencement that no politician in history has been treated as unfairly as him. Going back to Twitter to complain about the appointment of a special counsel to investigate his administration, in the process misspelling "counsel" and proclaiming "This is the single greatest witch hunt of a politician in American history!" (Gov. Scott Walker, R, Wis., probably begs to differ.)
Is there any question that people would be talking about invoking the 25th Amendment to remove him? Not for political reasons, but because it would be obvious that some tragic mental impairment had befallen the commander in chief.
Adults of mature years know not to engage in histrionic self-pity in public, not necessarily because they avoid self-pity, but because outside of high school parties, this is a singularly ineffective way to make people like and support you.
Competent leaders do not preside over staff who are leaking what is essentially one long and anguished primal scream to any reporter they can get to hold still. Seasoned professionals do not, suddenly and for no apparent reason, say things in public that make them better targets for legal investigations.
If they want to threaten someone with blackmail, they do it in hushed tones and empty rooms, for the act's very name tells us that it is an art best practiced in the dark.
And so the only possible explanation for such a quick succession of stunning lapses in judgment would be a severe stroke, an aggressive brain tumor or some other neurological disaster that had rendered him unfit to continue in office, at least until it could be treated.
I don't even think this would be controversial, even among his supporters. "Poor fellow," they'd murmur, "the strain of the office has destroyed his health. He has given more than his life for his country." Time to let him rest and heal while someone else shoulders his Sisyphean burdens.
So why was it so controversial when Ross Douthat recently suggested in The New York Times that it was time to start thinking about that 25th Amendment? Only because Trump's public unraveling has taken place so quickly — which is to say because this was, pretty much, how he acted before he took the oath of office.
Trump has always said the kinds of things that most of us learn to think the better of around our freshman year of high school — not just the tragic wailing about how hard everyone is on him, but also the needy self-flattery: When he isn't claiming he knows more about Islamic State than our nation's generals do, he is putting similarly laudatory words in the mouths of the brilliant and impressive people who apparently constantly ring him up so they can gush like tween fangirls at a Justin Bieber concert.
Does he expect people to believe these utterances? I have no idea. But the reason most people don't say such things is that whether you expect them to or not, no one ever does.
As for the rest … the Twitter rants? Check. The lack of respect for long-standing political and institutional norms? Check. The outrageous, uncalled-for attacks on anyone who gets in his way? Check-plus. All quite evident before the American public went to the polls in November. And that is the rub.
It's one thing to remove a president who is clearly no longer the man (or woman) we elected to the office. But this is what Americans, in aggregate, pulled the lever for. Do his staffers and Congress have the right to step in and essentially undo that choice?
Even as a thought experiment, that's a tough question. It becomes much tougher still when we are not in a tidy textbook, but in a messy real world where his followers, having voted for this behavior, do not recognize it as a sign of impairment. If Trump is removed now, they will see the removal not as a safeguard, but as a soft coup. And they won't be entirely unjustified. The damage to our political culture, and its institutions, would be immeasurably grave.
I think there's a case for removing Trump on the grounds he is clearly not competent to execute the office — not that he has committed "high crimes and misdemeanors," but that he simply lacks the emotional and mental capacity to do the job.
But preserving the very norms he's destroying requires that removal not be undertaken until things have reached such a state that most of his followers recognize his problems.
So those of us who believe the competence of the executive matters — there are things worse in a president than "more of the same," and what we are now seeing is one of them — will simply have to hope like heck his supporters come to the same conclusion we have before he damages much more than his own reputation, and the hopes of the people who elected him.
Megan McArdle is a Bloomberg View columnist. She wrote for the Daily Beast, Newsweek, the Atlantic and the Economist and founded the blog Asymmetrical Information. She is the author of "The Up Side of Down: Why Failing Well Is the Key to Success."