Donald Trump does not surprise

It was, instead, a window into an essentially sub-rational and self-sabotaging mind (as were the tweets that swiftly followed), whose obsessions make it impossible for Trump not to act on impulse, whose grievances constantly override the public interest and political self-interest both.

But it was not a new window: This same self-destructiveness was evident at every turn in the campaign. So the only mystery is why otherwise-rational Republicans persist in hoping for anything save chaos from a man who celebrated clinching the nomination by accusing his rival’s father of having had a hand in killing J.F.K.

Similarly mysterious, meanwhile, is the assumption among liberals that Trump’s behavior must be motivated by some dark but ultimately rational calculus — that if the president fired Comey in part out of annoyance at the Russia investigation, there must be some great conspiracy he’s desperate to cover up, which if brought to light would make impeachment a near-inevitability.

Of course there might be such a conspiracy, which is why the F.B.I. investigation must proceed — and even if it only exposes shady business ties it’s entirely worth pursuing. But given what we know about Trump’s personality, what’s in the public record, and what’s been leaked by forces with reasons to despise him, Occam’s razor still suggests that shadiness is all we’ll find, and that Trump is lashing out childishly not out of guilt but because that’s simply what he does — whether the target is Ted Cruz’s family or Judge Curiel, the Khan family or now Comey.