Even those who have long since accepted the premise that Donald Trump is corrupt, self-centered and dishonest seem a bit shocked by his tirades over the Presidents’ Day weekend. Using the Parkland, Fla., massacre as an excuse to attack the F.B.I. for investigating Russian election intervention on his behalf — while lying about his own past denials that such intervention took place — took vileness to a new level, which is truly impressive given Trump’s previous record.

Yet if you step back a bit and think about it, Trump’s latest outbursts were very much in character — and I don’t just mean his personal character. When did you last see a member of the Trump administration, or for that matter any prominent Republican, admit error or accept responsibility for problems?

Don’t say that it has always been that way, that it’s just the way people are. On the contrary, taking responsibility for your actions — what my parents called being a mensch — used to be considered an essential virtue in politicians and adults in general. And in this as in so many things, there’s a huge asymmetry between the parties. Of course not all Democrats are honest and upstanding; but as far as I can tell, there’s almost nobody left in the G.O.P. willing to take responsibility for, well, anything.

And I don’t think this is an accident. The sad content of modern Republican character is a symptom of the corruption and hypocrisy that has afflicted half of our body politic — a sickness of the soul that manifests itself in personal behavior as well as policy.

Before I talk about that sickness, consider a few non-Trump examples of the lack of character that pervades this administration.

At the trivial but still telling end of the scale, we have the tale of Scott Pruitt, head of the Environmental Protection Agency, who keeps flying first class at taxpayers’ expense. The money isn’t the important issue here, although his spending violates federal guidelines. The revealing thing, instead, is the supposed reason he needs to fly premium — you see, ordinary coach passengers have been known to say critical things to his face.

Remember this story the next time someone talks about liberal “snowflakes.”

More seriously, consider the behavior of John Kelly, Trump’s chief of staff, whose record of slandering critics and refusing to admit error is starting to rival his boss’s. Remember when Kelly made false accusations about Representative Frederica Wilson and refused to retract those accusations even after video showed they were false?

More recently, Kelly insisted that he didn’t know the full details about domestic abuse allegations against Rob Porter until, a White House staff member said, “40 minutes before he threw him out” — a claim that seems at odds with everything we know about this story. Even if this claim were true, an apology for his obliviousness seems in order. But these guys don’t apologize.

Oh, and by the way: Roy Moore still hasn’t conceded.

So it’s not just Trump. And it didn’t start with Trump. In fact, way back in 2006 I wrote about the “mensch gap” in the Bush administration — the unwillingness of top officials to accept responsibility for the botched occupation of Iraq, the botched response to Hurricane Katrina, and more.

Nor, by the way, are we only talking about politicians. In my neck of the woods, I remain amazed by the unwillingness of right-leaning economists to admit that they were wrong in predicting that the Fed’s efforts to rescue the economy would cause runaway inflation. Being wrong is one thing — it happens to everyone, myself very much included. Refusing to admit and learn from error is something different.

And let’s be clear: Personal responsibility isn’t dead everywhere. You can ask, for example, whether Hillary Clinton apologized sufficiently for her initial support of the Iraq war or her missteps in 2016 — but she did admit to making mistakes, which nobody on the other side ever seems to do.

So what happened to the character of the G.O.P.? I’m pretty sure that in this case the personal is, ultimately, political. The modern G.O.P. is, to an extent never before seen in American history, a party built around bad faith, around pretending that its concerns and goals are very different from what they really are. Flag-waving claims of patriotism, pious invocations of morality, stern warnings about fiscal probity are all cover stories for an underlying agenda mainly concerned with making plutocrats even richer.

And the character flaws of the party end up being echoed by the character flaws of its most prominent members. Are they bad people who chose their political affiliation because it fits their proclivities, or potentially good people corrupted by the company they keep? Probably some of both.

In any case, let’s be clear: America in 2018 is not a place where we can disagree without being disagreeable, where there are good people and good ideas on both sides, or whatever other bipartisan homily you want to recite. We are, instead, living in a kakistocracy, a nation ruled by the worst, and we need to face up to that unpleasant reality.

<PAUL KRUGMAN>