The death of Supreme Court Justice Antonin Scalia has given rise to yet another crisis in the United States. These days, when it comes to governing, America seems to be in a continual state of crisis. And, Paul Krugman writes, the reason can be laid squarely at the feet of the Republican Party:

On the substantive divide between the parties: I still encounter people on the left (although never on the right) who claim that there’s no big difference between Republicans and Democrats, or at any rate “establishment” Democrats. But that’s nonsense. Even if you’re disappointed in what President Obama accomplished, he substantially raised taxes on the rich and dramatically expanded the social safety net; significantly tightened financial regulation; encouraged and oversaw a surge in renewable energy; moved forward on diplomacy with Iran.

Any Republican would undo all of that, and move sharply in the opposite direction. If anything, the consensus among the presidential candidates seems to be that George W. Bush didn’t cut taxes on the rich nearly enough, and should have made more use of torture.

There is a fundamental divide between the two parties. And that’s because one of the parties has descended into lunacy:

Beyond that, there are huge differences in tactics and attitudes. Democrats never tried to extort concessions by threatening to cut off U.S. borrowing and create a financial crisis; Republicans did. Democrats don’t routinely deny the legitimacy of presidents from the other party; Republicans did it to both Bill Clinton and Mr. Obama. The G.O.P.’s new Supreme Court blockade is, fundamentally, in a direct line of descent from the days when Republicans used to call Mr. Clinton “your president.”

Now the Republicans are claiming that Barack Obama has no right to nominate someone to the Supreme Court in the last year of his presidency — although that’s precisely what Ronald Reagan did in the last year of his presidency. Twenty years later, Anthony Kennedy is the only swing vote on the Court. How long is the Court supposed to remain evenly divided?

And, after the last Republican debate — which seemed to continually return to the refrain, “You lie” — you have to ask yourself, are these people capable of governing the most powerful nation on earth?