The elected members of the Democratic Party seem to have hit upon a novel form of leadership: not participating. The way we expressed this when we were much younger was, "I'll take my dolls and go home."

It is not much of a governing philosophy, but so pronounced that Daniel Henninger devoted his a Wall Street Journal column to it. Headline: "The Democrats Abandon the Ship of State."

The Democrats' behavior at the end of President Trump's address to a joint session of Congress Tuesday night was symbolic of what they have adopted as policy:

That scene you saw at the moment President Trump ended his speech to a joint session of Congress was the Democrats abandoning the ship of state.

Like the progressive street demonstrations endured by the country the past four weeks, we may assume Congress’s Democratic delegation organized their post-speech bolt to the exits via the famous social-media hashtag #TheResistance.

During the speech’s most extraordinary moment, the tribute to Carryn Owens, wife of slain SEAL Ryan Owens, one notable Democrat who refused to stand was Rep. Keith Ellison, who just lost a close race for Democratic National Committee chairman to Obama Labor Secretary Thomas Perez, also a man of the left.

You’d have thought that at the two-thirds point, when Mr. Trump hadn’t self-destructed as expected, when instead he was looking less like Alec Baldwin and more like President Trump, that Chuck Schumer might have pulled out his smartphone to tweet the troops, “Walkout maybe not a good idea.” Not this crew. En masse, they went over the side, just as they’ve refused to attend hearings for cabinet nominees and voted as a bloc against virtually all of them.

It's been customary to say that the Democrats in Congress have been shoved into this stance by their angry base. I dunno. Some of the ladies in white seemed to be having a heck of a time giggling and doing a gladiator thumbs down during the president's address. In other evidence that the Democrats are beginning to look a lot like high school, activists petitioned Senator Chuck Schumer, minority leader, to drop West Virginia Senator Joe Manchin from his leadership role as punishment for voting to confirm Scott Pruitt to the EPA. Trump carried Manchin's coal-producing state by 42 points.

Some of us (I plead guilty) have been having a few laughs about the Democratics' behavior during the speech and in general. But one party's simply withdrawing from participation in the normal procedures and traditions of government is not funny. We need two parties to ensure that the other party doesn't get carried away. Think how healthcare reform might have been different if the Democrats had welcomed Republican participation in developing a system instead of using a historic opportunity to ride roughshod over the other party. How's that working out?