Almost everyone agrees that raising taxes on the middle class in the middle of an economic slump is a bad idea, unless the effects are offset by other job-creation programs — and Republicans are blocking those, too. So the G.O.P. is, in effect, threatening to plunge the U.S. economy back into recession unless Democrats pay up.

What kind of political party would engage in that kind of brinksmanship? The answer is the same kind of party that shut down the federal government in 1995 in an attempt to force President Bill Clinton to accept steep cuts in Medicare, and is actively discussing doing the same to Mr. Obama. So, as I said, the deeper explanation of the tax-cut fight is that it’s ultimately about a radicalized Republican Party, which accepts no limits on partisanship.

So should Democrats give in?

On the economics, the answer is a clear no.