The paranoid style in American politics, as the historian Richard Hofstadter labelled it, has deep roots. So does what one might call the hysterical style in American politics—in which no analogy (Hitler! Slavery!) is too outrageous, no prediction (Ruin! Death!) too dire, and no personal role model (Churchill! Jesus!) too exalted to deploy. Clearly, we are living through a golden age of American hysteria. The present apoplexy over the Affordable Care Act—the proximate cause of this government shutdown—is, by historical standards of hysteria, really first-rate stuff. The shutdowns of the nineteen-nineties seem half-hearted and tentative compared to this one. We haven’t heard shrieking like this since the nineteen-sixties, or possibly since the thirties, when the Republican Party waged a fierce, if futile, assault on the New Deal. Yet, in contrast to our current crop, that era’s conservatives—whose cries of “socialism” have a modern ring—now look like rational actors, exemplars of sweet reasonableness.

When Congress debated the Social Security bill, in 1935, hysteria on the right ran high. The business lobby, echoed by its Republican allies on Capitol Hill, charged Franklin Roosevelt with a plot to extinguish liberty in America—to establish “socialistic control of life and industry,” as the National Association of Manufacturers put it. “Never in the history of the world,” declared Rep. John Taber, of New York, after what one trusts was a thorough review of the history of the world, “has any measure been … so insidiously designed as to prevent business recovery [and] to enslave workers.” To another New York congressman, James W. Wadsworth, Social Security represented “a power so vast” that it threatened to “pull the pillars of the temple down upon the heads of our descendants.” Still, its opponents in the House, and later the Senate, buckled in the face of popular opinion, swallowed their hatred of Roosevelt, and the Social Security Act passed by wide margins.

Another wave of panic crested on the eve of the 1936 election—an eleventh-hour attempt to seize on public anxiety about the Social Security payroll tax, slated to take effect on January 1, 1937. The Republican nominee, Governor Alf Landon of Kansas, called the program “unjust, unworkable, stupidly drafted and wastefully financed.” He and his campaign raised the specter of mass fingerprinting, of Washington snoops pawing through people’s “life records,” and of a bureaucratic scheme to erase workers’ names and replace them with numbers. This rhetoric reached its crescendo on Halloween, fittingly enough, when John Hamilton, chairman of the Republican National Committee, stood before a crowd of twenty thousand in Boston, clutching a stainless-steel “specimen” tag stamped “Social Security Board”; Hamilton thrust it in the air and insisted that if F.D.R. were reëlected, tags just like it would be “hung around the necks of twenty-seven million” working men and women. The Roosevelt Administration, he asserted, had already sought bids for machines to manufacture the tags. (Hamilton refused to divulge where he’d gotten the sample, but after the rally, he let reporters pass it around and inspect it.)

And then Roosevelt won in a landslide. The payroll tax went into effect two months later, provoking no great outcry, either by the public or, at that point, the Republican Party. Implementation of the Social Security program, despite its unprecedented complexity, was mostly smooth and efficient. And in May, 1937, the Supreme Court—seen by conservatives as “the last thin line” between freedom and totalitarianism—upheld the Act (a surprise decision that I describe in “Supreme Power,” my book on Roosevelt’s Court-packing fight). Thus marked the wholesale defeat (a trifecta—rebuked by all three branches) of the G.O.P. on Social Security, and the beginning of the party’s return to what future Republicans would call the “reality-based community.” It was a slow, grudging, and partial return—the party then, as now, was ideologically riven—but it did signal the G.O.P.’s ability to recalibrate its rhetoric, cut its losses, and draw on its reservoir, however depleted, of common sense. The next dozen years brought a fair amount of sparring and foot-dragging on Capitol Hill anytime the Act required amendment or revision, but this was more a kind of harassment than a serious renewal of hostilities. Conservatives did not learn to love Social Security; they just learned to live with it.

This might bode well for the A.C.A., over the long term, if today’s brand of lunacy were more like that of the thirties—that is, in some measure trumped-up and tactical. It’s not that New Deal-era Republicans didn’t believe what they were saying about the end of liberty; many earnestly did. They hated Roosevelt, too, genuinely and irrationally. But when Hamilton held that dog tag in the air in 1936, he knew exactly what he was doing and why. His calculus was cold-eyed (if wrong-headed). He was inciting voters to take leave of their senses. Yet, for all the nuttiness of his presentation, he had not taken leave of his own.

Therein lies the difference between the Republican Party of the past century and the Republican Party of our own (especially, but not exclusively, its Tea Party faction): the difference between calculation and obsession, between a hysterical style and an honest-to-goodness, diagnosable hysteria—the collective kind, like the compulsive dancing manias of medieval Europe. “They have lost their minds,” said the Senate Majority Leader, Harry Reid, on Monday night—a comment that, on the evidence, seemed less a partisan attack than a simple, regrettable statement of fact.

Photograph by John Vachon/Library Of Congress/Getty.