In the nineteen-eighties, when the Democrats had perfected the practice of blowing Presidential elections, The New Republic used to run what it called its “Quadrennial Recriminations Issue.” The 1988 cover illustration, by the cartoonist Mark Alan Stamaty, portrayed party notables kicking, biting, and bludgeoning their way toward mutual misunderstanding. Imagine this same scene rendered by Hieronymus Bosch, and you’d have a pretty good depiction of the next meeting of the House Republican Conference.

Indeed, few are taking Harry Reid up on his plea, guileful though it no doubt was, to make this “a time of reconciliation.” The air on the right is thick with reproach: even before the final vote had been taken, John McCain launched the first “I told you so,” while Ted Cruz, remorseless to the last, scolded “the Washington establishment” for “failing to listen to the American people”—presumably, the few American people who agree with Ted Cruz. The Republican Party, from the rank and file right to the top, is engaged in one of those bench-clearing brawls we see from time to time in baseball, except all the brawlers are on the same team.

It is chaos, but that is not stopping commentators from finding order in it. There is talk everywhere of a Republican “civil war,” of a “schism,” of the G.O.P. as “a coalition of two parties” that can no longer stand the sight of one another. All of this assumes clear lines of division—sharply contrasting enemy camps. The Tea Party contingent, for its part, seems well enough defined. It has, after all, its own House caucus. (Of course, beef, boating, and bourbon each have their own House caucus, as do Albanian issues and contaminated drywall, but some caucuses are more equal than others.) These are the intransigents, the principled insurgents; the Senate leadership, their foil, is cast as the establishment—the Chamberlains to Cruz’s self-styled Churchill. Yet there’s not a dime’s worth of ideological difference between the two sides.

As Jonathan Chait and others have argued, there are real, honest-to-goodness distinctions to be drawn between Tea Party Republicans and the G.O.P. establishment, but they boil down, almost entirely, to tone and tactics. On the big questions, the G.O.P. remains a very small tent. Consider this tale of the tape by FoxNews.com, breaking down the issues said to be dividing the party. On the debt, “Tea Partiers want to balance the budget [and] end runaway government spending.” Don’t mainstream Republicans want that, too? “Republicans aren’t opposed to those demands,” Fox concedes, but wonders whether they really mean it. On the size of the federal government, the Tea Party would prefer theirs smaller, please. Mainstream Republicans? Yes, them, too. On tax cuts, “Tea Partiers and mainstream Republicans agree.” On Obamacare, “Tea Partiers want to defund, repeal and replace the law,” while mainstream Republicans, Fox reports, “have echoed similar sentiments.” At this point, the G.O.P. civil war is sounding less substantive, and certainly less dangerous, than the East Coast–West Coast hip-hop feud of the nineteen-nineties.

A more ambitious, but equally fruitless, attempt at ideological hair-splitting was made in a recent post by Ross Douthat, of the New York Times, who does his best to discern “a policy struggle” amid the pandemonium. Douthat finds one: a sub rosa, “inchoate” dispute over which provisions of the Affordable Care Act to delay, and to what extent the middle class should share in the benefits of any tax-reform deal. These are indeed differences, in the literal sense of the word. And it is true that Republicans disagree, sometimes hotly, over issues like immigration and foreign aid. But, of course, Democrats disagree, sometimes hotly, over issues like free trade and the Keystone XL Pipeline. The parties are not, and have never been, monoliths.

In 1912, Theodore Roosevelt stormed out of the Republican Convention, thundering about Armageddon, and ran for President on the Bull Moose ticket—driving a wedge between Republican progressives and conservatives that remained there, at the heart of the G.O.P., for more than a generation. The Democratic Party, too, was chronically and substantially divided. In 1938, Franklin Roosevelt tried to purge its conservative elements and force a wholesale partisan realignment; by intervening (clumsily, and mostly unsuccessfully) in that year’s Democratic primaries, he helped turn a rift into a permanent split. It presaged the serious, philosophical divide between “entitlement liberalism” and “opportunity liberalism” in the wake of the Great Society, as well as the competing worldviews of hawkish, Scoop Jackson Democrats and the dovish supporters of Eugene McCarthy and George McGovern.

But none of these intraparty struggles can match, in terms of sheer bile, the battle between so-called Rockefeller Republicans and Goldwaterites over the 1964 Presidential nomination and, more significantly, the soul of the G.O.P. What the party’s dominant, liberal, eastern wing—and its standard-bearer, New York Governor Nelson Rockefeller—proposed was not to end the welfare state but, in effect, to manage it better. To the extent that Rockefeller had a critique of the Great Society, it was that the poverty program was underfunded. (Rockefeller later said that the War on Poverty was “most imaginative and constructive.”) To Senator Barry Goldwater, the leadership of the Republican Party was no less guilty than the Democrats of the high crimes of “liberalism, welfarism, and paternalism.”

And with that, the party commenced to eat itself alive: Rockefeller forces vowed to expel the extremists from the G.O.P. and, as a Rockefeller adviser put it, “destroy Barry Goldwater as a member of the human race”; Goldwater’s supporters heralded (correctly, it turned out) the end of what the columnist Russell Kirk called “the long era of ‘me-too’ Republicanism.” At the Republican Convention in July of 1964, ugly, public battles ensued over the civil-rights plank; Rockefeller spoke of moderation and was booed; television reporters were shoved around; Goldwater delegates put out their cigarettes on the suit of an elderly black Republican; and the nominee himself, famously, put in a good word for extremism. As well he might have: it had won in a blowout.

The extremism of our own age—Tea Party extremism—“contaminates the whole Republican brand,” as David Frum has written. And he’s right. But Tea Party extremism is not, as this implies, a betrayal of the party’s belief system. It is, instead, a crystallization, a highly potent concentrate, of the party’s belief system. The free-market dogmatism, the tax-cut catechism, the abhorrence of nuance and science and government and fact—these did not bubble up during town-hall meetings in 2010 but flow from the same deep well from which establishment Republicans like Mitch McConnell (Goldwaterites, all) have long been drinking. Frum and other sensible conservatives yearn for a Tea Party exit—maybe even an expulsion—from the G.O.P. But it cannot be expelled, because in this case the parasite is a creation—in some ways a perfection—of the host organism itself.

Jeff Shesol, a former speechwriter for President Clinton, is the author of “Supreme Power: Franklin Roosevelt vs. The Supreme Court” and is a partner at West Wing Writers. Follow him on Twitter at @JeffShesol.

Photograph by Julian Wasser/Time Life Pictures/Getty.