But by the early 1960s, Buckley’s most intellectually formidable colleagues (Chambers and the political theorist James Burnham) had prevailed on him to make the magazine more politically responsible. At the same time, Welch was moving in the opposite direction, founding the John Birch Society in 1958 to promote the view that Soviet spies had penetrated the highest levels of the United States government. Over the coming years, Welch and his organization would accuse a long list of public figures of acting as Communist agents, including Eisenhower himself, Eisenhower’s secretary of state John Foster Dulles, and the young Henry Kissinger. The Birch Society also launched a campaign to impeach Chief Justice Earl Warren for using the Supreme Court to prepare the way for a Communist takeover of the country.

In April 1961, Buckley wrote the first of several editorials blasting Welch for spreading conspiracy theories that were both implausible on their face and likely to do considerable political harm to the conservative cause they both professed to believe in. Hundreds of angry letters streamed into the offices of the magazine, subscriptions were canceled, prominent donors withdrew their support, and the magazine’s staff split into polarized factions. To his considerable credit, Buckley kept up the assault on Welch and the Birchers, ultimately establishing that the conservative movement would not tolerate conspiratorial forms of argument.

Buckley responded similarly to George Wallace during his third-party presidential run in 1968. Making a play for many of the voters who had cast ballots for Goldwater four years earlier, Wallace portrayed himself as more conservative than the Republican nominee, Richard Nixon. Buckley disagreed, calling Wallace a “dangerous man” and a “welfare populist” who stoked anger and resentment among blue-collar voters and favored increased federal spending, provided it went only to whites and did nothing to further civil rights for African-Americans.

In his final act of excommunication, Buckley took a stand against the paleoconservative Pat Buchanan in 1991 for expressing opposition to the Persian Gulf war in terms that were both incendiary and undeniably anti-Semitic. (Buchanan had claimed that the only two groups clamoring for war were “the Israeli Defense Ministry and its amen corner in the United States” and described Congress as “Israeli-occupied territory.”) Later that year, Buckley sought to expose and root out remaining vestiges of anti-Semitism on the right in a lengthy essay that filled an entire issue of National Review.

Those were the factions of the right that Buckley aimed to exclude from the conservative movement: proudly plutocratic libertarians; conspiracy theorists; angry, race-baiting populists; and paleocons dabbling in ethnic demonization.

Sound familiar?

If it was once possible for members of the conservative movement to tell themselves that these factions had been driven into the political wilderness for good, recent events tell a more disconcerting story. Even when one side of a political argument appears to prevail decisively, it rarely succeeds in vanquishing the losers, who often live on to fight another day, sometimes years or decades later, more powerful and politically formidable than ever before.