Ideologie has taken over.

With 9/11, George W. Bush was reborn (again). Until then, his presidency had been undistinguished and his poll numbers low. He had also made one particularly ominous decision. In August 2001, using an executive order, Bush blocked federal support for stem-cell research. In substance that was bad enough--like many people I oppose disease and early death--but equally disturbing was the mindset. Bush summed it up in 2004, when he described stem-cell research as a project "to destroy life to save life."

Wait a minute. Here Bush was using the same word, "life," to describe not only a minute clump of cells known as a blastocyst but also an actual human being. In this flagrant disconnect between words and actuality were the early indications of a profoundly ideological mindset.

Edmund Burke was the original enemy of ideology. In the slogans of the French philosophes, Burke saw something new and alarming in politics, and he struggled for language to describe it, writing of "abstract theory" and "metaphysical dogma." Burke was seeking a way to describe a belief system impervious to fact or experience, and he brought to bear a permanently valid analysis of human behavior and the role of social institutions. William F. Buckley once summed up Burke's outlook when he called conservatism the "politics of reality."

But that was then. Today, the standard-bearer of "conservatism" in the United States is George W. Bush, a man who has taken the positions of an unshakable ideologue: on supply-side economics, on privatization, on Social Security, on the Terri Schiavo case, and, most disastrously, on Iraq. Never before has a United States president consistently adhered to beliefs so disconnected from actuality.

Bush's party has followed him on this course. It has approved Bush's prescription-drug plan, an incomprehensible and ruinously expensive piece of legislation. It has steadfastly backed the war in Iraq, even though the notion of nation-building was once anathema to the GOP. And it has helped run up federal indebtedness to unprecedented heights, leaving China to finance the debt.

Perhaps most damaging to the ideal of conservatism has been the influence of religious ideology. During the fight over whether to remove the feeding tube of Terri Schiavo, a Florida woman who had been in a vegetal state for 15 years, politicians began to say strange and feverish things. "She talks and she laughs, and she expresses happiness and discomfort," Majority whip Tom DeLay said of a woman for whom cognition of any kind was impossible. (Oxygen deprivation had liquefied her cerebral cortex.) Senate Majority leader Bill Frist examined Schiavo on videotape and deemed her "clearly responsive." As Schiavo's case fought its way through the courts, Republicans savaged judges for consistently sanctioning the removal of Schiavo's feeding tube. "The time will come for the men responsible for this to answer for their behavior," threatened DeLay.

That members of the judiciary were being chastised for responding to the law as written rather than looking, presumably, to some sort of divine guidance was hardly surprising. In 2002, Bush himself had said, "We need commonsense judges who understand that our rights were derived from God." In this chilling use of the word "God," the president made his views on the rule of law all too clear. The conservative writer Andrew Sullivan has aptly coined the term "Christianism" to refer to this merger of religiosity and politics.

As Bush's ideology leads from one disaster to another, one might ask: How far can it go? It has already brought us to Baghdad, an adventure so hopeless that Buckley recently mused, "If you had a European prime minister who experienced what we've experienced, it would be expected that he would retire or resign." The more we learn about what happened behind the scenes in the months leading up to the war in Iraq, the more apparent it becomes that evidence was twisted to fit preconceived notions. Those who produced evidence undermining the case for war were ignored or even punished. It was zealotry at its most calamitous.

On the subject of democratizing Iraq and the Middle East, Bush has voiced some of the most extraordinarily ideological statements ever made by a sitting president. "Human cultures can be vastly different," Bush told an audience at the American Enterprise Institute in February 2003, shortly before the invasion of Iraq. "Yet the human heart desires the same good things, everywhere on earth ... For these fundamental reasons, freedom and democracy will always and everywhere have greater appeal than the slogans of hatred and the tactics of terror."

Happy thoughts, breathtakingly false. If this amounts to a worldview, it's certainly not that of Burke. Indeed, Bush would probably be more at home among the revolutionary French, provided his taxes remained low, than among Burke's Rockingham Whigs. (Burke would of course deny Bush admission to the Whigs in the first place, as Bush would be seen as an ideological comrade of the philosophes--if a singularly unreflective one.) It's no surprise that longtime conservatives such as Francis Fukuyama, George F. Will, and William F. Buckley have all distanced themselves from Bush's brand of adventurism.

The United States has seen political swings and produced its share of extremists, but its political character, whether liberals or conservatives have been in charge, has always remained fimdamentally Burkean. The Constitution itself is a Burkean document, one that slows down decisions to allow for "deliberate sense" and checks and balances. President Bush has nearly upended that tradition, abandoning traditional realism in favor of a warped and incoherent brand of idealism. (No wonder Bush supporter Fred Barnes has praised him as a radical.) At this dangerous point in history, we must depend on the decisions of an astonishingly feckless chief executive: an empty vessel filled with equal parts Rove and Rousseau.

Successful government by either Democrats or Republicans has always been, above all, realistic. FDR, Eisenhower, and Reagan were all reelected by landslides and rank as great presidents who responded to the world as it is, not the world as they would have it. But ideological government deserves rejection, whatever its party affiliation. This November, the Republicans stand to face a tsunami of rejection. They've earned it.

Meanwhile, as we wait out our time with this president, we can look forward to the latest in a stream of rhetoric that increasingly makes Woodrow Wilson look like Machiavelli. "One, I believe there's an Almighty," Bush declared this April, "and secondly I believe one of the great gifts of the Almighty is the desire in everybody's soul, regardless of what you look like or where you live to be free. I believe liberty is universal."

Well, it is certainly taking a long time for the plans of the Almighty to show results in the actual world. As I write this, sectarian violence in Iraq is escalating. I'd call my skepticism "conservative," but Bushism has poisoned the very word.

Jeffrey Hart, professor of English emeritus at Dartmouth College and senior editor at National Review, was a speechwriter for Richard Nixon and Ronald Reagan. He is the author, most recently, of The Making of the American Conservative Mind: National Review and Its Times.