Jilted.

As we enter the sixth year of the George W. Bush presidency, there has been refreshingly little discussion of his legacy. David Bruce, Harry Truman's under secretary of state, had perhaps the wisest approach: "I wouldn't try in my own mind ... to fix the place in history of any president until he had been dead for at least fifty years." Such advice is especially prudent in Bush's case; so much depends on things to come.

But as Bush's presidency winds down, it is inevitable that this discussion will begin. Perhaps the first volley in the battle over the Bush legacy has been launched in the form of Impostor, the new book by former Reagan Treasury official Bruce Bartlett. Bartlett is an unusual author for a book with such a title. He is well known and respected in the Washington conservative policy community. He is erudite and collegial, and well liked for his quiet sense of humor and pleasant manner. His syndicated column appears on National Review Online.

Yet the title and the tone of this anti-Bush jeremiad suggest that Bartlett has lost his temper. He writes about Bush like a jilted lover. In Bush's approach to policy, for example, Bartlett observes "an apparent disdain for serious thought." Cynics will accuse Bartlett of trying to cash in on the anti-Bush rage that has generated massive book sales for other authors; but I know Bartlett, and I'm sure that the strong feelings revealed in his biting language are quite genuine.

How angry is he? Bartlett is so angry that he dedicates a whole chapter to a comparison between Bush and Nixon, someone, he writes, who is viewed as "one of the worst presidents in American history." Bartlett clearly thinks Bush is headed down the same path: "Bush could end up having the same negative effects on himself and the economy as Nixon brought on."

What has set him off is a long list of Bush's apparent crimes against economics and the Reagan legacy. The list is not fanciful: Government spending has surged under Bush. The prescriptiondrug plan is one of the biggest expansions of entitlements on record. The Sarbanes-Oxley bill did create massive and costly new regulations. Bush's trade record, from textiles to steel, is at times quite unattractive. In Bartlett's opinion, even the vaunted tax cuts squandered revenue on such things as the Child Tax Credit and the tax rebates--which have little economic consequence--rather than on marginal-tax-rate reductions, which would have done much more to promote growth.

The big question is: Why did Bush propose these policies while claiming to be an heir to the Reagan legacy? Bartlett's portrait of the Bush White House suggests that Bush is all about politics and power. He is a rube who lets the political shop run his economic policy; he makes bad economic policy and then attacks economic staffers if they complain. He moved the economists across town, and doesn't listen to them. Morale among economists is so low that nobody wants to work in the administration any longer.

But it is perilous to draw conclusions about internal affairs and other people's motives based on limited information. My own sense from discussing the book with current and former administration officials is that Bartlett's characterization is unfair and incorrect. One former senior official told me that Bush pores over his briefing books with such focus and acuity that he catches staffers when they say things that disagree with information from previous briefings. Another former senior economic official told me that Bush demands frank and accurate discussion of economic issues from his staff. My own experience with Bush is more in line with that of these former staffers: When discussing economics, he seems very well informed, and comfortable with complexities.

Indeed, a Bush supporter might respond that the real problem is that, in our system, the president is too weak to have a strong influence on economic policy. Bush clearly wanted to reform Social Security; Congress wouldn't bite. He assembled a tax panel that designed a code that is much better than our current one, better than Reagan's 1986 tax reform; his political team, probably accurately, determined that the plan would never make it through Congress. Who should bear the blame, Bush or Congress?

True, conservative nirvana has not been reached during the Bush years. But prescription-drug benefits and Sarbanes-Oxley, Bush might argue, were going to happen anyway, and by enacting them on his own watch he made the best of a bad hand. A president is not a king.

Such arguments can go only so far, however, which is one reason Bartlett's book will ignite a lively debate. Government spending has been out of control on Bush's watch, and he has failed to veto a single bill even as the pork spending keeps on rolling. That is troubling, and maybe even a serious flaw, but Bartlett fails to make his case that Bush is comparable to Nixon.

Economics may be Bartlett's primary concern, but it will not be history's, and it has not been Bush's. The Bush legacy will be inescapably bound to the Middle East. His bold gambits in Afghanistan and Iraq may prove successful, in which case it is hard to imagine history's neutral voices frowning upon the man. History loves courage and conviction. But if terrorism and holy wars fill this century, Bush's failure will be viewed as a crucial and terrible turning point. Courage is not enough if one's convictions are wrong.

Given these stakes, it is hard to imagine economics influencing the historians' assessments significantly. The economy has been quite strong in recent years, humming along oblivious to the cries of the twin-deficit-obsessed doomsayers. Bush's spending policies may have helped him maintain political support for the War on Terror. His tax policies have contributed to the good economic news, perhaps offsetting the damage from bigger government. Who knows, a peace dividend may even help bring government back to a reasonable scale sometime soon.

One can bet that Bush has adopted the stances that he has, not because he is an impostor, but because he believes, as Harry Truman did, that time is on his side. "To hell with them," Truman once said, "When history is written they will be the sons of bitches--not I."

Mr. Hassett is a resident scholar and director of economic-policy studies at the American Enterprise Institute.