People remember embarrassing phrases from the last Bush campaign: The promise to be "a uniter, not a divider," which presaged the most polarizing presidency of recent times; the promise to conduct a "humble" foreign policy. But if you read George W. Bush's convention speech of four years ago, it's amazing how honestly it heralds the hair-raising radicalism that followed. It's full of macho lines about bold action and seizing the moment and appointments with greatness. And the central rhetorical device in the first part of the speech is a refrain:

"This administration had its moment; they had their chance; they have not led. We will," Bush declared repeatedly.

He wasn't kidding. Even before Sept. 11, 2001, Bush signaled his future impatience with Europe's diplomats by tearing up both the Kyoto environment treaty and the Anti-Ballistic Missile Treaty. He delivered the most radical tax cut since 1981 and transformed federal education policy, and the early signs were that he really meant to privatize Social Security. It isn't true, as some now suppose, that Bush's radicalism is merely the product of 9/11 -- that extraordinary times drove an otherwise temperate man to extraordinary measures. Bush behaved extraordinarily in ordinary times too. As he promised in his convention speech four years ago, "We will write not footnotes but chapters in the American story."

Part of me quite likes this. There's plenty of stuff that's wrong with the world, and presidents ought to be activists. Bush's radicalism -- his willingness to see problems and embrace bold solutions despite urgings of caution from all sides -- can be glorious when applied to a good cause: Think of his huge expansion of international AIDS funding, which goes way beyond anything the Clinton administration ever contemplated. But Bush's radicalism has a scary side as well, and it goes to the heart of his fitness for a second term. In his zeal to be a strong leader, and in his disdain for policy detail, Bush sometimes defends positions that have no intellectual basis.

This weakness is most commonly associated with his war in Iraq -- a radical policy that has backfired on him. Even if you accept the case for war, the way Bush has argued it raises fundamental character issues. Why did he claim links between al Qaeda and Saddam Hussein despite the lack of evidence? Had he failed to absorb the facts, or was he being plain dishonest? Why did he allow the postwar planning to be so scandalously poor? Could he not be bothered to cross-examine the officials who were drawing up plans that would determine his standing in history? Bush appears to have been deaf to the chorus of outside experts who warned that nation-building would be difficult. Doesn't this illustrate a lazy lack of curiosity about how bold ideas will play out in the real world? Doesn't this raise doubts about Bush's fitness to be president?

The same goes, until a few days ago at least, for the more recent handling of the Iraq question. Bush has been so caught up on his strong-leader kick that he has found it difficult to pause, adjust his policies and admit error -- even when error became obvious. Confronted with the prisoner abuse scandal, he has sought to scapegoat a few junior officials and move on rather than admit that his lawyers' dismissal of the usual rules of war has been proved disastrous. Confronted with the absence of weapons of mass destruction, Bush has failed to acknowledge a mistake -- even though he could explain at the same time that statesmen make decisions on the basis of imperfect information and that the best information was that Iraq had such weapons. This sort of honest but subtle argument is alien to the strong leader's style. As Bush reportedly once said, "I don't do nuance."

The clearest illustration of this inflexibility is not Iraq. It is the central plank of the economic agenda: the tax cuts. These were conceived when the economy was booming and huge budget surpluses were expected, but when the boom turned into bust, Bush showed no ability to course-correct. Almost unbelievably, Bush not only rammed through the huge tax cut he had promised in the campaign: He cut taxes again in 2002 and a third time in 2003. Even now he seems ready to sign an appalling pork-ridden corporate tax reduction. In the past, ambitious tax cuts have tended to happen only once every two decades or so. Before Reagan's in 1981, you have to go back to 1964 to find anything comparable. Bush's tax radicalism is breathtaking.

Again, this is not just a policy issue; it goes to Bush's character. How can he push such a dramatic shift in economic policy without grappling with the basic point that his cuts are unaffordable? He chants that he will halve the deficit within five years, but this is beside the point: The cost of the tax cuts falls mainly beyond the five-year window, as does the cost of the baby-boomers' retirement. Perhaps Bush fails to understand that his policies are unsustainable, or perhaps he understands but refuses to say so. In other words he is either ignorant or dishonest: Neither suggests that he deserves the trust of the electorate.

There is still time for Bush to level with voters. Last week he ventured to the New York Times that there were miscalculations in Iraq, and the extent to which he builds on that admission must be a central test of his candidacy. In the run-up to this week's convention, some people have suggested that Bush needs to spell out a governing agenda for a second term -- that more ideas are needed. But the truth is that Bush has no shortage of radical ideas. The question about his candidacy is whether he has other qualities: A willingness to grapple with the messy reality of the world and the honesty to switch course when necessary -- in a word, pragmatism.