FUZZY MATH: The Essential Guide to the Bush Tax Plan.

FUZZY MATH: The Essential Guide to the Bush Tax Plan by Paul Krugman W.W. Norton & Company, $17.00

THE MORNING AFTER A SUPINE Congress passed the Bush tax-cut bill, Paul Krugman took refuge in the greatest privilege of a newspaper columnist--the immediate ability to fulminate, to fume, to foam, to froth, to fret, and to work oneself into a frenzy in print. Until the final legislation took shape, Krugman declared in his New York Times column, "I thought that the fraudulence of the tax plan would take a few months to become totally obvious. But I underestimated the smirking contempt of the tax cutters for the public's intelligence."

Krugman, in his rightful contempt for this "abomination," made another small miscalculation. Less than two weeks before the bill was rushed to President George W. Bush for his triumphant signature (the president dropped his pen during the ceremony), Krugman published a 128-page screed against the tax bill. Talk about a book with the shelf life of fresh-caught scrod. But there is no need for this slim volume to become pulped non-fiction. The columnist-economist (as strange a hyphenated professional existence as, say, an actress-botanist) is such an artful explainer that it doesn't really matter that this book is already past its pull date. For what Krugman really offers is a toxic-waste-dump tour of the dubious premises that contaminate all Bush-era economic thinking, from the administration's deliberately parsimonious budget to the continuing shell games over the Social Security and Medicare trust funds.

Even as a devoted student of the fiscal analyses by the Center on Budget and Policy Priorities and Citizens for Tax Justice, I found Krugman's book brimming with statistics and arguments that I had not read elsewhere. To cite one telling example, which refutes conservative claims that rapacious federal bureaucrats are draining the Treasury dry, non-defense discretionary spending has, since 1986, grown at a slower rate than the economy as a whole. What we regard as the government--the Education Department, the Environmental Protection Agency and the Immigration and Naturalization Service--has been under-funded for 15 years. As Krugman puts it, "If you think that we suffer from a severe case of big government you should be aware that even civilian discretionary spending is lower today as a share of the economy than it has been since Dwight Eisenhower--yes, Eisenhower--was president."

In outlining his philosophical and practical objections to the tax bill itself, Krugman gives the greatest weight to the argument that the funds simply will not be there to pay for it. This is the fiscal-responsibility case that the congressional Democrats largely abandoned as soon as the Congressional Budget Office (CBO) computers projected a magic $5.6 trillion surplus over the next 10 years. Instead, most Democratic oratory, echoing the mock populism of Al Gore's presidential campaign, zeroed in on the unfairness of the tax-relief windfall awaiting the upper 1 percent. But such inept class warfare obscured the fallacies inherent in the CBO's 10-year budget estimates. For Krugman points out that just because the CBO projections are non-political doesn't make them accurate. There is a major bias in the CBO's idiot-savant assumption that all discretionary federal spending will remain unchanged for the next decade, aside from inflation adjustments. "The U.S. population is expected to grow about 10 percent over the next decade," Krugman writes, "so the CBO's projection assumes a 10-percent decline in real per capita spending" A more reasonable analysis, pegging discretionary federal spending to the anticipated growth in what economists call the Gross Domestic Product, would trim $600 billion off the surplus estimates.

Sometimes Krugman, who freely admits, "I have no particular expertise in political analysis," goes a bit over the top in his rhetorical zeal, such as when he claims that "conservatives would like to see Lyndon Johnson's Great Society and maybe even Franklin Roosevelt's New Deal rolled back." Not exactly. What Krugman misses is the way that Bush's smiley-faced compassionate conservatism differs from Newt Gingrich's down-with-government jeremiads. The Bush budget doesn't try to eliminate such easy right-wing targets as the National Endowment for the Arts and Amtrak subsidies. Instead, Bush, unlike Ronald Reagan, has made his peace with existing governmental programs. The president's conservative agenda is built around placing such a fiscal straitjacket on the federal government that Congress will not able to create new initiatives or entitlements.

Krugman, in his introduction, explains that "this book offers me an opportunity for a longer form of discussion that can't be squeezed into 735-word columns in The New York Times." Yes, for all its soap-box-derby freedoms, the constricted length of a newspaper column does indeed militate against complex analysis. Now that he has got the hang of the column-writing dodge, Krugman probably felt that the 128-page heft of Fuzzy Math made it an epic saga on par with War and Peace. But for the rest of us, this valuable guide to how we were all bushwhacked on taxes is more akin to an old Kurt Vonnegut volume called Welcome to the Monkey House.

WALTER SHAPIRO is a political columnist for USA Today and a contributing editor of The Washington Monthly.