As the republic lurches into the last year of the Constitution's second century, the intersection of two bills "in Congress has cast a stark white light on the condition of representative government.

The tax bill cobbled together by Rep. Dan "The Refrigerator" Rostenkowski is a product of government at its most conventional. And the Gramm-Rudman-Hollings deficit eraser is a rare example of radicalism. As radicalism usually does, it gives prudent people a fresh appreciation of the virtues of the conventional.

Rostenkowski comes from Chicago's west side -- Bears country -- where politics is as the coach described football: "Is football a contact sport? No, dancing is a contact sport. Football is a collision sport."

As this is written, the fate of the tax bill is in doubt -- as is the truth of the proposition that its fate matters much. If the bill dies, that will be because so many House Republicans (the only Republicans in Washington who are downtrodden) have vented their institutional resentment as well as economic doubt about the bill. They have suffered too many collisions with House barons like Rostenkowski.

The bill can be characterized with reference to three provisions.

This nation allocates too much savings (capital) to housing, in part because of the deductibility of mortgage-interest payments. The "reform" bill does not even limit deductibility, even for second homes. Aspen and Sun Valley, the construction industry, construction workers and various other interests say: "Thanks, 'Fridge.'

His Ways and Means Committee turned a baleful eye on the plutocratic practice of treating the purchase of sports tickets as a deductible business-entertainment expense. The committee was stern, saying: Take clients to the box seats but no more deductions for . . . luxury skyboxes. Call that populism.

And speaking of the defense of the little guy (which in Washington means the little interest group), consider the gravestone industry. Its special depletion provision for granite quarries has survived the great crusade for "simplification." Georgia is pleased. And Pennsylvania, where many tuxedos are made, is pleased about the more generous depreciation allowance for rental tuxedos.

Clearly this bill is less than root-and-branch reform. Politicians adore this axiom: The perfect is the enemy of the good. Meaning: If you hold out for excellence, you will not even get adequacy.

But it is hard to see why Republicans do not consider Rostenkowski's bill even adequate. There are important differences between what Reagan sought and Rostenkowski wrought, but Rostenkowski's bill does what Reagan wants, in broad outline. It cuts personal and corporate tax rates and pays for the cuts by making less generous the tax treatment of business investment.

True, Rostenkowski's bill overdoes the latter because it rejects Reagan's idea of paying for lower rates in part by ending deductibility of state and local taxes. So the bill spurs personal consumption and burdens capital formation. That is not what the doctor ordered for a nation in which, according to first figures, third-quarter savings were a paltry 2.7 percent of disposable income. That is the lowest rate since the third quarter of 1950, when the Korean war and memories of wartime rationing had Americans buying everything not nailed down.

But at least this tax bill faces the fact that rate cuts have to be paid for. This is an improvement on the 1981 idea of self-financing cuts that pay for themselves through their stimulative effects.

Capital-intensive companies oppose the bill; many service and high-technology companies love it. We shall hear no more about "the" business "community." The business sector is riven by rival interests and the fight over the tax bill has extinguished communitarian feeling.

Some serious economists think the bill could trigger a recession by smothering capital spending. No one knows, especially in light of the fact that tax uncertainty is compounded by the Gramm-Rudman-Hollings leap-in- the-dark, the most irresponsible congressional action in living memory.

By protecting so much domestic spending (Social Security, many income maintenance and health programs), it has become a mechanism for attacking defense. When in the next few years the president proposes reaching the deficit target by cutting domestic spending, and Congress refuses to go along and also refuses to write its own menu of pains, the president will face a choice that will define contemporary conservatism: What does he value more, enhancement of U.S. security or avoidance of a tax increase?

Gramm-Rudman-Hollings has set a record. Never have so many legislators voted so apprehensively, knowing that they did not know what they were setting in motion. 'Tis the season to be jolly -- if you are made jolly by an unprecedented level of government-generated uncertainty.