IT IS OFTEN hard to decide whether Washington's ways are mad or bad or brilliant; and the latests twists in tax policy support all three descriptions. For much of this year, the congressional Republicans have been clamoring for a bad tax cut, which threatened to return America from its new and welcome state of fiscal health. Last week, however, Republicans switched course. They now shrug and say they are happy to do without the tax cut; they would rather save the money to pay down some of the $5.6 trillion debt. Since interest payments on that debt are a serious burden on the budget, the new Republican policy is brilliant.

Or rather, it is brilliant in its outcome; the process by which Congress arrived at this result fits into the "mad" category. Republicans originally backed the tax cut because they wanted to broadcast their empathy with voters' wallets and put President Clinton in the awkward position of vetoing their generosity. So they passed a flashy bill calling for $972 billion worth of cuts, rather than a more modest one that the president might actually have signed. It is this mad mixture of posturing and indifference to real policy that has produced the wise idea of debt reduction.

Optimists may see this as vindication for Washington's culture of gridlock. But the truth is not so comforting. For one thing, the Republicans may change their minds again and decide after all that a smaller tax cut might be in their interest. For another, though gridlock may be welcome on the tax issue, it is a curse on several others -- guns and soft money.

The budget itself illustrates the danger in gridlock. Although the advent of a surplus has generated talk of tax cuts, the truth is that the surplus will soon be wiped away by the inexorable forces of demography. Both Medicare and Social Security are projected to plunge into deficit as baby boomers age, and endless promises to fix both entitlement programs have yielded no progress. Again, Washington's culture of gridlock is the chief culprit. In most areas, it seems, mad is bad, not brilliant.