By all means, national debates over taxes should be driven only by revenue needs and considerations of fairness, not by partisan politics.

So President Bush is to be commended for calling in his State of the Union address for a bipartisan commission to study the impact of a cut in the capital gains tax.But don't count on the proposal's generating more light than heat.

Just the mention of a possible cut in the tax on capital gains gives its critics an excuse to revive old canards about both the plan and the rich. More specifically, it gives congressional Democrats a fresh excuse to accuse Republicans of being the party of the rich and it breathes new life into misguided efforts to impose a surtax on millionaires.

Remember what happened last year when the White House pushed for a lower tax on profits from the sale of property? The objective was to stimulate the economy by encouraging investment. But the issue divided Congress so deeply that the proposal finally was eliminated from budget discussions.

The main arguments against the proposed cut were that fully 85 percent of the tax benefit would go to the rich, who were accused of getting a free ride in the past decade and not paying their fair share.

Those claims, however, were so far off base that it shouldn't take a special bipartisan study commission to expose their folly.

For openers, tax rates did indeed fall during the 1980s, including rates for the rich. But that caused the rich to pay more, not less, in taxes by reducing incentives to shield incomes. In 1981, Scripps Howard News Service reports, the top 1 percent of taxpayers paid 17.9 percent of all income taxes. Now, after the rate cuts of the 1980s, the top 1 percent pays 25 percent of all income taxes.

What's more, the Tax Foundation in Washington, D.C., estimates that if Washington confiscated the entire incomes of all Americans earning $200,000 a year or more, the revenue raised would run the government for only 41 days.

What about the estimate that 85 percent of the benefit from a lower tax on capital gains would go to the rich? Wrong again!

Most capital gains are one-time deals. But if a couple earns $50,000 and sells their house for a $50,000 profit, the phony 85 percent estimate counts them as a $100,000-income couple even though next year and the year after they will earn only $50,000.

When judged on actual wage income, fully half the benefits of a capital gains tax cut would go to people who earn $50,000 or less. These are not the rich.

Finally, take a closer look at how the benefits from a lower capital gains tax should be calculated. If the tax cut puts more money in a person's pocket, he or she is likely to re-invest some or all of it. With such new investment capital, a company can provide new jobs for new workers. Why, then, count just the investor as the only beneficiary of the tax cut? What about the workers who got new jobs?

Such economics are so basic that it really should not take a special study commission to determine the impact of a cut in the tax on capital gains. But some people find it easier to seek scapegoats than solutions. How many politicians, then, are going to let the facts stand in the way of their beating up on the rich even though the mayhem isn't justified?