Politicians who try to legislate fairness are kind of like families that try to keep themselves warm at night with one small blanket. No matter how they go about it, someone gets left in the cold.

Lamar Alexander came by the office a few days ago. Now, I don't need to peer through the newspaper to know that most of you are shaking your heads, squinting your eyes and muttering, "who?" Political name recognition has a short shelf-life.Alexander, the former governor of Tennessee, was a Republican presidential candidate in 1996. He was the one who always wore red plaid shirts and who published a quaint book of homilies (an example, from Page 38: "If it was a mistake and you did it, admit it and try not to do it again").

Obviously, he didn't think his candidacy was a mistake. He's running again in 2000, and stranger things could happen than a shell-shocked, morally outraged nation electing someone like Alexander. People have come out of nowhere before following a scandal. Remember Jimmy Carter?

Now that the growing tentacles of Clinton-Lewinsky seem to be reaching farther each day, to the point where GOP hopeful George W. Bush has said he may not run, the idea of a serious candidacy from the squeaky-clean, home-spun Alexander may not be too far-fetched. In that case, it's time to set everyone straight on one point.

Alexander has appeared on television commercials in recent weeks attacking the so-called "marriage penalty" in the tax code. The ads in Utah are part of a nationwide blitz sponsored by his new political action committee called "We the Parents."

This all plays into his greater platform of family-friendly issues. It's designed to resonate with Americans who believe in traditional marriages, families and values. My guess is the only thing a politician would more readily jump behind would be the abolition of a tax that penalized mothers or apple pie.

But while it's easy to attack something labeled a "marriage penalty," particularly in a state like this one where marriage is taken seriously, it's much more difficult to define what the term means and to come up with something more fair.

We ought to know by now that any time politicians try to patch something perceived as hurting a group of people, the safe bet is they're merely passing the hurt onto someone else. The truth is that eliminating the marriage penalty would, in many cases, penalize families who decide Mom should stay home with the children.

Here's how the tax code works. If, for example, a man and a woman each earns $24,650 a year and they remain single, they would pay 15 percent less in taxes than if they decided to get married. Alexander and others call this a financial incentive for people to live together out of wedlock.

But like the proverb of the blind men examining an elephant, the tax code looks different depending on which end you examine. Consider this scenario: If one of the partners works and the other doesn't, the earner actually ends up paying less in taxes once the wedding bells chime. That would be better described as a "marriage bonus," a term you're not likely to hear much this fall.

Any plan that reverses this system would hurt traditional families with stay-at-home moms. A home where each partner earns $25,000 per year would pay less in taxes than a home where only the father works and earns $50,000, even though the household income is the same in both cases. Is that what we want?

To his credit, Alexander acknowledged this weakness when I confronted him with it. But he said the change is necessary because the current system discriminates too much against working women. He would counter the disadvantage to stay-at-home moms by pushing an $8,000 tax deduction for each child, more than triple the current $2,700 rate.

Does all of this seem complicated? That's because it is, which may be the Alexander plan's biggest weakness. His main GOP opponents are talking about scrapping the current tax system all together and replacing it with something simpler. Alexander is trying to make the current system more fair, which is the equivalent of trying to level off a table by adding different size books under each of the legs.

Alexander's heart may be in the right place, but a plan that forces people to decide whether they'd rather encourage marriage or encourage mothers to stay home isn't likely to resonate with the public. My guess is most of them would rather weave a better blanket than try to make the old one keep everyone warm.