I wrote last month of a new study by Charles Murray in which he persuasively argued that differences in IQ -- in this instance, between siblings growing up under virtually identical familial and socioeconomic circumstances -- have a great deal to do with a person's eventual economic success in life.

More specifically, in studying 1,074 pairs of siblings in which one member was in the "normal" range of intelligence and in which the other member was in either a higher or lower quintile, the coauthor of The Bell Curve discovered results such as this:

For subjects in the top quintile, median earned income in 1992 was $33,500. It was $26,000 for those in the next quintile; $20,000 in the middle fifth; $14,000 in the fourth quintile; and $7,500 in the bottom category.

Murray found similarly stark connections between IQ and educational achievement, and he also showed how intelligence plays itself out in less direct, more circuitous ways.

For example, he documented how cognitively bright individuals tend to marry other cognitively bright individuals. A main result of this is that people with relatively high incomes tend to have spouses who also earn relatively high incomes. Which leads to large proportions of people with high IQs, in effect, growing "considerably richer" thanks to marriage, while less bright men and women wind up doing no better than growing "somewhat less poor" by getting married.

Fully taking into account that few topics are as combustible as IQ (never mind its racial aspects), and that few scholars are as radioactive as my friend Charles Murray, let me simply ask: What if he is right?

What if, in the "information age" economy, native intelligence really has come to play a larger part than ever before in determining economic winners and losers? Beyond matters of justice and fairness, what implications, for example, might such a development have in the perpetual competition between liberals and conservatives, Democrats and Republicans, when it comes to winning the hearts and minds of voters? To questions like this, Murray himself writes:

"In many ways, the Left has the easier task. These data are tailor-made for the conclusion that a Rawlsian redistributive state is the only answer. For its part, the Right must state forthrightly why it thinks that a free society that tolerates large differences in outcomes is preferable to an authoritarian state that reduces them."

As luck would have it, in the very same issue of The Public Interest last summer that included Murray's essay, there ran another piece which reinforced the view that conservatives will have the harder go of it.

Writing about what can be a tension between economic growth and economic equality, economist Richard T. Gill argued that "our time horizons" as a society have become shorter than they once were. That the "now and immediate" have taken precedence over the "later and deferred."

Which is to say, as our nation becomes less future oriented -- as we invest less stock in the expectation or likelihood of progress for all of our citizens down the road -- then the prevailing view on the part of many likely will become: "Why wait for an uncertain and undependable process of economic growth to raise my living standard? Why not do it right now, by fiat?"

Why not, in other words, up the ante even further when it comes to governmentally orchestrated income redistribution?

Wonderful, partisans of the left might say. But one is obliged to ask: Isn't the United States -- as well as much of the rest of the world -- in the midst of a uniquely successful free-market moment? Hasn't Bill Clinton announced that the "era of big government is over"? Hasn't Laborite Tony Blair been saluted for running Great Britain more in the spirit of Lady Thatcher than Tory John Major ever did?

Before responding and concluding, two points must be made clear.

First, much of what is written about income inequality in the United States is misleading and wrong. For example, while differences in income as measured by quintiles (or any other category) are in fact large and will remain so regardless of whatever public policies are pursued, rarely is it noted that there continues to be remarkable movement by individuals up and down these ladders. Income mobility continues to thrive in the United States, and will persist in doing so, even given Murray's correct cautions.

And second, in writing as I do about intelligence, I do not mean to suggest that IQ alone is destiny -- and Murray doesn't either. Good families, good communities, good teaching, all matter a lot in sculpting children into successful grownups. But the whole point here is that native intelligence matters a lot, too -- certainly more than most politicians, scholars, journalists and other opinion leaders almost ever publicly acknowledge.

Still, and despite the many inherent and routinely demonstrated virtues of both free markets and freedom itself, I'm afraid that Murray is on target when he cites how IQ-measured intelligence will play an increasingly large role in stratifying incomes. With the exception of being real tall and real agile around the basket, just look at the increasing complexity of job skills which are rewarded generously. I'm also afraid he is prescient when he suggests that this will prove to be a rhetorical bonanza for the left.

Am I confident that leaders of the right will be assertive enough in making the case for freedom that Murray says will need to be made? Am I sanguine that Americans will come to refocus adequately on future responsibilities and possibilities? Not nearly as much as I would like to be.

Mitchell B. Pearlstein is president of Center of the American Experiment, a conservative think tank in Minneapolis.