Prof. Arthur R. Jensen at Berkeley has once more burst forth into the media with his now familiar claim that racial differences in IQ are hereditary. The new studies are based on physical reaction times, which Jensen says differ between blacks and whites.

It is too early for Jensen's new findings to be taken apart and carefully studied by specialists, as they surely will be in time. But anyone who watches basketball will require a lot of convincing that blacks' reactions are slower than whites'. In baseball, where the ball goes from the pitcher's hand to the catcher's mitt in less than a second, blacks have higher batting averages than those of whites.

Jensen's new approach would be more credible if he had paused to deal with evidence that undermined his old approach, which dealt with IQ statistics. Perhaps the most devastating evidence against him was a recent study of black orphans raised by white families. These youngsters had higher IQs than the national average. Their heredity was the same as other black youngsters, but their environment was obviously very different. Jensen has simply ignored that study and gone on to something else.

Statistics on IQs also undermine Jensen's claim. Back around World War I, Americans of Italian, Polish and Jewish ancestry had mental test scores very much like those of blacks today. However, as those groups rose economically and socially, their IQs also rose, and now equal or exceed the national average. Despite the popularity of so-called "Polish jokes," the average IQ of Polish Americans is above the national average -- though 50 years ago it was the same as blacks'. Jensen has also never confronted this evidence.

Perhaps more important than Jensen's theories, or the evidence for or against them, is the social impact of the controversy that has swirled around him for 10 years. The powerful emotions generated on all sides have prevented even Jensen's own position from being accurately reported in the media and have led others to blind, vehement attacks on mental tests themselves, much like the old practice of killing the messenger who brought bad news.

Jensen himself did not use his original study of 10 years ago to argue that black youngsters could not learn in school. On the contrary, he concluded that they could be taught the same material much more effectively by using different teaching methods. This point almost never came out in the sensationalized press accounts of the controversy.

The great tragedy is that the outrage aroused by Jensen's theories has led to the banning of IQ tests in New York and other cities and to paranoid attacks on all kinds of tests or other intellectual standards for jobs, college admissions or admission to the practice of law. But the problem is not that the tests were unfair. The problem is that life is unfair, and the tests are measuring the consequences.

As a child moving from an all-black school in the South to an all-black school in Harlem, I suddenly found myself changed from the top student in my class to the bottom student. The problem was not that the tests were biased. The problem was that my previous education was grossly inadequate. Throwing out the tests would have done no more good than breaking a thermometer when it showed that I had a fever. It was not "fair" that I suddenly found myself trailing all my classmates. But it would have been even more unfair -- and permanetly crippling -- to have kept me unaware of how much work I had to make up.

To take away testing in the school system would hurt black youngsters worse than it would hurt whites. Educated middle-class parents can tell whether the schools are doing a good job or not, and they carry enough political weight to keep the schools from competely neglecting their children's education. Fewer black parents have had the benefit of the kind of education or the kind of political clout that would enable them to keep the schools from shortchanging their children. Test scores at least provide some evidence of what is going on, and even the smallest help in monitoring the school's performance should not be thrown away.

Test scores have been almost superstitiously worshipped for too long. The answer, however, is not an equally irrational refusal to get whatever small help they can provide. IQ tests have their limitations, like everything human. But, used with this in mind, they can be another tool to cope with problems and opportunities.

As for the broader issue of race as an explanation of economic and other success, the complexities go well beyond any of the simple answers in any part of the spectrum. Black West Indians in the United States have incomes very similar to other Americans -- and a higher proportion of African ancestry than American blacks. Second-generation West Indians in the United States have higher incomes than Anglo-Saxons. Obviously, there is much more involved than either race or racism.