Once we recognize that large differences in achievement among races, nations and civilizations have been the rule, not the exception, throughout recorded history, there is at least some hope of rational thought - and perhaps even some constructive efforts to help everyone advance.
Even such a British patriot as Winston Churchill said, "We owe London to Rome" - an acknowledgement that Roman conquerors created Britain's most famous city, at a time when the ancient Britons were incapable of doing so themselves.
No one who saw the illiterate and backward tribal Britons of that era was likely to imagine that someday the British would create an empire vastly larger than the Roman Empire - one encompassing one fourth of the land area of the earth and one fourth of the human beings on the planet.
History has many dramatic examples of the rise and fall of peoples and nations, for a wide range of known and unknown reasons. What history does not have is what is so often assumed as a norm today, equality of group achievements at a given point in time.
Roman conquests had historic repercussions for centuries after the Roman Empire had fallen. Among the legacies of Roman civilization were Roman letters, which produced written versions of Western European languages, centuries before Eastern European languages became literate. This was one of many reasons why Western Europe became more advanced than Eastern Europe, economically, educationally and technologically.
Meanwhile, the achievements in other civilizations - whether in China or in the Middle East - surged ahead of achievements in the West, though China and the Middle East later lost their leads.
There are too many zig-zags in history to believe that some single over-riding factor explains all, or even most, of what happened, either then or now. But what seldom, if ever, happened were equal achievements by different peoples at the same time.
Yet today we have bean counters in Washington turning out statistics that are solemnly presented in courts of law to claim that, if the numbers are not more or less the same for everybody, that proves that somebody did somebody else wrong.
If blacks have different occupational patterns or different other patterns than whites, that arouses great suspicions among the bean counters - even though different groups of whites have long had different patterns from each other.
When American soldiers were given mental tests during the First World War, those men of German ancestry scored higher than those of Irish ancestry, who scored higher than those who were Jewish. Mental test pioneer Carl Brigham said that the Army mental test results tended to "disprove the popular belief that the Jew is highly intelligent."
An alternative explanation is that most German immigrants came to the United States decades before most Irish immigrants, who came here decades before most Jewish immigrants. Years later, Brigham admitted that many of the more recent immigrants grew up in homes where English was not the spoken language and that his earlier conclusions were, in his own words, "without foundation."
By this time, Jews were scoring above the national average on mental tests, instead of below. Disparities among groups are not set in stone, in this or in many other things. But blanket equality of outcomes is seldom seen at any given time either, whether in work skills or rates of alcoholism or other differences among the various groups lumped together as "whites."
Why then do statistical differences between blacks and whites set off such dogmatic assertions - and "disparate impact" lawsuits - when it is common for different groups to meet employment or other standards to different degrees?
One reason is that "disparate impact" lawsuits require nothing more than statistical differences to lead to verdicts, or out-of-court settlements, in the millions of dollars. And the reason that is so is that so many people have bought the unsubstantiated assumption that there is something strange and sinister when different peoples have different achievements.
Centuries of recorded history say otherwise. But who cares about history any more? Certainly not as much as they care about the millions of dollars available from "disparate impact" lawsuits.
Thomas Sowell is a senior fellow at the Hoover Institution at Stanford University. His website is www.tsowell.com.