On January 14, 2005 he gave a speech and said (in part):
It does appear that on many, many different human attributes-height, weight, propensity for criminality, overall IQ, mathematical ability, scientific ability-there is relatively clear evidence that whatever the difference in means-which can be debated-there is a difference in the standard deviation, and variability of a male and a female population.He went on to say:
If one supposes, as I think is reasonable, that if one is talking about physicists at a top twenty-five research university, one is not talking about people who are two standard deviations above the mean. And perhaps it's not even talking about somebody who is three standard deviations above the mean. But it's talking about people who are three and a half, four standard deviations above the mean in the one in 5,000, one in 10,000 class. Even small differences in the standard deviation will translate into very large differences in the available pool substantially out.So what does all this mean?
Consider this graph, stolen from La Griffe du Lion:

Even without a statistical difference in mean intelligence scores between men and women, the variation in intelligence scores has a big impact out on the edges. If you're looking for people who are 4 to 5 standard deviations more intelligent than the mean, the difference in variability means you're going to be (inevitably and unintentionally) selecting for men.
La Griffe du Lion's interview subject points out that any randomly selected woman has at least a 45% chance of being more intelligent than any randomly selected man. So if you are looking for smart people, it's not very productive or helpful to simply look for men. But once you have selected your 4- or 5-sigma highly intelligent outliers, there's a strong probability this group will turn out to be dominated by men.
Let's say you are looking to staff a department with people having an I.Q. of 120 or higher. The pool of people with an I.Q. of 120 or higher is going to be about 63% men and 37% women. But you can't simply choose men randomly, because (again) any random woman has a 45% chance of being smarter than any other random man.
This counterintuitive result? A perfectly fair, sex-neutral screening process for people of high intelligence will result in a pool of people containing nearly 2 men for each woman.
This is what tripped up Dr. Summers. He was saying that the difference in result (the number of men versus women employed in the hard sciences) was not proof of systemic sexism. There was no conspiracy or false consciousness behind the easily measured sex ratios; instead, it was a natural outgrowth of the difference in statistical variability between the sexes.
He started his speech by saying:
To take a set of diverse examples, the data will, I am confident, reveal that Catholics are substantially underrepresented in investment banking, which is an enormously high-paying profession in our society; that white men are very substantially underrepresented in the National Basketball Association; and that Jews are very substantially underrepresented in farming and in agriculture.This attack on the basic assumptions of radical feminism (that differences in result can be explained only by group oppression) was a step too far. He came under fire, apparently lost the confidence of the Harvard faculty and was eventually forced to resign.
Dr. Summers' point needs more study and consideration. Even if we assume society (government) should try to encourage fairness and justice, it's important to understand what, exactly, fairness actually looks like. If basic male/female biology leads to the natural result of more men than women at the high (and low) ends of the intelligence spectrum, is it truly fair to strive for a 50/50 balance?





