Women in Science; DDT and Overpopulation--Posner's Response to Comments
I want to reply to some of the comments on both my last posting, which was on the NAS report on women in science, and also the previous one, on DDT.
Women in Science . I notice that the comments in defense of the NAS report tend to be--defensive; and also emotional. One comment suggests that if a committee 17/18 female is likely to be biased, any male who comments on the report is likely to be biased too. But I did not suggest that the committee should have been composed primarily of men, only that it should have been more balanced, and that the fact that the only man on the committee could not, because of his position, dissent from the report, made his inclusion, as the lone man on the committee, entirely unprofessional. Another commenter vigorously denies that there is any difference between men and women, then states that he prefers female doctors because they are more caring!
A number of comments point to the range of differences between men and women, encompassing behaviors (crime, sports), preferences, test results, psychology, and much else besides, including the tendency of women in science to prefer the less mathematical fields (I gave the example of primatology). These differences could I suppose all be the product of discrimination, but that seems highly unlikely.
One comment states that the underrepresentation of women in science may be a result of path dependency (where you start may determine where you end up)--the fewness of women in science in past times. This is not persuasive, because there were virtually no women in academic law when I was a law student in the 1950s, but now about half of all law professors are women.
One last point: a good test for whether there is discrimination against or in favor of a group is its average performance in the profession alleged to be a site of discrimination relative to that of the majority. If women were discriminated against in science, one would expect the average woman in science to outperform the average man in publications, awards, etc., simply because only women who were better than men could overleap the discrimination hurdle. But if there is discrimination in favor of women in science, then the average man should outperform the average woman, because then it is the men who have to overcome the discrimination barrier. (If there is no difference in average performance of men and women in a given field, the inference is that there is no sex discrimination in that field--employers and other performance evaluators regard sex as irrelevant.) Since men outperform women in science rather than vice versa, the inference is that there is discrimination in favor of women.
DDT and Overpopulation I repeat my abject apology for calling DDT a herbicide rather than a pesticide. Some comments suggest that the mistake reveals my complete incompetence to discuss environmental issues. That seems a bit harsh. The reason for the mistake was simply that herbicides play a particularly important role in diminution of genetic diversity--thanks in part to the ban on DDT--so I was thinking about herbicides when I was considering the effects of DDT.
Some comments point out correctly that interior spraying won't eliminate mosquitoes and therefore malaria; and that is true. But complete eradication may not be cost justified. Costs and benefits must be compared at the margin. If 99 percent of deaths from malaria can be eliminated by interior spraying, it may not be worthwhile to spend billions of dollars developing and producing a vaccine. That is why I find the Gates Foundation's campaign to eradicate malaria puzzling. (Actually, I don't think it's very puzzling. There is often a strong political and public-relations dimension to foundation giving, even foundation giving for activities thought nonpolitical, such as saving lives. Somehow giving money to spray the interior of houses with DDT lacks pizzazz and could even be thought politically incorrect.)
Most of the comments fasten on the following paragraph in my posting: "Not that eliminating childhood deaths from malaria (I have seen an estimate that 80 percent of malaria deaths are of children) would be a completely unalloyed boon for Africa, which suffers from overpopulation. But on balance the case for eradicating malaria in Africa, as for eradicating AIDS (an even bigger killer) in Africa, is compelling. Malaria is a chronic, debilitating disease afflicting many more people than die of it, and the consequence is a significant reduction in economic productivity." Many commenters regard "unalloyed boon" as a particularly callous chardacterization. I think some of the commenters don't understand the meaning of the word "unalloyed." I did not say it was a good thing that children die of malaria; I just said that it was not just a good thing, if the deaths reduce population. Now, they may not, as one comment explains, because a family that loses a child to malaria may decide to have another child in its place, and indeed if the family is risk averse it may end up having more children because of the high risk of losing one or more of them to malaria than if there were no such risk. That is an interesting empirical question. I suspect that on balance there will be fewer children surviving to adulthood, simply because of the cost of additional children.
I continue to insist that overpopulation, including in subsaharan Africa, is a real problem. It is true but absurdly irrelevant that New York City has a greater population density than Africa. Overpopulation is not a simple matter of dividing people by square miles. In an agricultural society, population density tends to be negatively correlated with wealth, simply because the land must be worked harder to obtain food. Good land is not the only resource that is in limited supply--so is fresh water, forest products, game, and mineral resources. Scarcities in these resources can be overcome, but only at a cost. It is true as several comments point out that as a society grows wealthier, the birthrate tends to drop (the "demographic transition"), but Africa seems to be trapped by extreme poverty exacerbated by overpopulation.
Is it foolish for China to try to limit its population? If not, the case for limiting the African population is much stronger, because Africa has a far less productive population.
And so far I have been speaking only of the effects of population on the populous country. There are external effects as well. The effects of population on the destruction of forests and on the demand for electricity and cars are major contributors to global warming.