Satoshi Kanazawa

The Scientific Fundamentalist


Women have better things to do than make money I

Why do men on average make more money than women?

Posted Dec 21, 2008

The sex difference in earnings is one of the central concerns of economics and sociology.  Economists and sociologists identify three different parts to the total difference in earnings between men and women.  First, there is the difference in what they call “human capital” – education, job skills, training, and other individual traits that affect productivity and job performance.  Second, sex differences in earnings can be due to occupational segregation by sex – the fact that men and women tend to occupy different jobs.  Men tend to occupy “blue-collar” jobs (manufacturing, construction, truck driving), while women tend to occupy “pink-collar” jobs (secretarial, nursing, teaching).  Third, the sex difference in earnings can be due to sex discrimination, where employers pay equally qualified men and women doing the same job differently.

To the extent that the sex gap in pay is due to differences in human capital and productivity, it is considered to be fair by most social scientists.  To the extent that the sex gap in pay results from the existence of blue- and pink-collar jobs, then paying all workers in a given occupation equally will not close the total sex difference in earnings.  Paying the same wages to male and female truck drivers and to male and female secretaries will not close the sex gap in pay if truck drivers make more than secretaries and most truck drivers are male and most secretaries are female.  The existence of occupational sex segration thus requires consideration of “comparable worth.”

Being deeply wedded to the traditional social sciences and completely oblivious to evolutionary psychology, most economists and sociologists assume that men and women are on the whole identical in their preferences, values, and desires.  They therefore assume that any remaining sex difference in earnings that is not due to sex differences in human capital or sex segragation on the job must be due to employer discrimination.  The existence of discrimination, however, must always be inferred from statistical evidence and cannot be directly observed.  Social scientists are not likely to witness an employer telling the employees, “I’m paying you more because you are a man, and I’m paying you less because you are a woman.”  Nor are employers likely to admit to such a practice if they indeed engaged in it.

The conclusion that there is sex discriminaton by employers crucially depends on the assumption that men and women are on the whole identical, except in their amount of human capital (eduction, job experience, skills) and the jobs that they hold.  If, on the other hand, men and women with the same amount of human capital and in the same jobs are nonetheless inherently and fundamentally different in ways that affect their earnings, for instance, in their preference and desire for earning money, then discrimination becomes unnecessary to explain the sex gap in pay.  If men and women are different in internal preferences and dispositions, such as their desire and drive to earn money, then no external factors, such as employer discrimination or a “glass ceiling,” becomes necessary to explain the sex difference in earnings.

In my next post, I will explain how evolutionary psychology can explain sex gap in pay without resorting to employer discrimination.