Feminists keep demanding new laws to protect women from the so-called wage gap. Many studies have found that women make about 75 cents for every dollar a man earns. Activists say the pay difference is all about sexism.

 "No matter how hard women work, or whatever they achieve in terms of advancement in their own professions and degrees, they will not be compensated equitably!" shouted Rep. Rosa DeLauro, D-Conn., at a "wage equity" rally in Washington, D.C.

 But how could this be possible? Suppose you're an employer doing the hiring. If a woman does equal work for 25 percent less money, businesses would get rich just by hiring women. Why would any employer ever hire a man?

 Martha Burk, chair of the National Council of Women's Organizations, gave me this simple answer: "Because they like to hire men, John. They like to hire people like themselves and they darn sure like to promote people like themselves." In other words, men so love their fellow men that they are willing to pay a premium of, say, $10,000 on what would otherwise be a $30,000-a-year job, just for the sheer pleasure of employing a man. Nonsense.  It's market competition that sets wages.

 Men do care about money -- and that, not wage discrimination, is why men tend to make more of it.

 "Women themselves say they're far more likely to care about flexibility," says author Warren Farrell. "Men say, I'm far more likely to care about money."

 Farrell spent about 15 years going over U.S. Census statistics and research studies. His research found that the wage gap exists not because of sexism, but because more men are willing to do certain kinds of jobs. "The average full-time working male works more than a full-time working female," Farrell said.

 Farrell illustrates his findings at lectures by asking men and women to stand in answer to a series of questions about job choices, such as whether they work more than 40 hours a week, outdoors or in a dangerous job. Again and again, more men stand.

 Job choices explain the pay difference, Farrell argues in his recent book, "Why Men Earn More: The Startling Truth Behind the Pay Gap."

 They also explain, Farrell said, why more top corporate executives are men. Continued...