For a few hundred years, the notion that women are capable of completing tasks historically completed by men has gradually become more popular.

Currently most U.S. schoolteachers are female. As late as the 1840s, however, it would have been uncommon—although not entirely unheard of—for a school to employ a female teacher.

Let’s say you had a time machine and went back to the year 1835, and someone asked you the question: “Why are there so few female teachers?”

A free-marketeer might look at the status of the labor market for teachers and say: “The invisible hand has wiggled it thus! If women were as good at teaching, any schools that refused to hire women would be edged out of the marketplace by the schools that do hire women. The only explanation can be that women are inferior teachers to men.”

The same sort of mistake could be made if you were to go back seven more centuries to medieval France and ask: Why are there so many stretchers and so few wheelbarrows? Once again, a naïf might surmise that stretchers must be better at carrying things than wheelbarrows are. With a furrowed brow, and a very serious voice, you might insist, “If wheelbarrows conferred an economic advantage, nobody would be using stretchers.”

As it were, if you carried a pile of manure from East to West Campus in a wheelbarrow, it would take you only half as much energy as if you carried it in a stretcher. In the 1100s in France, wheelbarrow technology was spreading, but slowly. If you were to wait a few hundred more years, you could’ve walked all around Europe and seen lots of wheelbarrows and almost no stretchers.

There are at least two big similarities between the idea employees should be hired and paid according to their relevant experience, exhibited talent and work ethic, not according to their gender and the idea that wheelbarrows are more efficient at carrying things than stretchers. One: Both are good business practice. Two: Both ideas could take centuries to disseminate. Even when airtight evidence is readily available about the benefits of a new idea, habit, stubbornness or deeply entrenched biases can prevent people from changing their minds. One thing that distinguishes women from wheelbarrows is that women have feelings and goals; some might even say that women deserve to be treated fairly, in a way that wheelbarrows do not. The “long run” can take a very long time indeed—and if women are being unjustly discriminated against because of antiquated attitudes, that’s a very real “short term” problem.

Equal pay laws do not guarantee that men and women will be paid the same amount—they guarantee both men and women legal recourse if they have evidence to show that their employers are paying different wages not on the basis of their work product but on the basis of gender.

Some might say, “It’s not 1835, surely employers have caught on to the idea that gender discrimination is bad business.” But, indeed, they have not! In 2012, researchers at Yale performed a study with college professors in biology, physics and chemistry departments at six major research universities; all the professors received nearly identical CVs, detailing the exact same accomplishments and skills. The CVs were alike in every way—except for the name at the top. The professors who read “John’s” resume, instead of “Jennifer’s,” evaluated him as more competent, said they were more likely to hire him for their laboratories and offered him an average starting salary that was 14 percent higher than Jennifer’s. As a woman graduating Duke this year, the idea that I could be paid 14 percent less, year after year, than a male with the exact same abilities as me, alarms me. Fourteen percent annually is, for some women, the difference between living in poverty and the middle class, between precarity and security.

I am glad that the 1964 Civil Rights Act gives me legal recourse if I find out that my employer is paying me less on the basis of my gender or race. I don’t think anyone should be refused a job, paid less or be harassed at work for being Buddhist or Jewish or black or white or male or female. Of course, it’s not easy to prove why your employer is paying you less; because of the high burden of proof, it’s rare that individuals take pay discrimination to court and are successful.

I chose my majors—economics and math—because I think market forces are among the most powerful forces in our society, but I think you’re profoundly foolish if you look at our globe’s sexism or racism or climate change or children in poverty and say: This is how it has to be because the market tells me so.

Elena Botella is a Trinity senior. Her column runs every Thursday. You can follow Elena on Twitter @elenabotella.