Most people think that the 1st Amendment guarantees free speech. But the philosopher John Stuart Mill argued that free speech requires more than just the absence of legal strictures. The “tyranny of opinion” of the majority has the same effect as censorship enforced by law. When everyone lives “under the eye of a hostile and dreaded censorship” by their fellow citizens, there will be no free inquiry. If Congress “make[s] no law … abridging the freedom of speech,” yet challenging popular opinion gets you fired from your job and made into a pariah, the legal freedom is largely symbolic. Some people may speak their mind and suffer the consequences, but there won’t be free speech.

Mill extolled freedom of speech as a necessary condition for discovering the truth, and he took it for granted that truth is a valuable thing to have. But what about people who don’t want to discover the truth? For them, free speech is the enemy. And since legal protections for free speech are so strong in America, they must resort to extralegal means of silencing those who challenge the lies that they want to protect.

The liberal establishment has become invested in the scientific proposition that men and women have exactly equal distributions of innate abilities and dispositions, and so any disparities in behavior or achievement that we observe are entirely the result of social conditioning and discrimination. Questioning this belief is tantamount to heresy and will have one cast out of his (or her) community, as former Google engineer James Damore so recently learned.

The problem is that the scientific evidence doesn’t support the liberal view. Sex differences in interests emerge within several hours after children are born, with girls showing more interest in people and boys in systems/things. One-day-old girls look longer at faces than one-day-old boys, who spend more time looking at mechanical objects. Our primate cousins, rhesus monkeys, show exactly the same sex differences in interest as young children. Male monkeys prefer to play with trucks, female monkeys with dolls. Two- to three-week-old female macaques look more than males at other macaques’ faces, and four to five weeks after birth they exhibit more “affiliative behaviors.” Returning to humans, the greatest sex disparities in career choice are found in the richest and most egalitarian countries, where individuals have more freedom to pursue their interests. In Sweden, 79 percent of computer systems designers, analysts, and programmers and 97 percent of heavy truck and lorry drivers are men. Meanwhile, 89 percent of child-care workers and 74 percent of people working in research and development in education are women. In contrast, in relatively conservative and less wealthy India, more than 30 percent of computer programmers are women. Only 9 percent of engineers in the U.K. are women, while almost 30 percent of engineers in relatively poor EU countries like Bulgaria and Cyprus are women. Interest in people versus things is tied to prenatal testosterone levels even within sexes: Girls who had higher levels of testosterone in the womb end up with more stereotypically masculine cognitive styles and interests, and conversely for boys.

It is of course theoretically possible that one day we will discover that girls and boys are socialized to have different interests a few hours after they are born (or perhaps in the womb?), or that people are socialized differently depending on their prenatal testosterone levels. But since so far no one has come up with a non-ridiculous theory of how this socialization might work, it seems reasonable to assume that sex differences have (at least in part) a biological basis. The claim that the evidence supports an environmental explanation of all sex differences in interests can only be motivated by ignorance or dishonesty. To protect the men-and-women-are-exactly-the-same theory, the liberal establishment cannot appeal to scientific evidence, so it must resort to silencing dissenters: firing them, making ad hominem attacks, and calling them names.

Last week, one of the world’s two leading science journals, Nature, published an editorial saying:

Difference between groups may therefore provide sound scientific evidence (sic). But it’s also a blunt instrument of pseudoscience, and one used to justify actions and policies that condense claimed group differences into tools of prejudice and discrimination against individuals—witness last weekend’s violence by white supremacists in Charlottesville, Virginia, and the controversy over a Google employee’s memo on biological differences in the tastes and abilities of the sexes.

It’s not clear what the first sentence means—or whether it’s even grammatical—but it seems to be suggesting that it’s possible for there to be differences between groups. The second sentence puts Damore’s memo about female underrepresentation in tech on the same plane as the alleged murder committed by a neo-Nazi in Charlottesville. Really, editors of Nature? Damore citing academic papers about sex-based differences and a deranged neo-Nazi mowing down protesters with a car are examples of the same phenomenon? Needless to say, pushing your favored hypothesis by linking your scientific opponents with evildoers is the crudest, least scientific rhetorical device imaginable—and no one would resort to such a strategy if they could rely on actual science.

The leading popular science magazine, Scientific American, also just published an editorial on sex and gender. It asserts: “arguments about innate biological differences between the sexes have persisted long past the time they should have been put to rest.” It then quotes an article from 122 years ago that discusses the question of whether riding bicycles is bad for women’s health. The lesson for the editors of Scientific American seems to be that to even investigate the possibility of innate sex differences is as ridiculous as investigating whether women should ride bicycles. The implication is that anyone studying sex differences is as benighted and outdated as the troglodyte who wrote that article in 1895. But science is based on evidence, not guilt by circuitous and fanciful association.

Did Google have a right to fire James Damore because he challenged a tenet of political correctness? Most conservatives think that private companies should be allowed to fire people for whatever reason they like. But companies themselves are under legal compulsion to enforce political correctness. What looks like private censorship is actually a form of government censorship by indirect means. Google might not have evolved such a liberal, politically correct culture—or fired Damore—if it didn’t have to protect itself from hostile-work-environment lawsuits or falling afoul of anti-discrimination laws.

A number of commentators, including people connected to Google, have said this more or less explicitly. After the controversy broke out over Damore’s memo, Google’s Vice President of Diversity, Integrity, and Governance Danielle Brown wrote a response saying that “discourse needs to work alongside the principles of equal employment found in our Code of Conduct, policies, and anti-discrimination laws.” Yonatan Zunger, a senior engineer who recently left Google, wrote an article claiming that “not all conversations about ideas even have basic legitimacy.” He concludes that Damore “created a textbook hostile workplace environment.” A number of Google executives read and may have been influenced by Zunger’s article. Explaining why he fired Damore, Google CEO Sundar Pichai quoted the company’s Code of Conduct that requires employees to “create a workplace culture that is free of harassment, intimidation, bias and unlawful discrimination.”

Google executives acted as they did, at least in part, because they feared legally imposed consequences. The government created conditions that encourage private companies to restrict speech among their employees and declare some ideas to not “even have basic legitimacy.” The government should fix the problem that it created. If it can implement protections based on race and gender and religion, it can institute protections for free expression.

But why is it that anti-discrimination laws—which have been on the books for decades—are now interpreted to mean that everyone in the workplace must hold only politically correct beliefs? The new interpretation seems to be motivated by the recently popularized idea that “words are violence.” According to this doctrine (widely accepted on college campuses), expressing non-PC beliefs constitutes violence. Thus, Zunger explains that because Damore created a “hostile work environment,” “a good number of the people [he] might have to work with may simply punch [him] in the face.” According to the old standards, punching someone in the face, not expressing an opinion about a scientific debate, would create a hostile work environment. According to the new standards, Damore initiated the violence by saying something politically incorrect.

Mill argued that free speech is a supremely important social good, which cannot flourish in the face of draconian extralegal censorship. If he is right, then this would provide another justification for using legal measures to protect people from some forms of social retaliation for expressing personal opinions—even if PC corporate culture were not at least partially a creation of government. All sorts of regulations are in place to prevent private individuals and enterprises from damaging public goods. You can’t dump garbage in the Hudson River or burn leaves in your own backyard without a permit because clean rivers and air are valuable. Free speech is also valuable.

As it stands, private companies like Google are allowed to ask their employees to accept that “not all conversations about ideas even have basic legitimacy” or else be fired. It is true that some companies—like partisan publications and religious organizations—are set up for the express purpose of advancing particular opinions and they do have a legitimate interest in what their employees believe. But maybe companies like Google that have no legitimate interest in their employees’ opinions should be forced out of the business of thought policing.