Facebook is all about free speech—or so says Mark Zuckerberg, who delivered remarks to this effect at Georgetown University last week. The remarks were revealing. What they revealed most clearly is that Zuckerberg hasn’t spent enough time thinking about free speech, or about Facebook’s relationship to it.

Zuckerberg got some basic things right. He said that advocacy for social change is impossible without the right to speak freely, that our society is distinctive in the value it has placed on free speech, and that the civil rights struggle would have been even more difficult without the First Amendment victories that civil rights activists were able to win in the U.S. Supreme Court. He noted that social media can be a powerful tool for organizing social and political movements, and for calling attention to injustice (though he neglected to mention that Facebook has sometimes squelched these calls). He said that China denies its citizens the free-speech rights we enjoy here in the United States, and he warned that we shouldn’t take for granted that the internet of the future will reflect our values rather than China’s. Zuckerberg was right about all of this.

But the rest of what Zuckerberg had to say about free speech and Facebook was mainly wrong. Zuckerberg’s most fundamental error was in equating Facebook’s effort to “give people a voice” with “free speech.” The value of a system of free speech has to be measured not just by its effectiveness in promoting individual autonomy—what Zuckerberg calls “voice”—but by its effectiveness in helping us discover truths, understand one another, resolve civic disagreements, and govern ourselves. Any conception of free speech has to be concerned with censorship—including censorship by powerful private actors, like Facebook—but a conception of free speech concerned only with censorship would not do what most of us, whatever our politics, want it to do. A world in which no one’s voice was silenced but the public square was flooded with hate and disinformation would not represent a triumph of free speech.

For this reason, Zuckerberg’s effort to cast himself in the role of free speech champion and his critics in the roles of would-be censors is at best simplistic. It has always been true, of course, that some people—most people—are most enthusiastic about free speech when the speech in question is speech they agree with. But it’s also true that vindicating free speech and “supporting expression” (another of Zuckerberg’s phrases) aren’t the same thing. Facebook’s most trenchant critics aren’t critics of free speech; they’re critics of a conception of free speech that undercuts some of the interests that most people want our system of free expression to serve. These critics are asking Facebook to think more seriously about what free speech actually means, what work it is supposed to do in our society, and what it requires in this new context. That Zuckerberg doesn’t seem to understand this is a problem.

The conceit that Facebook is in the business of enabling users’ voices also obscures the role that Facebook’s own decisions play in determining which voices are heard and which are suppressed. Facebook’s users interact and speak to one another in an environment shaped by Facebook’s interface, algorithms, and policies. What gets said is up to individual users, but it’s Facebook that determines which speech is amplified and which is suppressed. Zuckerberg is surely right that “some people think that giving more people a voice is driving division rather than bringing us together.” But the more powerful critique of Facebook—and the critique Zuckerberg fails to engage or even acknowledge—is that the prevalence of false, hateful, and sensational speech on the platform is a function not of the inherent value or persuasiveness of users’ speech but of Facebook’s decisions. The complaint is not about Facebook’s users, in other words; it’s about Facebook.

Zuckerberg also seemed oblivious to some of the ways in which Facebook actively interferes with our system of free expression. The Knight Institute represents journalists and researchers who study Facebook with digital tools—for example, by using computer code to collect data about the way that disinformation spreads on the platform. This journalism and research is immensely important right now, but Facebook has essentially prohibited it through its terms of service. We approached Facebook more than a year ago to propose that Facebook establish a “safe harbor” that would create space for journalism and research but also protect the privacy of Facebook’s users and the integrity of Facebook’s platform. Facebook was unreceptive. Notably, in Zuckerberg’s speech yesterday, journalism didn’t get even a mention.

Also conspicuously absent from Zuckerberg’s speech was any mention of the surveillance apparatus that underlies Facebook’s platform. Any serious consideration of Facebook and free speech would surely have to grapple with the disturbing fact that Facebook follows its users around the internet, making a note of which stories they share, which articles they read, which websites they visit, and who they communicate with, among countless other details about their expressive and associational lives. The collection and aggregation of this data threaten the privacy that is a precondition for freedom of inquiry, freedom of association, and freedom of expression. Zuckerberg wants to be taken seriously as a defender of free speech, but taking him seriously requires closing our eyes to what Facebook is, and to what it is doing.

Given the other options, it’s good that Zuckerberg wants to be thought of as a digital-age free speech defender. It’s a good thing that he censors speech only reluctantly. But “free speech,” on its own, is a vessel to be filled, not a plan of action. If Zuckerberg wants us to believe that Facebook is giving free speech the consideration it deserves, he needs to move beyond the simplistic notion that free speech just means more and louder voices. He also needs to show an awareness, at least, of the ways in which Facebook is shaping and distorting our system of free expression and undermining the values that free speech is meant to serve.