Facebook lives and dies by its algorithms. They decide the order of posts in your News Feed, the ads you see when you open the app, and which which news topics are trending. Algorithms make its vast platform possible, and Facebook can often seem to trust them completely—or at least thoughtlessly.
On Thursday, a pitfall of that approach became clear. ProPublica revealed that people who buy ads on Facebook can choose to target them at self-described anti-Semites. The company’s ad-targeting tool allows companies to show ads specifically to people who use the language “Jew hater” or “How to burn Jews” on their profile.
The number of people in those groups alone isn’t large enough to target for an ad, as Facebook will only let advertisers focus on groups of several thousand people. The platform’s ad-selling portal reported, at most, 2,200 self-interested “Jew haters.”
But the anti-Semitic categories can be lumped up into larger groups, which can be targeted. When ProPublica first tried buying an ad, the service suggested that it add “Second Amendment,” presumably because self-described “Jew haters” also expressed an interest in that law. ProPublica declined its suggestion, ultimately targeting fans of Germany’s National Democratic Party, an ultranationalist organization often described as neo-Nazi.
ProPublica does not argue that Facebook actually set up an anti-Semitic demographic that can be targeted by advertising. Rather, it suggests that algorithms—which developed the list of targetable demographics—saw enough people self-describing as “Jew hater” to lump them into a single group.