Social media giants contribute to global conflicts and allow misinformation. How have they gained so much control, and what is that doing to our lives?

It’s good to remember that every time Mark Zuckerberg claims that he founded Facebook in order to connect people or build communities, he is somehow forgetting that he first created the site in order to enable himself and his fellow dorm-dwellers to rate Harvard’s young women on their looks. But then, Zuckerberg has never been the sharpest tool in the box. He once said that Facebook wouldn’t interfere with Holocaust-denial on its service, because it was hard to impugn people’s motives for denying the Holocaust, before a couple of years later announcing that his “thinking” on the matter had “evolved” and Holocaust denial was now frowned upon. Well, evolution does work slowly.

But as Charles Arthur’s coolly prosecutorial book shows, social-media algorithms don’t just allow people with nefarious interests to get together: they perform as active matchmakers. “Facebook was hothousing extremism by putting extremists in touch with each other,” concluded Facebook’s own internal investigations in 2016. Not only that, Facebook was “auto-generating terrorist content”: its “machine learning” systems created a “Local Business” page for “al-Qaida in the Arabian peninsula”.