Ultimately, Zuckerberg doesn’t address the biggest trade-off: Are these changes compatible with Facebook’s fundamental business model, which relies on a steady supply of user data? If these changes are truly implemented, there will be a substantial business cost to bear. Until he fully answers that, Zuckerberg’s vision of privacy will be incomplete.

The move towards privacy seems designed to respond to a number of problems. To some extent, it responds to Facebook’s content-moderation problem: if a conversation that violates the company’s “community guidelines” is encrypted, such that even Facebook’s software can’t read it, then the company can’t be expected to expunge it. It responds to the Ralph Northam-yearbook problem (“People want to know that what they share won’t come back to hurt them later”), since, by default, content will auto-delete. And it responds to the China problem, as Zuckerberg vows “not to build data centers in countries that have a track record of violating human rights like privacy or freedom of expression.” It also attempts to address Facebook’s public-relations problem: after a scandalous year, fewer people trust the network than ever.

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