Even if you solve the problem going forward, there’s still this issue of: Are there other Cambridge Analyticas out there, or other Kogans who, when the platform worked a certain way in the past, were there apps which could have gotten access to more information, and potentially sold it without us knowing, or done something that violated people’s trust? We also need to make sure we get that under control. That’s why we spent a lot of time figuring out, O.K. here’s what it’s going to take to do a full investigation of every app that got access to a large amount of information before we changed the platform policies to dramatically reduce the data access that developers had. For any app that we uncover that has any suspicious activity, we’re going to go do a full forensic audit, and make sure we have the capacity to do that, to make sure that other developers aren’t doing what Kogan did here.

The third thing is, it’s really important that people know what apps they’ve authorized. A lot of people have been on Facebook now for five or 10 years, and sometimes you signed into an app a long time ago and you may have forgotten about that. So one of the steps we’re taking is making it so apps can no longer access data after you haven’t used them for three months.

But it’s also just really important to put in front of people a tool of, here are all the apps you’ve connected to and authorized, here’s an easy way to deauthorize them, to revoke their permission to get access to your activity.

Kevin Roose: Is Facebook planning to notify the 50 million users whose data was shared with Cambridge Analytica?

Zuckerberg: Yes. We’re going to tell anyone whose data may have been shared.

Now, there’s a question of whether we have the exact record in our systems today of who your friends were on that day when there was access three and a half or four years ago, so we’re going to be conservative on that and try to tell anyone whose data may have been affected, even if we don’t know for certain that they were. It’s likely that we’ll build a tool like we did with the Russian misinformation investigation, that anyone can go to it and see if their data was affected by this.

Roose: Do you have a preliminary estimate of how many apps you’ll be investigating?

Zuckerberg: It will be in the thousands.

Frenkel: Were those app developers notified that you’ll be investigating this yet?

Zuckerberg: Just when I posted. And we’ll be reaching out in the near term.