What's the biggest threat to Facebook? I think we can figure out what Facebook thinks it is, and there's a big clue in the 90-minute podcast interview Mark Zuckerberg did this week with Kara Swisher, co-founder of Recode.

It's about the single word that Zuckerberg repeated over and over, 35 times in total, during the course of the wide-ranging interview.

That one word? "Responsibility." Take a look:

  1. On protecting elections and stopping fake news on Facebook: "We take that responsibility very seriously," and, "[W]e feel like our responsibility is to prevent hoaxes from going viral and being widely distributed. ...[W]e have a responsibility."
  2. On his personal reaction to reports that fake news on Facebook lead to people's deaths in Myanmar: "I mean, my emotion is feeling a deep sense of responsibility to try to fix the problem."
  3. On Facebook Live broadcasts of tragic events, like assaults and even suicides: "This is terrible, and if this is happening and we can help prevent it, then we have a responsibility to."
  4. On admitting Facebook's shortcomings: "I think that what our responsibility to do is accept when we get things wrong and not be in denial.... I think that that is our responsibility, is to learn as quickly as we can as an organization."
  5. On testifying before Congress: "I didn't feel like my responsibility there was to show up and 'win. ...I view my responsibility as making sure that they can get as much information as they need to in order to inform what they need to go do." 
  6. On leading Facebook when its reputation has taken a hit: "While it may not be the most fun period of running the company, I think we take the responsibility really seriously and get that in the grand scheme of things, I don't think people are being unfair to us."

See what I mean? It goes on from there. Almost no matter what Swisher asks Zuckerberg, he keeps coming back to "responsibility."

Who should be fired at Facebook?

Why so much "responsibility?" Here's another quick clue. At one point, Swisher asks Zuckerberg who Facebook should have fired after the Cambridge Analytica scandal. His response:

"I think it's a big issue. But look, I designed the platform, so if someone's going to get fired for this, it should be me."

Sounds like a bold, brave, "buck stops here" statement--until you realize that when Swisher interviewed Sheryl Sandberg in May and asked her the exact same question, she got the exact same answer:

"Mark has said very clearly on Cambridge Analytica that he designed the platform and he designed the policies, and he holds himself responsible.

"The controls in the company and this are under me, I hold myself responsible for the ones we didn't have."

Of course neither Zuckerberg nor Sandberg is leaving. Nobody's going to be fired.

But boy do those descriptions of Zuckerberg as the guy who "designed the platform," sound familiar, right? Along with the same "buck stops here" sentiment.

This isn't an off-the-cuff answer to a journalist's question. It's a careful communications strategy. And so the question is: Why does Facebook want you to remember "responsibility"?

"You have an enormous amount of power. Do you understand that?"

Facebook is a titan. But titans can fall. And I think this clear, orchestrated message--"we can be trusted; we take responsibility"--tells you a lot about what Facebook sees as its prime weakness.

It's not particularly afraid of any other rival company. It's not government regulation, per se. It's not the threat of being treated like a utility.

It's not even concern about governments in the U.S. or Europe or elsewhere deciding that Facebook is simply an anti-competitive monopoly.

Instead, it's about public sentiment. All those other threats turn on whether people like you and I believe Facebook can be trusted with the immense power it's accumulated--our data, our communities, our connections.

Swisher asks Zuckerberg this directly, telling him that Facebook is seen almost as a "nation-state," and pushing him after he starts talking about responsibility:

"What does that responsibility feel like?...You have an enormous amount of power. Do you understand that? Do you think about that? Or, you don't think you have?"

His reply? More of the same, of course:

"I think we have a lot of responsibility. The community, more than two billion people use our products, and we get that with that, a lot of people are using that for a lot of good, but we also have a responsibility to mitigate the darker things that people are gonna try to do."