He also addressed critics who believe that Facebook has not done enough to combat fake news, including posts that some people said influenced the presidential election - an idea which Zuckerberg previously called "pretty insane".
"Facebook stands for bringing us closer together and building a global community". In an interview with BuzzFeed, Zuckerberg said that Facebook can save "people's lives" by using AI to detect signs of bullying or self-harm.
In a wide-ranging post of almost 6,000 words, Zuckerberg said Facebook can play a role in bringing people together as they face fractious politics and anti-globalization sentiment.
President Trump campaigned on a platform of stronger borders and rethinking global trade deals and alliances. "I hear fearful voices calling for building walls".
"In times like these, the most important thing we at Facebook can do is develop the social infrastructure to give people the power to build a global community that works for all of us". The company will still connect people, as its old mission spelled out, but it also must help get us to a global community. It can help build a supportive, safe, informed, civically-engaged and inclusive worldwide network, his letter states in bullet points.
This doesn't mean Facebook will change, per se.
"Our greatest opportunities are now global - like spreading prosperity and freedom, promoting peace and understanding, lifting people out of poverty, and accelerating science", he wrote. As The New York Times points out, his manifesto is a literal update of the founder's letter Zuckerberg posted when Facebook when public in 2012, which he hasn't updated since (bucking the annual rewrite most executives do to outline goals in the new year).
"The approach is to combine creating a large-scale democratic process to determine standards with AI to help enforce them", Zuckerberg said.
Overall, Zuckerberg advocates that integrating Facebook more completely into everyone's day-to-day will fix what he sees as humanity's increasingly threadbare social ties.