“I am neither celebrating nor proud of having to ban Donald Trump on Twitter, or how we got here,” he wrote.
“After a clear warning that we would take this action, we made a decision with the best information we had based on threats to physical security both on and off Twitter.”
He said he believed the ban was the right decision.
“We faced an extraordinary and unsustainable circumstance, which forced us to focus all our actions on public safety,” he said.
“The offline harm as a result of online speech is demonstrably real, and what drives our policy and compliance above all.”
Dorsey wrote that banning an account has “real and significant ramifications.”
“While there are clear and obvious exceptions, I believe that a ban is our ultimate failure to promote healthy conversation.
“And a moment for us to reflect on our operations and the environment that surrounds us.”
He admitted that such a ban sets a dangerous precedent.
“Control and accountability for this power has always been the fact that a service like Twitter is a small part of the larger public conversation that takes place on the Internet,” Dorsey wrote.
“If people don’t agree to our rules and compliance, they can just go to another internet service.”
Dorsey said he did not believe that the other bans Trump faced on Facebook, Instagram, YouTube and others were coordinated.
“More likely: companies reached their own conclusions or were emboldened by the actions of others,” he said.
“This moment in time may require this dynamic, but in the long run it will be destructive to the noble purpose and ideals of the open Internet.
“A company that makes the decision to moderate itself is different from a government that eliminates access, but it may feel the same way.”
Dorsey said that Twitter was funding an initiative to create a decentralized standard for social media.
“Efforts to censor, cancel and blacklist our fellow citizens are wrong and dangerous,” he said.
“What is needed now is that we listen to each other, not silence ourselves.”
It did not specifically mention the deletion of its own Twitter, Facebook and Instagram accounts after its posts were seen as encouraging violence.
Meanwhile, Trump will be permanently banned from Snapchat when he leaves office.
The social media giant had suspended Trump’s account indefinitely last Wednesday, but Axios reports that the account will not be reactivated.
Snapchat was the first of the social media companies to block Trump’s account, citing violations of his policies against the spread of hate and the fomentation of violence.
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Snapchat is not considered one of Trump’s preferred social media platforms, but his campaign regularly used it in an attempt to reach younger voters.