Mr Musk was responding to the Facebook chief’s suggestion he was “irresponsible” for making public statements about his concerns about AI.
In a Facebook Live broadcast on Sunday, a user who said he had “watched a recent interview with Elon Musk and his largest fear for future was AI” asked Mr Zuckerberg: “What are your thoughts on AI and how it could affect the world?”
Mr Zuckerberg said that he had “pretty strong opinions on this. I am optimistic: I think you can build things and the world gets better. But with AI especially, I am really optimistic.
“I think people who are naysayers and try to drum up these doomsday scenarios… I just, I don’t understand it. It’s really negative and in some ways I actually think it is pretty irresponsible.”
He did not mention Elon Musk by name – although he was mentioned in the question.
I’ve talked to Mark about this. His understanding of the subject is limited.
— Elon Musk (@elonmusk) July 25, 2017
The Space X responded on Twitter by dismissing Mr Zuckberg’s knowledge of the subject: “I’ve talked to Mark about this. His understanding of the subject is limited.”
Mr Musk, alongside scientists such as Stephen Hawking, have warned of the potential moment at which artificial intelligence develops the ability to redesign itself.
They warn that if this happens there could be an intelligence explosion as the machine rapidly redesigns itself before humankind could even catch up.
Many researchers fear that this could potentially lead to human extinction.
In 2015, Mr Musk and a number of other backers, pledged $1bn to the non-profit research company OpenAI whose mission is to ensure that artificial general intelligence was built safely.
Facebook has an AI Research team that is staffed by seasoned academic researchers – many of whom were poached directly from their academic posts with promises of increased funding.
This funding and research has helped Facebook publish dozens of academic papers every year, covering advances in the most difficult machine learning tasks – from teaching computers to recognise the contents of an image through to getting them to analyse the notoriously subjective meaning of language as well.