Dorsey was responding after Facebook, Apple, YouTube and Spotify took down material over the past week published by Jones, reflecting more aggressive enforcement of their hate speech policies and raising pressure on Twitter to do the same.
Dorsey directed readers towards an article further explaining Twitter's rules.
He points out, however, that Alex Jones is not being given a free ride.
The companies that punished Jones said they did so because he violated their policies on hate speech.
With a series of bans and content removal by major technology firms, Jones has complained that there is a coordinated "big tech" agenda to silence him.
"If we succumb and simply react to outside pressure, rather than straightforward principles we enforce (and evolve) impartially regardless of political viewpoints, we become a service that's constructed by our personal views that can swing in any direction", Dorsey wrote.
He is now being sued by the parents of the children murdered in the 2012 Sandy Hook school shooting, having claimed the attack was a hoax. "Sometimes these expressions may be offensive, controversial, and/or bigoted", Twitter said in a Tuesday blog post. "We'll enforce if he does", he said. "This is what serves the public conversation best", Dorsey said.
Dorsey said that it's the responsibility of journalists to "document, validate, and refute" rumors and sensationalized issues spread by accounts like Jones's so "people can form their own opinions".
Fans of Infowars radio host Alex Jones have flocked to the Apple App Store to grab what's left of his voice on social media.
Facebook blocked four of Jones's pages on Monday morning, followed by YouTube's decision to delete his Infowars page, which boasted 2.4 million followers. "The one platform that they CAN'T ban and will ALWAYS have our live streams is infowars.com/show", Jones, who has more than 850,000 Twitter followers, tweeted Monday.
Apple's decision to remove all episodes of Jones' popular show - rather than just specific offending episodes - is one of the largest enforcement actions meant to curb conspiratorial news content by a technology company to date.