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One of the more popular criticisms right now against social media platforms like Twitter, Facebook and YouTube is that they’re supposedly biased against conservative viewpoints. U.S. President Donald Trump likes to tweet about it, and numerous members of Congress also believe that to be the case.

Twitter CEO Jack Dorsey — like his counterparts at Facebook and YouTube — has consistently said that his service isn’t biased.

But the people who build Twitter are biased, Dorsey admitted in an interview last month, saying out loud what everyone already knew: Twitter, like most tech companies in Silicon Valley, has a lot more left-leaning employees than right-leaners.

Twitter is so liberal, in fact, that conservative employees “don’t feel safe to express their opinions” within the company, Dorsey told NYU journalism professor Jay Rosen in a new interview published today on Recode Media.

“We have a lot of conservative-leaning folks in the company as well, and to be honest, they don’t feel safe to express their opinions at the company,” Dorsey said. “They do feel silenced by just the general swirl of what they perceive to be the broader percentage of leanings within the company, and I don’t think that’s fair or right.”

Dorsey also explained why he brought up Twitter’s left-leaning employee bias to begin with.

“I think it’s more and more important to at least clarify what our own bias leans towards, and just express it,” he added. “I’d rather know what someone biases to rather than try to interpret through their actions.”

Dorsey’s comments are bound to add fuel to the idea that social platforms like Twitter are suppressing conservative viewpoints, and that Silicon Valley is inherently anti-Trump. It’s a narrative that’s been ongoing for more than two years, and isn’t slowing down. Just this week, far-right news outlet Breitbart published a video of an internal all-hands meeting at Google shortly after the 2016 election in which company executives consoled employees who were upset that Trump won the presidency.

Attorney General Jeff Sessions is even considering a formal investigation to determine whether or not tech giants are indeed suppressing conservative viewpoints.

Twitter, YouTube and Facebook have largely tried to avoid any issues of political bias by relying heavily on software algorithms to determine which content is shown to which users. Software algorithms are written by humans, though, which means they likely have biases as well. Now Dorsey is saying conservative Twitter employees don’t feel comfortable speaking up, which leads to questions about how products at companies like Twitter are made and who has input in making them.

For his part, Dorsey is trying to widen his own feedback loop. Dorsey spoke to Fox News commentator Sean Hannity on his radio show during a recent press blitz and had a number of secret meetings with conservative politicians in Washington this summer to “build ‘trust’ among conservatives who have long chastised the company,” according to the Washington Post.

“We should make sure that everyone feels safe to express themselves within the company, no matter where they come from and what their background is,” Dorsey told Rosen.

Here’s the full interview.

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