Facebook on Tuesday responded to a report in Gizmodo that it had allowed curators to suppress stories from conservative publications in its Trending Topics module.

Tom Stocky, Facebook’s VP of search, wrote in a post, in part:

We take these reports extremely seriously, and have found no evidence that the anonymous allegations are true.

Facebook is a platform for people and perspectives from across the political spectrum. There are rigorous guidelines in place for the review team to ensure consistency and neutrality. These guidelines do not permit the suppression of political perspectives. Nor do they permit the prioritization of one viewpoint over another or one news outlet over another. These guidelines do not prohibit any news outlet from appearing in Trending Topics[…]

[…]We have in place strict guidelines for our trending topic reviewers as they audit topics surfaced algorithmically: reviewers are required to accept topics that reflect real world events, and are instructed to disregard junk or duplicate topics, hoaxes, or subjects with insufficient sources. Facebook does not allow or advise our reviewers to systematically discriminate against sources of any ideological origin and we’ve designed our tools to make that technically not feasible. At the same time, our reviewers’ actions are logged and reviewed, and violating our guidelines is a fireable offense.

There have been other anonymous allegations — for instance that we artificially forced ‪#‎BlackLivesMatter‬ to trend. We looked into that charge and found that it is untrue. We do not insert stories artificially into trending topics, and do not instruct our reviewers to do so. Our guidelines do permit reviewers to take steps to make topics more coherent, such as combining related topics into a single event (such as ‪#‎starwars‬ and ‪#‎maythefourthbewithyou‬), to deliver a more integrated experience.

Our review guidelines for Trending Topics are under constant review, and we will continue to look for improvements. We will also keep looking into any questions about Trending Topics to ensure that people are matched with the stories that are predicted to be the most interesting to them, and to be sure that our methods are as neutral and effective as possible.

Gizmodo had quoted unidentified sources who worked as Facebook “news curators” — “a small group of young journalists, primarily educated at Ivy League or private East Coast universities” — in contract positions between 2014 and 2015. One former curator with conservative political views told Gizmodo, “I’d come on shift and I’d discover that CPAC or Mitt Romney or Glenn Beck or popular conservative topics wouldn’t be trending because either the curator didn’t recognize the news topic or it was like they had a bias against Ted Cruz.”

Stocky’s post, however, makes it clear that Facebook’s curators would be allowed to “disregard…hoaxes,” which would presumably include, for instance, stories that claim President Obama is not a U.S. citizen.

On Monday, the conservative site RedState noted it had “certainly never observed any of the behavior that is alleged in the article being targeted at us, specifically.” Leon H. Wolf wrote:

We understand that we are categorized by Facebook as “advocacy” rather than “news,” which the exact same way Google characterizes us. We aren’t CNN, and we don’t really expect to be treated like CNN — but we would hope that Facebook would treat us equivalently with similar left-leaning outlets: if TPM is “news” then so are we.

In the comments of the post, Eric Davis, a member of the Google Android security team, had an idea:

And Stratechery’s Ben Thompson reminded us again that algorithms, since they’re created by humans, are never neutral — and that anything in the trending topics module arguably does less to create polarization than what we see in our News Feeds:

Facebook is receiving a huge amount of criticism for allegedly biasing the news via the empowerment of a team of human curators to make editorial decisions, as opposed to relying on what was previously thought to be an algorithm; it is an algorithm, though — the algorithm that powers the News Feed, with the goal of driving engagement — that is arguably doing more damage to our politics than the most biased human editor ever could. The fact of the matter is that, on the part of Facebook people actually see — the News Feed, not Trending News — conservatives see conservative stories, and liberals see liberal ones; the middle of the road is as hard to find as a viable business model for journalism (these things are not disconnected).