The duelling hashtags and their attendant toxicity are a grim testament to our deeply poisoned information ecosystem — one that’s built for speed and designed to reward the most incendiary impulses of its worst actors. It has ushered in a parallel reality unrooted in fact and helped to push conspiratorial thinking into the cultural mainstream. And with each news cycle, the system grows more efficient, entrenching its opposing camps. The poison spreads.Mr. Epstein’s apparent suicide is, in many ways, the post-truth nightmare scenario. The sordid story contains almost all of the hallmarks of stereotypical conspiratorial fodder: child sex-trafficking, powerful global political leaders, shadowy private jet flights, billionaires whose wealth cannot be explained. As a tale of corruption, it is so deeply intertwined with our current cultural and political rot that it feels, at times, almost too on the nose. The Epstein saga provides ammunition for everyone, leading one researcher to refer to Saturday’s news as the “Disinformation World Cup.”At the heart of the online fiasco is Twitter, which has come to largely program the political conversation and much of the press. Twitter is magnetic during huge breaking stories; news junkies flock to it for up-to-the-second information. But early on, there’s often a vast discrepancy between the attention that is directed at the platform and the available information about the developing story. That gap is filled by speculation and, via its worst users, rumormongering and conspiracy theories.On Saturday, Twitter’s trending algorithms hoovered up the worst of this detritus, curating, ranking and then placing it in the trending module on the right side of its website. Despite being a highly arbitrary and mostly “worthless metric,” trending topics on Twitter are often interpreted as a vague signal of the importance of a given subject.There’s a decent chance that President Trump was using Twitter’s trending module when he retweeted a conspiratorial tweet tying the Clintons to Epstein’s death. At the time of Mr. Trump’s retweet, “Clintons” was the third trending topic in the United States. The specific tweet amplified by the president to his more than 60 million followers was prominently featured in the “Clintons” trending topic. And as Ashley Feinberg at Slate pointed out in June, the president appears to have a history of using trending to find and interact with tweets.On Saturday afternoon, a computational propaganda researcher, Renée DiResta, noted that the media’s close relationship with Twitter creates an incentive for propagandists and partisans to artificially inflate given hashtags. Almost as soon as #ClintonBodyCount began trending on Saturday, journalists took note and began lamenting the spread of this conspiracy theory — effectively turning it into a news story, and further amplifying the trend. “Any wayward tweet … can be elevated to an opinion worth paying attention to,” Ms. DiResta wrote. “If you make it trend, you make it true.”That our public conversation has been uploaded onto tech platforms governed by opaque algorithms adds even more fodder for the conspiratorial-minded. Anti-Trump Twitter pundits with hundreds of thousands of followers blamed “Russian bots” for the Clinton trending topic. On the far right, pro-Trump sites like the Gateway Pundit (with a long track record of amplifying conspiracy theories) suggested that Twitter was suppressing and censoring the Clinton hashtags.Where does this leave us? Nowhere good.It’s increasingly apparent that our information delivery systems were not built for our current moment — especially with corruption and conspiracy at the heart of our biggest national news stories (Epstein, the Mueller report, mass shootings), and the platforms themselves functioning as petri dishes for outlandish, even dangerous conspiracy theories to flourish. The collision of these two forces is so troubling that an F.B.I. field office recently identified fringe conspiracy theories as a domestic terrorist threat. In this ecosystem, the media is frequently outmatched and, despite its best intentions, often acts as an amplifier for baseless claims, even when trying its best to knock them down.Saturday’s online toxicity may have felt novel, but it’s part of a familiar cycle: What cannot be easily explained is answered by convenient untruths. The worst voices are rewarded for growing louder and gain outsize influence directing narratives. With each cycle, the outrage and contempt for the other build. Each extreme becomes certain its enemy has manipulated public perception; each side is the victim, but each is also, inexplicably, winning. The poison spreads.