The mass shooter who killed 10 people in Buffalo, New York, on Saturday posted a racist manifesto online before targeting a majority-Black neighborhood. His writings took heavily from conservative conspiracy theories that white people were in danger of being replaced by people of color. This so-called Great Replacement conspiracy theory has been promoted by major far-right media figures including Tucker Carlson of Fox News. “What it does is create a dynamic where believers view immigrants and nonwhite people as an existential threat not only to themselves physically but to their position in society,” says Nikki McCann Ramírez, associate research director at Media Matters for America, who has researched how Carlson uses his show to launder white nationalist ideology. We also speak with prominent antiracist scholar Ibram X. Kendi, who says mainstream conservatives are increasingly parroting extremist talking points.