Like McCarthyism during the Red Scare of the 1950s, ex-President Donald Trump's "Stop the Steal" movement seeks to vilify powerful, internal enemies who are trying to undermine American society. In this episode, McCarthyism Redux, historian Gary Gerstle identifies the reasons why such conspiracy theories take hold in the public mind. It is no surprise, when politics are so polarized, that some people are quick to believe the worst about others with whom they disagree.