It's already difficult to talk about politics in a polarized United States, but a few choice words are making it even harder. Columbia linguistics professor John McWhorter says the original meaning of words like "liberalism" and "socialism" have changed. Now such words muddy up political discourse. In this episode, McWhorter talks about the history of political "isms": progressivism, conservatism, fascism, and others. He says the rules that govern why words' meanings change and our social climate have made political terms dynamic and confusing.