I don't think they're that bold. The notion that congress is divided more strictly along sectarian lines today than the past is from this paper: https://journal

I don't think they're that bold. The notion that congress is divided more strictly along sectarian lines today than the past is from this paper: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0123507 https://journals.plos.org/plosone/article?id=10.1371/journal... which measures a decrease in cross-party voting over the last few generations. The "common truth" is a bit more subjective, but I've definitely noticed people in my extended social groups having fewer and fewer information sources in common, as well as a smaller and smaller set of common beliefs. I'm not the only person I've come across who's had this impression.