How did our politics become so polarized? Author Marc C. Johnson offers his answer in his talk on his new book, 'Tuesday Night Massacre: Four Senate Elections & The Radicalization of the Republic Party.' 1980 was the year that the party of Lincoln veered right, and outside interests helped defeat four Senate liberals — including John C. Culver, the namesake of the Culver Center for Public Policy at Simpson College. Johnson argues that Republicans have stayed on that rightward track for more than 40 years, climaxing in the presidency of Donald Trump.