OSHKOSH, Wis.—At first blush, the gathering in Room 212 of the Reeve Memorial Union on the University of Wisconsin at Oshkosh campus looks like any student activity. Students sit around tables in deep discussion. Several pizzas and a cooler of soft drinks are laid out buffet-style on a table in the back. The group of almost 30 students could be a study group, a club meeting, or just friends unwinding after class. But these students are doing more than enjoying pizza and conversation. They are intentionally discussing the most divisive topics of the day with people they know they disagree with as part of “Bridging the Divide,” a program of the Tommy G. Thompson Center on Public Leadership, a nonpartisan institute in the University of Wisconsin....