Professor Jurgen Zerche was lecturing on political science one day this spring when a band of some 70 young leftists barged into his classroom at the Free University of Berlin and began shouting curses at him. His offense: he had criticized the appointment of a Trotskyite professor. The students warned him that unless he recanted they would hold him prisoner until he starved to death. Zerche escaped by jumping out of a window.
Historian Alexander Schwan nearly met the same fate. His crime was that he had complained that student ideas of justice were similar to those of the Nazis. Another band...