AP Photo

Gregorio Borgia/AP Images

Police clash with protesters in front of the St. John in Lateran basilica, Rome, Oct. 15, 2011.

On Thursday, my students and I walked along from the Colosseum to the Cathedral of Saint John Lateran in Rome. Two nights later, those same Roman streets became a battleground, as a group of about 1500 black-clad, hooded incognito street fighters succeeded in derailing one of the largest economic protests that has yet been staged in any western country. It had been planned as a huge non-violent demonstration by some 150,000 "Indignati"�"”outraged Italian citizens"”to decry the Berlusconi government's failure to face the global economic crisis, and it was meant to chime in...