Why are ambulances attacked by rock-throwing youths in Sweden? And how should Germany deal with a recent surge in clan-based crime?  Mark S. Weiner is a professor of legal history, a scholar of multiculturalism and the author of The Rule of the Clan: What an Ancient Form of Social Organization Reveals About the Future of Individual Freedom. Quillette’s European editor Paulina Neuding spoke to him in Stockholm, Sweden. Weiner is currently on a Fulbright scholarship at Uppsala University, where he is teaching about American constitutional law, collaborating with Swedish scholars of prehospital medicine—and riding along with paramedics in immigrant and other neighborhoods. What follows is an edited reproduction of that interview.   *   *   * Paulina Neuding: Sweden has experienced a rise in violence against first responders in recent decades, including rock throwing against paramedics in the country’s “vulnerable areas.” How do you explain this phenomenon? Mark S. Weiner: The easy answer is that Sweden has a growing population of alienated young men, and ambulances are representatives of social and government authority. If I were …