I'm a middle school teacher, and I've seen some of my colleagues try and work the same strategies with troubled students, without success, time and again. Kid causes problems, kid is suspended from school. Kid returns to school. Kid causes more problems, is suspended again... and repeat. It takes time and immense patience, but the only way to break the cycle is dialogue and an exchange of ideas. Otherwise, we exist in a state of working to excommunicate, or be excommunicated.Liberals need to focus on formulating ideas and arguments that will prevail in first-order politics instead of trying to preemptively expel from the debate those defending contrary ideas and arguments. Excommunication may appear to succeed in the short term. But in the end, it will often backfire, empowering the excluded opponents in the bargain.