“Extremists” are one of the famous bogeymen that American politicians invoke to sanctify their own power. But the definition of “extremism” has forever been in flux. The only consistent element in definitions of extremism is that politicians always win. In the 1770s, people who suggested that the king of England had no right to rule America were considered extremists. Even a 2013 Pentagon instructional document declared that “the colonists who sought to free themselves from British rule” were...
