“Anyone capable of living outside a city,” wrote Aristotle, “must either be a beast or a god.” Before taking offense or pride in that aphorism, the rural should know that the Greek for “city” here is polis, and the polis of classical Greece was not a city in our sense. It was smaller than a nation, to be sure, but unlike London or Washington, it was a sovereign state. Every human individual, Aristotle is saying, must live within such a group—whether it be a tribe or an empire. To lack such a polis, to live truly alone, would require the independence of a wild animal or the self-sufficiency of a god. We need groups to survive; we need someone else to do our hunting or growing, someone else to make our clothes and build our houses, someone else to fix our furnace and perform our surgeries. But the polis does more than help us survive. It encompasses the family, the school and the broader culture, all of which shape who we become. Without such groups, …