Megan McArdle devotes a New York Post column to the type of nationalism America needs now.

“Nationalism” has become a dirty word in the modern era, having become inextricably associated with repression of minorities and imperialist ambition. We’ve forgotten that the nationalists actually did start out in the 19th century with a worthy and difficult project: persuading a large group of people to think of themselves as a single unit.

This was immensely hard work that took most of a century to complete in places such as Italy, Germany and Greece. We fail to appreciate it only because their efforts were so successful that we take the results for granted.

Just how much we take them for granted is reflected on the left, which utters harsh words for nationalism while also constantly engaging in nationalist projects. A welfare state, after all, is a fundamentally nationalistic enterprise, and it is frequently justified on those terms. …

… It’s understandable, and perhaps inevitable, that so many people rejected any hint of nationalism in the aftermath of World War II. But the current political moment illustrates the limits of that approach: The groupish instinct has not gone away, and neither has it leveled up into a mass identification with all humanity.

Instead, it has leveled down, into a global outbreak of populist particularism. That particularism is threatening to tear the United States apart as rival tribes lose the ability to do anything, however trivial, together.

If we are to fight our way back from this soft civil war, we’ll need a muscular patriotism that focuses us on our commonalities instead of our differences.