THE age of Trump has inspired soul-searching within our overclass — long nights reading “Hillbilly Elegy,” mostly — but also a wave of cosmopolitan pride. During the presidential campaign, when Trump talked about making America great again, Hillary Clinton countered that “America is already great” — meaning, of course, dynamic and diverse and tolerant and future-oriented, all the things that Trump seems to dismiss and his voters seem to fear.

This great-already sentiment has been reproduced in many elite quarters, and last week the Niskanen Center’s Will Wilkinson, writing in The Washington Post, brought it to a particularly sharp point: What’s really great about America is its big, booming, liberal cities.

Trump loves to talk down America’s great metropolises, Wilkinson points out, portraying them as nightmares out of “Death Wish” or “Dog Day Afternoon.” Wilkinson says that’s because our president needs “to spread the notion that the polyglot metropolis is a dangerous failure” to advance his nativist agenda. But in reality our cities are, yes, already great — safer-than-ever, culturally-rich, rife with policy innovation, and driving our economic future. They’re places where immigrants flock and college graduates increasingly cluster, compounding their talents through cooperation and exchange, generating new ideas and innovations while the Trumpish hinterland languishes in resentment and nostalgia.

I respectfully dissent. Yes, for many of their inhabitants, particularly the young and the wealthy, our liberal cities are pleasant places in which to work and play. But if they are diverse in certain ways they are segregated in others, from “whiteopias” like Portland to balkanized cities like D.C. or Chicago. If they are dynamic, they are also so rich — and so rigidly zoned — that the middle class can’t afford to live there and fewer and fewer kids are born inside their gates. If they are fast-growing it’s often a growth intertwined with subsidies and “too big to fail” protection; if they are innovation capitals it’s a form of innovation that generates fewer jobs than past technological advance. If they produce some intellectual ferment they have also cloistered our liberal intelligentsia and actually weakened liberalism politically by concentrating its votes.