“That’s not who we are.” So said President Obama, again and again throughout his administration, in speeches urging Americans to side with him against the various outrages perpetrated by Republicans. And now so say countless liberals, urging their fellow Americans to reject the exclusionary policies and America-first posturing of President Donald Trump.

The problem with this rhetorical line is that it implicitly undercuts itself. If close to half of America voted for Republicans in the Obama years and support Trump today, then clearly something besides the pieties of cosmopolitan liberalism is very much a part of who we are.

This self-undermining flaw makes the trope a useful way to grasp the dilemmas facing Trump’s opponents. In seeking to reject Trump’s chauvinist vision, they end up excluding too much of what a unifying counternarrative would require.

The exclusion happens by omission, in the course of telling a story about America that’s powerful but incomplete. In this narrative, which has surged to the fore in response to Trump’s refugee and visa policies, we are a propositional nation bound together by ideas rather than any specific cultural traditions — a nation of immigrants drawn to Ellis Island, a nation of minorities claiming rights too long denied, a universal nation destined to welcome foreigners and defend liberty abroad.