British Prime Minister Theresa May has set her resignation date, a long-overdue result of her failure to deliver on Brexit. She leaves quite a mess for whoever fills the spot of Conservative Party leader in her wake. The party is facing potential political obliteration if it cannot patch itself back together and offer a united vision — including a realistic and executable plan for the U.K.’s divorce from the European Union.

May’s difficulties with Brexit were, mind you, just one of her shortfalls; general incompetence seemed to follow her like a cartoon black cloud, and she harbored a lack of fealty to free-market principles which left her with not much to offer Britons aside from not being Jeremy Corbyn, which could only take her party so far. But there is no question that it was her fumbling of Brexit which did her in.

Her main problem concerning Brexit came down to more than simply her choice of approach or stylistic ubiquities. It was more philosophical than that: In her heart, she didn’t really believe in it, putting her in closer communion with the Continental establishment from whom she was allegedly trying to negotiate a severance than with the majority of her own party, and indeed her own people.

Among the political Left (this is particularly true in Europe and gaining traction in the U.S.), the desire for leveling extends beyond local economic and social conditions to include the world stage. The utopian pursuit of homogeneity is difficult to reconcile with the concept of national sovereignty, explaining the disdain for patriotism as an antiquated relic of a brutal past. Borders are just so, well, bourgeois.

Modern technology has, of course, helped accelerate the erosion of those borders. The internet, air travel, satellite communications, and even the automobile have breached most of the obstacles to trade and travel, smoothing out the sharp edges of distinction between peoples.

But those distinctions have not been erased altogether, and the modernist dilution of the concept of the nation has not eliminated the basic conditions which created it. Nations are more than simply arrangements hammered out by, say, the Congress of Vienna, but are natural outgrowths of peoples tied by common geographic, linguistic, cultural, historic, political, and other bonds.

Conservatism of the kind May was supposed to be representing recognizes this basic reality, that patriotism and national identity are indispensable to the maintenance of a social order. Roger Scruton, Britain’s greatest living political philosopher, writes that “it is allegiance which defines the condition of a society, and which constitutes society as something greater than the ‘aggregate of individuals’ that the liberal mind perceives,” and elsewhere that “territorial loyalty … is at the root of all forms of government where law and liberty reign supreme.”

This is something that seems to still be widely understood, almost subconsciously, inherently, and in a visceral sense. Brits voted for Brexit precisely because they are Brits, as distinguished from French, or Germans, or what have you, united by those same ties of land, language, history, culture, and so much more. The ideal of self-government — a concept which, after all, has its genesis on the British Isles — is incompatible with submission to foreign entities, even ones as relatively benign (if economically and bureaucratically constricting) as the EU.

The rise and increasing success of nationalist parties throughout Continental Europe, witnessed again in last weekend’s EU elections, can be partly explained as a perverse reaction to this forced dissolution of borders and national identity. If patriotism is officially discarded and derided as anachronistic, it should not be unexpected that an ideologized overcorrection could take its place. Disregarding human nature and history bears consequences.

May suffered the consequences of discarding the principles her own party has defended for decades, and if it’s not careful, that party may suffer them with her. It appears likely that Boris Johnson or someone of similar mind will inherit the wreckage. They will face the predictable and ubiquitous challenge: how to maximize the benefits of free trade without giving up too large a degree of political sovereignty. If the next U.K. leader pursues a more direct and realistic exit from the EU, America should be available to help: partly because it is the right thing to do for our greatest ally and partly because further denials of reality could result in decidedly worse consequences.

Kelly Sloan (@KVSloan25) is a Denver-based public affairs consultant, columnist, and the energy and environmental policy fellow at the Centennial Institute.