Campaign promises matter. Despite the popular wisdom that promises made on the campaign trail are little more than political posturing and abandoned when no longer convenient, research shows that politicians are surprisingly successful at fulfilling their major campaign promises. But the transmutation of proposal into policy is an imperfect one, pitting unilateral optimism against messy compromise.

Rarely has this asymmetry been laid barer than in the twin cases currently confounding governments on both sides of the Atlantic: President Trump’s border wall and Britain’s exit from the European Union. They are striking cases of what happens when campaign promises are reduced to bare simplicities and divorced from the realities of policymaking. In pursuit of better governance, we must interrogate the system of incentives that encourages these phenomena. The present bedlam should instruct and restrain future candidates; regrettably, the lesson may already be going unlearned.

A 1984 review found that, as a whole, U.S. presidents from Wilson to Carter kept 75 percent of their campaign promises; a separate overview of 21 countries found that political parties kept an average of 67 percent of their promises. Even when unfulfilled, policy pledges communicate what kind of a person the candidate is and where they will focus their limited resources once in office. Infamous historical reneges like George H.W. Bush’s tax policy have branded the consequences of spectacular reversal into the political psyche.

This fealty to campaign audiences and eager bases can help explain the fervor with which politicians are doggedly pursuing a pair of promises — oaths made at campaign stops, amidst soaring oratory, in pursuit of singular visions rather than political pragmatism.

Both Brexit and the border wall were signature campaign promises that garnered enormous enthusiasm (albeit directed towards a referendum in the U.K., not an election). Both campaigns were successful despite overwhelming mainstream skepticism. And both, following their stunning victories, have resulted in massive political gridlock — the longest government shutdown in American history on the one hand and uniquely unparalleled chaos and uncertainty throughout the U.K. on the other.

This is the legacy of stump speech declarations, panacean in their simplicity. This is the grim absurdity of forcing reductionism into sober lawmaking bodies. This is the seam between the purity of promises and the restraints of practical policy.

Proponents of both policies seemed uninterested in the complications of turning their proposals into law. The Brexit “Leave” campaign still exists in the shadow of the debunked “Brexit Bus” as well as widespread accusations that blatant misinformation fueled the vote to leave. “Brexiteers” repeatedly inflated the injustices that the EU was hoisting upon Britain and downplayed the difficulty of extracting themselves from the union. Their solution implied untold complications and unprecedented political negotiations but was boiled down to niceties; simply tell the EU “no thanks.”

President Trump repeatedly insisted that Mexico would pay for a “border wall,” even going out of his way to rebuke attempts at watering down his intransigence. He insisted that it would be paid for, it would be beautiful, it would be easy — and only he could do it. Deep into the shutdown, the precise conceptualization of the wall became a major sticking point for a compromise; what would the president settle for? A barrier? Steel slats? Did Trump want the wall finished or newly built? Had he ever actually said that Mexico would pay for it? The goalposts for victory were never definitively set; the contours of the most transformative immigration policy in modern American history seemingly settled on the fly.

In both cases, symbolism and victory were elevated above achievability and legislation. Each proposal had the gleam of an idealism that could only survive in the sheltered limbo of a campaign. Each set of proponents wielded an emotional populist fervor and cast their detractors as uncaring globalist elites. And each brushed off attempts to push them on the details of their packages, insisting that things were straightforward, that they would get done, that it would all be “one of the easiest things in human history.”

Now, gridlock and dysfunction wrack the sister nations as elected officials, beholden to their unbending promises, try to build structures of law on the shifting sands of ambiguous vows.

Campaign promises are unitary, one-directional affairs — asserted, imposed, propagated. The set of incentives is different and barely overlaps with those of making policy, balancing opposing interests, and seeking workable resolutions. Mitch McConnell and Ann Coulter have vastly different constituencies and responsibilities, as Newt Gingrich (of all people) has noted.

Politicians must be attuned to all constituents, not simply the loudest or most obstinate. So long as the mandate of accountable, representative government is unchanged, politicians’ rhetoric and responsibilities should be consistent on either side of election day.

Lest one infer that this trend was merely a 2016 affair, the Democratic presidential candidates for 2020 have already begun entertaining increasingly bold policy proposals. Universal healthcare, free college education, a Green New Deal, reparations for slavery — the ideals have been lofty, the acknowledgments of the limitations of progressive policymaking under divided government scarce (see: the notable and much marveled-over exception of centrist Amy Klobuchar’s willingness to simply say, “no”).

Riding the progressive fervor catalyzed by Trump’s election, Democratic hopefuls are pushing bombast before nuance, thereby mimicking the populist they hope to oust. The border wall and Brexit are not alone in the annals of overinflated, underdeveloped policy pronouncements; the field may only be crowding. “Oh, it’s impractical. Oh, it’s too expensive. Oh, it’s all this,” Cory Booker has said about the feasibility of progressive moonshots. “If we used to govern dreams that way, we would have never gone to the moon.”

The system that rewards promises, burnished clean of the blemishes of eventual legislative passage, is a collective one, stitched together by willing audiences, fervent commentators, and opportunistic political candidates. Brexit, the border wall, and their attendant chaos are all merely symptoms. Politicians infantilize their audiences when they spoon-feed them placations while palming stiffer tonics, such as the externalities of making limited policy in a nation of laws, not men or magic. Ambition is admirable, and transformative policies are often vitally needed. But presenting them as aspirations first and messy, uncertain negotiations second will lead to further reductionism and mercuriality.

Change must begin with voters demanding clarity when candidates peddle in ambiguity, specifically when those candidates wield stump speeches. Politicians remain conscious of the bases that elected them and the many expectations on their shoulders. Thus, voters, as the indispensable electoral energy, must begin to unravel the paradigm. Too often, Americans do not live up to their own rhetoric; 72 percent of Americans think that the two parties not cooperating would harm the nation “a lot.” Yet when faced with negotiations over pressing national issues, most partisans want their party to get more out of a deal, blame the other party for political incivility, and increasingly view the other side as a threat.

Americans must resolve their civic schizophrenia. They must unlearn compromise as a dirty word and lower the bludgeons of ideological warfare. Political nuance is tossed aside when a rabid base seeks only partisan victory; honest rhetoric and legislation soon follow. They must dismantle the system of benefits that propels candidates towards ideological absolutism and subsequent hyperbole on the campaign trail. Finally, they must redouble their commitment to the twin institutions identified by experts as crucial to holding politicians accountable: robust elections and an informed voting populous.

So long as voters don’t require candidates to truthfully acknowledge their potential political limits within a bicameral system of checks and balances, policy promises will continue to balloon and unmoor. So long as the media figures retaining attention by enforcing party purity are venerated, parties will cling to the obtuse policies popular with their bases at the debasement of bipartisanship. So long as politics are treated one way on the trail and one way in the chamber, both spheres will suffer.