President Obama (Jonathan Ernst/Reuters)

Each week, In Theory takes on a big idea in the news and explores it from a range of perspectives. This week, we’re talking about polarization in politics. Need a primer? Catch up here.

Dana Nelson is the Gertrude Conaway Vanderbilt chair of English and American studies at Vanderbilt University. She is author of “Bad for Democracy: How the Presidency Undermines the Power of the People” and, most recently, “Commons Democracy: Reading the Politics of Participation in the Early United States.”

Our nation’s Framers got a lot right, but they got something major wrong: They assumed that the three branches of our government would remain co-equal, maintaining the Constitution’s delicate balance. The branches do not have the same structural ability to protect their powers, and, over time, the executive has become the dominant branch. This constitutional unbalancing contributes mightily to the political polarization of the nation’s electorate.

When the Framers drafted the Constitution in 1787, they aimed to create a strong executive to replace the weaker leadership structure that the Articles of Confederation had provided, and to counter state governments that deliberately devised weak governors. Nevertheless, they denominated Congress as the “first” and most important branch of government. The Framers expected that the president would occasionally check the democratic enthusiasm of Congress as part of his mission to uphold the Constitution and execute the law, but they attempted to ensure that the work of democracy would happen mainly through the legislative work of that first branch. They gave us, in other words, a congressional government.

Yet over time, as experts approvingly concede, the president has become the main agent within U.S. democracy. Presidential government replaced congressional government over the course of the 20th century. This is no simple shift in the Constitution’s architecture — it’s an unbalancing of the Framers’ design and a hard one to stop. The executive office accrues unprecedented, unconstitutional powers with each new president. As individuals, they are hardly to blame. They are doing their job, faithfully executing the growing powers of the office.

Because observers mostly like it when the president takes command (he or she looks like a leader; we feel protected), the ramifications of this constitutional unbalancing have remained largely unexplored. One ramification — polarization — has long been a feature of U.S. politics, but the increasing powers of the unitary, unilateralist president both with regard to national security and domestic policy have upped the ante: There’s ever more power at stake.

The president’s increasing supremacy means that pundits and intellectuals, party officials and citizens on both sides of the political divide now proceed as though politics is war by other means, when the reverse used to be a truism. Their effort to destroy the other side’s fighting ability and secure the presidency for their party contributes to what historian Garry Wills described as the militarization of our political culture, in which citizens are routinely asked to recognize the elected president as “our” and not just the military’s “commander in chief,” putting routine politics on a wartime basis. It is precisely this ethos that encourages presidential candidate Hillary Clinton to rank Republicans alongside Iranians as enemies she is proud to have made — and to draw the loudest applause of the evening at the first Democratic presidential candidate debate in October 2015.

Concluding that those who disagree with you is the enemy is bad for democracy. A commitment to democracy means pledging to the continued negotiation — and even the cultivation — of political disagreement, which is irrefutably good for democratic decision-making. Studies repeatedly confirm that from strong differences of opinion come sounder and more effective decisions than those made by people in agreement. Disagreement is not democracy’s problem: It is its strength. The big question is what we do with and about our disagreements.

Democracy is not a winner-take-all game. Quite differently, it’s an ethic demanding that participation is not just for the people whose views you like but also for ones whose views you despise. The downward spiral of presidential unilateralism pulls us ever further away from being able to remember that democratic power is what we the people delegate to the president, not what he wins for us.

To the extent that we forget, we lose the radical promise of democratic self-governance that mobilized this nation’s revolutionary resistance to the British monarchy. Instead, we comfort ourselves by electing the king who makes us feel safest, letting him use the authority of our power for his increasingly sovereign, secret and unchallengeable aims. By yielding to polarized unilateralism and taking this comfort, we dim the democratic experiment.

No president will ever reverse this course for us, even though most candidates promise to do so. If we’re going to do anything about the many negative trends associated with the increasing political power of the presidency, we need to stop expecting the next president to fix things. We need to look elsewhere — reevaluating our intolerances and reinvesting in the face-to-face, deliberative work of democracy, both locally and in Congress — for the solutions that can navigate us back toward something that genuinely rests on, safeguards and cultivates democracy.

Explore these other perspectives:

David Broockman: How well-meaning political reformers are helping to elect President Trump

Thomas E. Mann and Norman J. Ornstein: Republicans created dysfunction. Now they’re paying for it.

Jim Marshall: Congress could reduce polarization. It has chosen not to.

Thomas Petri: Our government is messy — but that doesn’t mean it isn’t working

Alan I. Abramowitz: America today is two different countries. They don’t get along.

Jane Mansbridge: Three reasons political polarization is here to stay