It’s not often I run across political science that genuinely changes my understanding of how American politics works. But Frances Lee’s research has done exactly that. Twice. Not that he asked me, but if President Donald Trump were looking for a political scientist to read to gain a more strategic perspective on his current predicament, I’d direct him to Lee.

Lee’s research reverses the conventional wisdom on two forces that we’ve long believed make American politics run more smoothly: political competition and presidential leadership. The conventional wisdom holds that close competition ensures voters have real choices and politicians face real accountability and strong presidential leadership injects a necessary energy into the system. Lee challenges both views, presenting new evidence suggesting that both forces intensify, and perhaps even drive, the kind of all-out partisan combat that is paralyzing the system.

The current government shutdown is Lee’s thesis in action. To understand how we got here — and why American politics finds itself more and more frequently in crises like this one — you need to understand her work.

Our era of political hyper-competition is an aberration

Let’s start with political competition. In her new book Insecure Majorities, Lee argues that this era of close competitiveness, in which the parties are constantly losing and regaining congressional majorities and White House control, is an aberration. For most of American history, one party or the other has been comfortably dominant. The Republican Party ran American politics for most of the late 19th and early 20th centuries. Democrats were dominant in the post-Depression era.

Consider this chart Lee makes, which combines share of the national two-party presidential vote, share of House seats, and share of Senate seats. The higher the line stretches upward, the larger Democrats’ advantage. The further it plunges downward, the stronger the GOP’s lock on political power.

Frances Lee, Insecure Majorities

The stability of party control in America’s past is easy to miss because our political histories tend to be presidential histories, and the presidency has tended to be more competitive than control of Congress. But our era is an aberration. In this 150-year timeframe, there’s no period where political control has been as tenuous as in the last four decades.

It’s very hard to say why this is. Shouldn’t politics typically be competitive, with the losing party making the ideological and strategic adjustments necessary to win back power? And why are presidential landslides so much less common in the modern era than in our past?

I posed this question to a number of political scientists, including Lee, and none had a good answer. It’s easy enough to see that parties won more political power, and held it for far longer, in the past than in the present. Why it is that American politics became more competitive around 1980 and has remained that way since stumps everyone I’ve asked.

Much clearer, however, is the effect that heightened political competition is having on American politics.

How one-party dominance leads to more cooperation

Lee’s argument is that close competition, where “neither party perceives itself as a permanent majority or permanent minority,” breeds all-out partisan combat.

When one party is perpetually dominant, the subordinate party has reason to cooperate, as that’s the only realistic shot at wielding power. Either you work well with the majority party or you have no say over policy, nothing to bring home to your constituents.

You can think of a politician’s political priorities as running roughly in this order:

Win reelection. Win the majority. Influence governance as much as possible.

Governing comes third not because politicians are cynical, though they often are, but because you can’t govern at all if you don’t win reelection, and you can’t govern effectively from the minority. Even so, if winning the majority becomes impossible, then the priorities look like this:

Win reelection. Influence governance as much as possible.

Indeed, in this ranking, priorities one and two work together because you’re likelier to win reelection, at least in past eras in American politics, if you’re bringing money home to your district and can brag about bills with your imprint on them. But for those priorities to work together, you have to cultivate a very good relationship with the majority party. You can’t be engaged in an all-out effort of obstruction and sabotage.

But when winning the majority becomes possible, the logic of that cooperation dissolves. If you’re signing on to the majority’s bills, and bragging about the provisions you added to their legislation, then you’re part of their reelection strategy. If you’re keeping the majority from passing anything, and making sure people are fed up with the state of Washington, then the voters are likelier to make a change.

This is the paradox of bipartisanship: What Bob Michel, the leader of the House Republicans in the 1980s, called the “subservient, timid mentality of the permanent minority” makes it easier to work with the majority but harder to win back the majority.

Once a political party has decided the path to governing is winning back the majority, not working with the existing majority, the incentives transform. Instead of cultivating a good relationship with your colleagues across the aisle, you need to destroy them, because you need to convince the voters to destroy them, too.

Dick Cheney, then a member of the House of Representatives, put it sharply in 1985. “Confrontation fits our strategy,” he said. “Polarization often has very beneficial results. If everything is handled through compromise and conciliation, if there are no real issues dividing us from the Democrats, why should the country change and make us the majority?”

There’s nothing particularly unusual about this. It’s the logic of zero-sum contests everywhere. But America’s political system is unusual in that it fosters divided government and is full of tricks minorities can use to obstruct governance, like the filibuster. The current shutdown, for instance, reflects the fact that the Republican president needed Democratic votes to fund the government, even when Republicans held the majority in both the House and the Senate.

Chip Somodevilla/Getty Images

Imagine this structure outside the context of American politics. Imagine you worked in an office where your boss, who was kind of a jerk, needed your help to finish his projects. If you helped him, he’d keep his job and maybe even get a promotion. If you refused to help him, you’d become his boss, and he might even get fired. Now add in a deep dose of disagreement — you hate his projects and think they’re bad for the company, and even the world — and a bunch of colleagues who also hate your boss and will be mad at you if you help him.

That’s basically American politics right now. Bipartisan cooperation is often necessary for governance, but irrational for the minority party to engage in.

Lee’s argument is that this bizarre structure worked during much of American history because one party was usually dominant enough to make cooperation worth it for the minority. But that hasn’t been true for almost 40 years now, and the seemingly endless — and ever-escalating — procession of shutdowns, debt ceiling crises, and assorted other political showdowns is the result.

Reading Lee’s book — and talking to her on my podcast — I found myself thinking of something both very different from, and very similar to, American politics. In his wonderful look at the biology of stress, Why Zebras Don’t Get Ulcers, primatologist and neuroscientist Robert Sapolsky writes that in most social hierarchies, in most times, stress accumulates among the weak and downtrodden members of the tribe. But there’s an exception:

Suppose you keep the dominance system unstable by shifting the monkeys into new groups every month, so that all the animals are perpetually in the tense, uncertain stage of figuring out where they stand with respect to everyone else. Under those circumstances, it is generally the animals precariously holding on to their places at the top of the shifting dominance hierarchy who do the most fighting and show the most behavioral and hormonal indices of stress.

The less stable the system, the more stress, conflict, fear, and even brutality it’s likely to elicit, because animals — and we are animals — fight very hard to get on top or stay there.

American politics is now an unstable system, and that’s even truer given Trump’s persistent unpopularity. In creating this shutdown, Trump thought he could force Democrats to cooperate with him by sharpening the contradictions between the parties and spiking voters’ anger at Washington. In doing, he took the strategy ambitious minorities usually deploy against the majority and unleashed it on himself, giving Democrats the benefits of conflict without the cost of being blamed for causing it.

It was a staggering miscalculation.

President Donald Trump meets with Congressional Leadership on December 7.

Olivier Douliery-Pool/Getty Images

What Trump would do if he really wanted his wall

Trump’s actions here likely reflect another misunderstanding of how American politics works, one that Lee tackled in an earlier book.

The media tends to tell the story of American politics as if it were an episode of The West Wing. The protagonist is the president, and any problem can be solved with enough presidential leadership, with a soaring enough presidential speech.

Brendan Nyhan, a University of Michigan political scientist, calls this the Green Lantern Theory of the Presidency, and defines it as “the belief that the president can achieve any political or policy objective if only he tries hard enough or uses the right tactics.” In other words, the American president is functionally all-powerful, and whenever he can’t get something done, it’s because he’s not trying hard enough, not leading aggressively enough.

Trump, whose political history prior to winning the presidency included a lot of speeches and television appearances but no actual governance, seems particularly besotted by this vision of politics. He often seems to understand his presidency as the Donald Trump Show, where he is the main character, perhaps the only character. During his party nomination speech, Trump famously said, “I alone can fix it,” and if the actual experience of the presidency has perhaps tempered that view a bit, it hasn’t tempered it enough for Trump to work in a truly collaborative, consistent way with the other parts of the government.

In her book Beyond Ideology, Lee shows that this view of the presidency isn’t just wrong; it’s often the very cause of presidential failure. Presidents don’t have the power to pass, or even write, legislation. As Richard Neustadt famously put it, “presidential power is the power to persuade.” The problem is presidents are often anti-persuasive, particularly in times of divided government.

This was a lesson Barack Obama learned the hard way. He too was deeply convinced of his persuasive power, only to find it failing, and even backfiring, once Republicans took Congress. But unlike Trump, Obama was alert to changes in political incentives, and he began to change his strategy in response. And so Obama, during a period of divided government, learned to stop making himself the face of the bills he actually thought might pass. My colleague Matt Yglesias, in a post that also leans on Lee’s research, offers a good example:

The landmark Every Student Succeeds Act that passed Congress in late 2015, for example, obviously wouldn’t have passed unless it incorporated a lot of education policy ideas that the Obama administration was on board with. But it was put together quietly, by negotiators from both parties, without a lot of presidential tweets and speechmaking. The downside of this, from Obama’s point of view, was that signing it doesn’t count in the public imagination as an Obama achievement or a major win for his administration. But precisely because it didn’t count as a big “win” for Obama, congressional Republicans could sign on to it.

The “Gang of Eight” immigration bill that passed the Senate in 2013 is another good case study. Obama supported that bill, but he consciously let a bipartisan group of senators take the lead — and thus the credit — because he realized that was the only way Republicans might back the legislation. The bill ultimately died in the House, but it wouldn’t have even gotten that far if it had been Obama’s immigration proposal, rather than Marco Rubio and Chuck Schumer and John McCain and Dick Durbin’s immigration proposal.

The calculus here is simple, and it roughly matches the competitive dynamics we discussed earlier. In day-to-day political bargaining, the president acts as the leader of one political party and the central antagonist of the other. When Mitch McConnell said “the single most important thing we want to achieve is for President Obama to be a one-term president,” he was, as he often does, simply stating the obvious in uncommonly stark language. Does anyone doubt that, right now, the central objective of the Democratic Party is removing Trump from office?

Even putting aside the deep ideological disagreements that divide the parties, when the president stakes his reputation on a political fight, in a zero-sum political system, an ambitious minority party almost has to oppose him. To join him would mean joining his reelection campaign, and putting their own jobs, not to mention their chances of regaining the White House, at risk. But if the president is willing to set aside scoring points, as Obama did in 2013 and 2015, the calculus can shift, at least a bit.

When presidential leadership backfires

This doesn’t mean presidential leadership is never helpful. It often is — if your party holds congressional power. The key to understanding the powers and limits of presidential persuasion, Lee writes, is that presidential leadership “tends to increase cohesion within both major parties and to exacerbate conflict between them.” That is to say, the president taking a position on an issue tends to rally his own side to the cause and polarize the other side against it.

Lee shows this in a novel way. Using a data set of congressional votes on issues that have no clear ideological content, she shows that if a president takes a position on those issues, the chances of a party-line vote skyrockets. Indeed, whether an issue gets onto the president’s agenda is “one of the best predictors of the overall level of partisanship, with party polarization increasing by fully 34 percent when presidents highlight them in their State of the Union addresses.”

President Trump addresses the nation on border security from the Oval Office.

Carlos Barria-Pool/Getty Images

The implication is that if Trump truly wanted his wall — which was always going to be difficult with a Democratic House that opposes it on both ideological and electoral grounds — he should’ve gone about it quietly, trying to work out a deal behind closed doors that both sides could present as a win.

That’s the crucial thing: Presidents who want to get big legislation done amid divided government have to do everything in their power to avoid making that outcome a win for them, and a loss for the other side. It’s an emotionally unsatisfying form of leadership, but if you care more about the policy than the winning, it’s your best bet.

But Trump cares about the winning. So he’s escalated and escalated, focusing the entire country’s attention on the issue, staking his reputation on winning the shutdown fight and the funding for the project. There’s literally no strategy he could’ve chosen that would’ve made Democratic support for the wall less likely.

Of course, if you believe, as I do, that Trump never really wanted the wall — that he just wants a fight that will fire up his base — his strategy has always made perfect sense. But if he does want the wall, or anything else during the next two years of his presidency, he may want to brush up on Lee’s work and change his strategy. If I might suggest a place to begin, my podcast conversation with Lee is a good introduction to her ideas.

Correction 1/24: An earlier version of this piece misstated Brendan Nyhan’s current academic affiliation. He is now with the University of Michigan.