Political analysts, scholars and close observers of government are explicitly raising the possibility that the polarized American electoral system has come to the point at which a return to traditional democratic norms will be extremely difficult, if not impossible.The endangered state of American politics is the dominant theme of eight articles published by the National Academy of Sciences on Tuesday, with titles like “Polarization and tipping points” and “Inter-individual cooperation mediated by partisanship complicates Madison’s cure for ‘mischiefs of faction.’ ”The academy is not alone. On Dec. 6, The Atlantic released “Trump’s Next Coup Has Already Begun,” by Barton Gellman, and “Are We Doomed? To head off the next insurrection, we’ll need to practice envisioning the worst,” by George Packer.On Dec. 10, The Washington Post published “18 Steps to a Democratic Breakdown” which warned:Democracy is most likely to break down through a series of incremental actions that cumulatively undermine the electoral process, resulting in a presidential election that produces an outcome clearly at odds with the voters’ will. It is this comparatively quiet but steady subversion, rather than a violent coup or insurrection against a sitting president, that Americans today have to fear most.Michael W. Macy, a professor of sociology at Cornell and the lead author of “Polarization and tipping points,” put it this way in an email:Unlike the threat to democracy posed by a military coup, the threat posed by authoritarian populism is incremental. If the water temperature increases only one degree per hour it may take a while before you notice it is too hot and by that time it is too late. We might be better off if we faced an armed insurrection, which might be the exo-shock needed to get the G.O.P. establishment to wake up.The political scientist Suzanne Mettler, also at Cornell, used the same metaphor of slowly boiling water in her reply to my query:The greatest danger to democracy right now has emerged in one of our two major parties — a longstanding party that helped to protect democracy until recently, and this makes it hard for people to recognize what is going on. Finally, I think that most Americans now see politics through very partisan lenses and are mostly attentive to how their “team” is doing; they are much less likely to be thinking about the health of the basic pillars of democracy, e.g. electoral integrity, the rule of law, the legitimacy of the opposition, and the integrity of rights. Our political system is in crisis and we should be shouting from the rooftops about it and coming together to save it.Zack Beauchamp, a senior correspondent at Vox, writing on Dec. 9, raised similar concerns: “We are experiencing failures on both the elite and mass public level,” he wrote, as Republican elites “have chosen to normalize the violence committed by their extreme right flank on Jan. 6.”The activist anti-democratic Trump wing of the Republican Party, committed to avoiding at nearly any cost a political system dominated by an Election Day majority of racial and ethnic minorities, women and social and cultural liberals, has adopted an aggressive strategy to preserve the political power of whites, especially heteronormative white Christians.Democracy — meaning equal representation of all citizens and, crucially, majority rule — has, in fact, become the enemy of the contemporary Republican Party. As The Washington Post noted on Jan. 24, “The last two Republicans to win a majority of the popular vote in a presidential contest were father and son: George H.W. Bush in 1988 and George W. Bush in 2004.” In the four elections since 2004, the Republican nominee has consistently lost the popular vote to the Democratic candidate, including Donald Trump in 2016 and 2020.The widely publicized efforts by Republican-controlled state legislatures to politicize election administration and to disenfranchise Democrats through gerrymandering and restrictive voting laws testify to the determination of Republicans — especially the 66 percent who say they believe that the 2020 election was stolen — to wrest control of election machinery. On Sept. 2, ProPublica documented a national movement to take over the Republican Party at the grass roots level in “Election Deniers Organize to Seize Control of the G.O.P. — and Reshape America’s Elections.”These developments, taken together, are amplifying alarms about the viability of contemporary democracy in America.“The nonlinear feedback dynamics of asymmetric political polarization,” a Dec. 14 paper by Naomi Ehrich Leonard and Anastasia Bizyaeva, both at Princeton, Keena Lipsitz at Queens College, Alessio Franci at the Universidad Nacional Autónoma de México and Yphtach Lelkes at the University of Pennsylvania, argues that in the case of polarization, there are:critical thresholds or moments when processes become difficult if not impossible to reverse. Our model suggests that this threshold has been crossed by Republicans in Congress and may very soon be breached by Democrats.I sent the five authors a series of questions asking them to elaborate on a number of points, and they replied in a jointly written email. My first question was: “Could you explain in terms accessible to the layperson how ‘political processes reinforce themselves’ in ways that can push a political party past a ‘tipping point’ ”?Their reply:Political processes, like any other natural dynamical process, in nature, technology, or society, have the capacity to feed themselves and enter an unstable positive, or, self-reinforcing, feedback loop. A classic example is an explosion: when thermal energy is provided to burn a few molecules of a combustible substance, they in turn produce more energy, which burns more molecules, producing more energy in a never-ending loop, at least until combustibles are no longer available.A similar process can take place in politics, they argue:For example, elected officials can respond to the signals of extremist donors by becoming more extreme themselves. When these extremist representatives become party leaders, they are then in a position to punish moderates in their party by backing more extreme candidates in primaries. This in turn leads to the election of more extremist candidates and the cycle continues.In theory, votersare a potential check on this cascading extremism, but they must be willing to punish ideologically extreme legislators by voting them out of office. As voters have become more concerned about party labels than ideology, they have become less willing to do that, allowing cascading extremism to continue.What about the Democratic Party, I asked?The Democrats are indeed still below the tipping point; therefore, their polarization state is still evolving slowly, or, linearly. But looking at the current policy mood trend and projecting our model slightly into the future, the present large left shift in policy mood due to the Trump era could easily cause the Democrats to tune up their ideological self-reinforcing behavior and let them pass their polarizing tipping point.The good news, the five authors continued, “is that the Democratic Party is still very much in control of their trajectory.”Leonard and her co-authors are apprehensive about the future course of the Republican Party:Even if Republican voters suddenly decide to start punishing extremists in their party, so many other parts of the political process — interest groups, right-wing media, donors — encourage and reinforce the extremism that we expect it would have little effect. In fact, Republican leaders would very likely simply stop listening to Republican voters or ignore elections altogether. Indeed, this is already happening.In “Polarization and tipping points” Macy, along with Manqing Ma, Daniel R. Tabin, Jianxi Gao and Boleslaw K. Szymanski, all of Rensselaer Polytechnic Institute, map out the risks of escalating partisan hostility:the existence of a tipping point beyond which the activation of shared interests can no longer bring warring factions together, even in the face of a common threat. Our interest in this problem is motivated by a series of crises that might be expected to activate a broad political identity and unified response: the Great Recession, Russian electoral interference, impending climate catastrophe, a global pandemic, and, most recently, the January 6. attack on the U.S. Congress.As partisanship becomes a core element of voters’ self-identity and as voters adopt policy stands in line with their party, polarization reaches new and threatening heights, Macy and his four co-authors argue. In an email, Macy wrote:The most likely outcome of increasing polarization is political paralysis in which the parties are more interested in preventing the other side from winning than in solving problems. We have heard politicians even feel so emboldened that they can publicly acknowledge that their goal is obstruction, not problem solving. That is the most likely outcome of extreme polarization. A less likely but more frightening outcome is that the partisan animosity against the opposition becomes so intense that each side now views the other as “traitors” or “enemies of the people.” When that happens, the party in power may feel justified in changing the rules of the game to prevent the other party from being able to hold it accountable.An R.P.I. report on the Macy paper quotes Szymanski:We see this very disturbing pattern in which a shock brings people a little bit closer initially, but if polarization is too extreme, eventually the effects of a shared fate are swamped by the existing divisions and people become divided even on the shock issue.“If we reach that point,” Szymanski added, “we cannot unite even in the face of war, climate change, pandemics, or other challenges to the survival of our society.”I asked Szymanski to describe the nature of a tipping point which, once triggered, would preclude reversion to traditional democratic norms. He replied by email:In our democracy, the tipping point is achieved when all discussions on divisive issues are within polarized groups and none across groups, because then neither can differences be resolved, nor can we agree to disagree.In “Inter-individual cooperation mediated by partisanship complicates Madison’s cure for ‘mischiefs of faction’” Mari Kawakatsu, Simon A. Levin and Corina E. Tarnita, all of Princeton, and Yphtach Lelkes of Penn make the case that the core strategy developed by one of the nation’s founders to constrain destructive partisan divisions no longer works. The phrase they refer to in the title of their paper comes from Madison’s famous argument, in Federalist Paper No. 10, that the pluralist character of a country as large and diverse as the United States equips the nation to counter “the mischiefs of faction.”The potential of the majority to exercise tyrannical domination diminishes as “you take in a greater variety of parties and interests,” Madison wrote, making it “less probable that a majority of the whole will have a common motive to invade the rights of other citizens; or if such a common motive exists, it will be more difficult for all who feel it to discover their own strength, and to act in unison with each other.”Kawakatsu and her colleagues argue that, in theory, contemporary trends should favor Madison’s strategy:Potentially driven by increases in educational attainment, the nationalization of politics, and changes to the information environment, the number of issues people care about and consider within the realm of national politics has markedly increased. Despite this trend, and the consequent expectation that an abundance of issues will improve the collective cohesion by decreasing the likelihood of monoliths, polarization is markedly worse.How has this come about?“A potential explanation for this paradox is the decreasing dimensionality of the issue space,” Kawakatsu and her colleagues write. “In other words, although the number of issues may have increased, individuals’ opinions on these issues might be so strongly correlated with their political ideology that, in effect, there are only one or two issue dimensions.” Put another way, members of both parties have increasingly adopted the beliefs and issue stands of their fellow partisans, effectively eliminating crosscutting interests, leaving the only salient division the split between Democrats and Republicans.When partisan bias is extreme, the authors write,individuals become completely closed off to influence from ideologically divergent peers, and the emergent tribalism boosts inter-individual cooperation at the cost of a weakened, polarized collective. This suggests that, in a highly polarized state, there will be an emergent tension between the individual and the collective levels, with little incentive for individuals to reduce the collective polarization.The Kawakatsu article builds on the work of Paul Pierson and Eric Schickler, political scientists at Berkeley, who wrote the 2020 essay “Madison’s Constitution Under Stress: A Developmental Analysis of Political Polarization” and the November 2021 book chapter “Polarization and the Durability of Madisonian Checks and Balances.”In the chapter, Pierson and Schickler write:Our two-party system has been grounded in a structural decentralization of political authority. Yet the emergence of hyper-partisanship means that the check on authoritarian developments in the presidency that the Madisonian system relies on most, Congress, may not work. Instead, G.O.P. members of Congress in particular face multiple incentives to bandwagon rather than resist. Among those incentives are the intense preferences of the party’s interest groups, the heavily ‘red’ and negatively partisan electoral bases of these politicians, and the likelihood that influential partisan media will exact a very high price for defection.Given these realities, Pierson and Schickler continue,the developmental perspective we offer raises a disturbing prospect: Under conditions of hyperpolarization, with the associated shifts in meso-institutional arrangements and the growth of tribalism, the Madisonian institutions of the United States may make it more vulnerable to democratic backsliding than many other wealthy democracies would be.In an email, Pierson wrote:Today, polarization has become self-reinforcing. Most of that decentralization is gone — state parties are more linked to national parties; so are many very powerful interest groups; so is the media (especially for the GOP). Everything gets fed into the existing lines of division rather than producing something crosscutting. Defection from one’s party ‘team’ becomes harder to contemplate because victory for the team has become so important, and defection is more likely to result in swift retribution. There is nothing in the system “pulling things back to the middle” or disrupting lines of division. This situation is truly novel for the United States (although there are some parallels to the 1850s, when politics became nationalized around a single issue divide). It is in a very real sense a new and quite different political system.An Aug. 3-Sept.7, CNN survey of 2,119 people demonstrates the differing ways Democrats and Republicans are responding to the emerging threats to democracy.Far higher percentages of Republicans, many of them preoccupied by racial and tribal anxiety, believe “American democracy is under attack” (75 percent agree, 22 percent disagree) than Democrats (46 percent agree, 48 percent disagree). Republicans are also somewhat more likely to believe (57-43) than Democrats (49-51) “that, in the next few years, some elected officials will successfully overturn the results of an election in the United States because their party did not win.”This level of anxiety is in and of itself dangerous, all the more so when it masks the true aim of America’s contemporary right-wing movement, the restoration and preservation of white hegemony. It is not beyond imagining that Republicans could be prepared, fueled by a mix of fear and provocation, to push the nation over the brink.The Times is committed to publishing a diversity of letters to the editor. We’d like to hear what you think about this or any of our articles. Here are some tips. And here’s our email: letters@nytimes.com.Follow The New York Times Opinion section on Facebook, Twitter (@NYTopinion) and Instagram. More