In the 20th century, constructive doomsaying helped prevent the Cold War from becoming a shooting war. It was ultimately worst-case thinking that stabilized nuclear deterrence and staved off nuclear Armageddon. Herman Kahn’s clinical projections of nuclear devastation dazzled and horrified a growing audience — his warnings began with a series of Princeton lectures and eventually became the basis of his best seller “Thinking About the Unthinkable.” The eventual Nobel Prize-winning economist Thomas C. Schelling used game theory to explore the risk that conventional conflict could escalate to the use of nuclear weapons; his work demonstrated the value of arms control and helped establish nuclear deterrence based, however perversely, on mutual assured destruction.In the 1980s, Jonathan Schell’s series of New Yorker essays (and subsequent book), “The Fate of the Earth,” reinvigorated popular alarm about nuclear war and stimulated calls for nuclear disarmament on both sides of the Atlantic. In line with dystopic novels like “On the Beach” by Nevil Shute and movies like “Fail-Safe,” “Dr. Strangelove,” “The Bedford Incident” and “The Day After,” worst-case thinking kept the prospect of nuclear holocaust real and the need to avoid it urgent. Clearly it influenced Ronald Reagan and Mikhail Gorbachev, who seriously contemplated nuclear disarmament in 1986.This urgent brand of collective cultural alertness receded after the Cold War. On the left, worst-casing thinking was blamed for the expansive growth of nuclear arsenals and the ill-fated U.S. war in Vietnam. Now the Republican Party’s embrace of “alternative facts,” aided by the growth of conservative media, has effectively created a separate domestic reality for millions of Americans. Since Jan. 6, 2021, comedians, partisan journalists and public intellectuals have recognized, ridiculed and lamented the state of our democracy and raised the possibility of a “slow-moving coup” (Bill Maher) or a “worst-case scenario” for our politics (Robert Crawford in The Nation). Other columnists and historians (Chauncey DeVega and Max Hastings, for example) have casually mooted the possibility of secession or large-scale political violence in the wake of the 2024 presidential election. A few recent books, like the political scientist Barbara F. Walter’s “How Civil Wars Start” and the journalist Stephen Marche’s “The Next Civil War,” have been discussed.But systematic and dispassionate analysis of such possibilities has not widely emerged. In June 2020, the bipartisan Transition Integrity Project — comprising over 100 former and serving government officials, academics, research analysts, journalists and other experts — held tabletop exercises on four different 2020 election crisis scenarios. Selected teams hypothesized moves and countermoves, responses and counter-responses, and in August 2020 published a broadly prescient report — which suggested that the election could be contested into 2021 and the transition process disrupted. It also included several preventive measures with an eye to 2024-25. Perhaps understandably, given the political climate, most participants were reluctant to identify themselves publicly and only a few talked to the media about the exercise. Two conservative outfits, the Texas Public Policy Foundation and the Claremont Institute, jointly gamed out similar scenarios, concluding that the constitutional order would hold. But these projects were short term and situationally limited and have not generated sustained open-source consideration of the more dire possibilities that have surfaced since Jan. 6.Predictably, far-right groups mobilized to dismiss the Transition Integrity Project’s activities as leftist “psychological warfare,” and some branded it a blueprint for a left-wing coup. That should not stop a reprise of the project’s efforts with respect to the 2024 election. In light of the lack of contingency planning for major violence on Jan. 6 by the Capitol Police and the Department of Homeland Security, such planning is presumably underway at federal law-enforcement agencies and the Pentagon. But that’s not enough.