Former House speaker Newt Gingrich (R-Ga.) on the "Fox & Friends" TV program. Gingrich is a devotee — and author — of alternative histories. (Richard Drew/AP)
Gavriel Rosenfeld is professor of history at Fairfield University and the author of several books on counterfactual history, including "The Fourth Reich: The Specter of Nazism Since World War II."

There has never been a better time than the present to speculate about the past. Just turn on your TV — or flip open your laptop — and the evidence is unmistakable: alternate history shows are everywhere.

Leading the pack are counterfactual Nazis. Amazon Prime’s hit series, “The Man in the High Castle,” now concluding its third season, features a Nazi-ruled United States. The recent BBC series “SS-GB” portrays life in Nazi-occupied Britain. And coming soon are HBO’s dramatization of Philip Roth’s novel, “The Plot Against America,” about a fascist United States under President Charles Lindbergh, and Amazon Prime’s series, “The Hunt,” about the effort of fugitive Nazis in 1970s-era New York to establish a Fourth Reich.

Nor are alternate histories just on TV. Critically acclaimed novels have explored diverse what-ifs, including Ben Winters’s “Underground Airlines” and Nava Semel’s “Isra Isle,” about a Jewish state being founded in Upstate New York. Academics have gotten in on the fun, too, exploring the consequences of Charles Darwin never being born, Archduke Franz Ferdinand not being killed in 1914 and the Bolshevik Revolution ending in failure.

What explains the wave of what-ifs in American popular culture?

Technological trends are partly responsible. The Internet revolution, by creating the digital infrastructure for supporting limitless, bingeable streaming content, has created an unprecedented demand for shows that can attract and retain viewers’ attention. This development has produced not only what commentators have called a “new golden age of television” but also a golden age of alternate history by providing the big-budget support necessary for shows about what-ifs to break into the cultural mainstream.

But the primary driver of the present-day popularity of what-if thinking reflects our world’s deepening sense of crisis. Alternate history flourishes in periods of rapid change and uncertainty. Counterfactual speculation dates back to antiquity, when historians such as Herodotus and Thucydides used it in response to the Persian and Peloponnesian wars. It continued through the Middle Ages, when chroniclers such as Geoffrey of Villehardouin and William of Tyre imagined alternate outcomes to the Crusades. And it evolved further in the modern era, in the efforts of 19th-century French writers, such as Charles Renouvier and Jules Michelet, to wrestle with the counterfactual consequences of the French Revolution and Napoleonic Wars.

Their works, like countless other alternate histories, responded to the upheavals of their day. They gave voice to the conviction that history is an open-ended — rather than a predetermined — process; one rooted in unforeseen contingencies instead of predictable forces. They expressed competing views of their eras’ events, fantasizing how history could have been better and mulling nightmares about how it might have turned out worse. And they offered political commentaries, both liberal and conservative, about the links between past and present.

All of these traits help explain why what-ifs proliferate in periods of political turmoil like the one we’re living through now. In the past decade, the Western world, especially the United States, has been buffeted by tumultuous events: the global financial crisis, concerns about immigration, the upsurge in right-wing populism, anxieties over climate change. These developments have compounded preexisting fears about international threats — Islamic terrorism, competition from China and malfeasance from Russia — and sharpened people’s insecurity about the present and future. Because people intuitively grasp that volatile periods of rapid change are shaped by unforeseen contingencies, they become sensitive to the ways in which key “points of divergence” can easily swing events in one direction or another.

This insecurity about the present has shaped how people have reimagined the past.

Many present-day fears have found expression in counterfactual nightmares. Perhaps the most potent is the fear of right-wing radicalism. “The Man in the High Castle” has been such a success partly because its counterfactual premise — of an America ruled by Nazis and homegrown collaborators — channels liberal anxieties about the country’s right-wing turn under President Trump. The same can be said of Ben Winters’s “Underground Airlines,” whose grim portrait of slavery’s persistence in a present-day Confederacy indicts the endurance of racism in post-Charlottesville America. In a different context, the dystopian depiction of an isolationist, authoritarian Poland in Netflix’s “1983” can be interpreted as an allegorical critique of Poland’s current Law and Justice government under Jaroslaw Kaczynski.

But it’s not just the dystopias that reflect present-day anxieties. Nava Semel’s “Isra Isle” reflects the wishful thinking that typifies counterfactual fantasies. By imagining a Jewish state founded in North America instead of the Middle East, the novel averts the eruption of the Arab-Israeli conflict. Other works propose fantasies only to undermine their credibility. Hulu’s “11.22.63” throws cold water on the notion that preventing President John F. Kennedy’s assassination would have improved the course of American history, by showing (courtesy of a time-traveling James Franco) how his survival unleashes a nuclear catastrophe upon the United States. The same is true of Christopher Brown’s novel, “Tropic of Kansas,” in which Ronald Reagan’s assassination in 1981 backfires in similar fashion. Even fantasy devolves into a caution against hoping that things could be better.

In playing with the past’s historicity, alternate histories have often sparked controversy. When HBO announced last year that they were pursuing a new project called “Confederate,” to be set in a world in which the South won the Civil War, some African American critics angrily charged that such a show, created by white producers, would glorify the Confederacy and minimize black suffering. HBO pushed back, insisting that the premise would be developed as a nightmare scenario, but the episode revealed how counterfactual portrayals of sensitive topics can foster misunderstandings.

It is no surprise, then, that alternate history has often been dismissed as a wholly political, and thus intellectually unserious, enterprise. The sloppy use of counterfactual reasoning by unpopular conservative figures such as Trump (who in 2017 implausibly claimed that if “Andrew Jackson [had] been a little later, you wouldn’t have had the Civil War”) explains why liberal critics such as John Heilemann have tried to discredit alternate history by associating it with conservative firebrand Newt Gingrich, who has penned several counterfactual novels and currently hosts a video series on Facebook series called “What If: History That Could’ve Been.”

The adjective “alternate” in alternate history further underscores the genre’s larger problem. At a time when many Americans worry about the spread of “alternative facts,” alternative history seems like another post-truth concept. Works based on counterfactual reasoning seem risky in an era when facts themselves appear to be under threat.

These problems notwithstanding, we should welcome that alternate history narratives will probably proliferate in the future. Critics may complain that our penchant for wondering “what if?” stems from our era’s uncertainty. But we should recognize that the same counterfactual mind-set produced by our turbulent world can help us cope with it by altering our perspective in such a way as to understand the dynamics of rapid change.

By revealing the complex relationship between determinism and chance in shaping historical events, alternate histories can help us understand the forces that will influence our future. Perhaps most important, by making clear that history’s course is not inevitable, what-if narratives remind us that we all retain the free will to choose responsibly and act morally and decisively as agents of historical change.