I would encourage readers to start with the Preface. There they will find a concise summary of the intellectual journey that prompted me to write Isolationism and of the book’s aims. “My main objective in writing this book is to provide readers a go-to volume for understanding American isolationism. I aim, in accessible fashion, to tell the story of America’s efforts to shield itself from the world—from the founding era through the Trump presidency” (page xiv). Much of the book looks back at the nation’s history, but I also use that history to explore the present and future: “America’s isolationist past does have much to teach us about the nation’s current geopolitical predicament” (page xii). I would also encourage readers to skim pages 8-28. This section provides an overview of book’s main arguments and the flow of the historical narrative.Finally, I would urge that readers jump into one of many historical turning points explored in the book—such as the account of the anti-imperialist backlash against the Spanish-America War of 1898 (pages 197-205). When President William McKinley launched a war to expel Spain from Cuba, he claimed he was acting “in the cause of humanity.” The U.S. Navy handily defeated the Spanish fleet in the Caribbean and Pacific, and proceeded to wrest control of Cuba, Puerto Rico, Hawaii, the Philippines, Guam, Samoa, and the Wake Islands. McKinley called the annexation of Hawaii “manifest destiny” and portrayed the military occupation of the Philippines as a “holy cause,” explaining that “there was nothing left for us to do but to take them all, and to educate the Filipinos, and uplift and civilize and Christianize them.”Many Americans didn’t buy it—especially after a bloody insurgency broke out in the Philippines that took the lives of some 4,000 U.S. soldiers and hundreds of thousands of Filipinos. William Jennings Bryan, who ran against McKinley in the 1900 election, claimed that the nation could not “endure half republic and half colony—half free and half vassal.” William Sumner, an influential Yale professor, offered a similar critique: “Expansionism and imperialism (...) appeal to national vanity and national cupidity. They are seductive (...). They are delusions, and they will lead us to ruin unless we are hard-headed enough to resist them.”McKinley won the 1900 election and the United States kept hold of the territories it seized in 1898. But enthusiasm for further territorial expansion evaporated, and the backlash against foreign entanglement helped clear the way for the isolationist retreat of the interwar era. The debate over American foreign policy spawned by the Spanish-American War profoundly resonates with the debates taking place today over the nature of America’s role in the world.I hope that Isolationism leavens the global conversation that needs to take place about the nature of U.S. statecraft moving forward. Given the outsized role that the United States plays in global affairs, Americans as well as many other peoples affected by U.S. policy need a better understanding of America’s role in the world across the longue durée of the nation’s history. And we need to learn the right lessons from that history, drawing on both isolationist and internationalist traditions to find a sustainable brand of statecraft that constitutes the middle road between overreach and underreach.I lay out a strategy of “judicious retrenchment” as a means of arriving at that middle road. I hope that the book and the debate it provokes help build intellectual and political support for this strategy. Judicious retrenchment entails ending the forever wars in the Middle East and pulling back from the region militarily—while maintaining America’s main strategic commitments in Europe and the Asia Pacific. The United States continues to have an overriding interest in managing great-power competition in Eurasia. Russia and China both pose expansionist threats to their neighbors, which means that the same objective that guided U.S. strategy during World War II and the Cold War—preventing the domination of Eurasia by a hostile power—still applies.Less reliance on wars means more reliance on diplomacy. Judicious retrenchment entails restoring America’s role as a team player that works with other nations. Only through joint international action can we effectively address the paramount challenges of our time, including managing a globalized and interdependent economy, arresting climate change, shutting down terrorist networks, countering nuclear proliferation, promoting cybersecurity, and advancing public health. Such joint action will often require U.S. leadership to get off the ground.And judicious retrenchment entails reclaiming America’s exceptionalist calling as a beacon of democracy. Nonetheless, the United States must return to its original conception of exceptionalism and seek to spread its republican experiment by example rather than by more forceful means. Knocking off unsavory regimes usually causes more harm than good. Russian and Iranian influence may be increasing in the Middle East as the United States pulls back from the region. But it is Washington’s foolhardy penchant for toppling regimes, not its self-restraint, that is the root cause of the inroads being made by Moscow and Tehran.Reclaiming the nation’s original conception of exceptionalism requires more than exercising restraint and coming to terms with the reality that the United States cannot solve all the world’s problems. It also requires putting America’s own house in order. The United States cannot serve as a model for other nations when its political landscape is so deeply polarized and its institutions so dysfunctional. The first priority is to tackle the sources of the nation’s political ills, including the pandemic, inequality, racial injustice, and the profound sense of economic insecurity that pervades much of the electorate.Exceptionalism is inseparable from the American creed. And with illiberalism and intolerance on the march globally, the world urgently needs an anchor of republican and pluralist ideals—a role that only the United States has the power and credentials to fulfill. But the exceptionalist narrative has for way too long been an excuse for doing too much abroad. Given the dilapidated state of the American experiment, the renewal of the nation’s unique calling must start at home.