According to Daniel Johnson, Europe is in grave trouble. These days, few would disagree. To the many longstanding and unsolved problems facing the continent over the last decades, several new ones have recently been added: the economic disaster in Greece and similar economic straits elsewhere, the mass invasion of refugees from the Middle East and Africa, and the looming prospect of a British exit (“Brexit,” for short). Among the latest books about the condition of Europe, none bears the confident title of Mark Leonard’s Why Europe will Run the 21st Century, published only a short decade ago.

Does Europe have a future? That’s the question Johnson asks, and it’s the right question. But there are other questions, one of which is whether today’s crisis came as a total surprise or whether unmistakable warning signs existed that were systematically ignored or denied. This is not a matter of historical interest alone; there might well be lessons to be gleaned for, yes, the future of Europe.

On one historical issue there is general agreement: Europe’s recovery after World War II was a great success story. But at a certain stage, progress became fitful and then ground to a halt. This had to do in part with economics, but an even more important factor, according to many thoughtful observers, was political: namely, the unwillingness of individual nation-states to surrender their prerogatives and agree on a common European policy not just in the economic realm but in foreign affairs, defense, and energy. The founding of the European Union in 1993 was designed to overcome these stubborn divisions by means of a continent-wide project conceived for the good of all.

From the beginning, that project had its skeptics. One of them was the late Tony Judt, a professor of European history at New York University whose A Grand Illusion? (1996) assessed the European project as an artificial construct based on unsubstantiated theories and unlikely to succeed. At the time, the book was reviewed in Foreign Affairs by the historian and political philosopher Stanley Hoffmann, the founding director of Harvard’s Center of European Studies. The review’s title said it all: “Back to Europessimism: a Jeremiad Too Fond of Gloom and Doom.”

Much more to Hoffmann’s liking a few years later was a rather different book about Europe, this one written by Jeremy Rifkin and titled The European Dream: How Europe’s Vision of the Future Is Quietly Eclipsing the American Dream (2004). In those years, such titles were becoming a dime a dozen: Steven Hill’s Europe’s Promise: Why the European Way Is Best in an Insecure Age can stand in for others of the same ilk. ...