On the face of it, they share little in common with the rarefied intellectuals of Political Pilgrims. Yet their estrangement from Western society and the force of their belief in an alternative system far superior to it, evidenced in interviews they have given and other forms of personal testimony, suggest that they share certain discontents and susceptibilities with the subjects of Hollander’s study.

Among the countless examples of folly cited by Hollander is Sidney and Beatrice Webb’s tome Soviet Communism: A New Civilization?, in which the Soviet penal system is praised for—wait for it—its progressive spirit. The second edition of this book, from which, as the historian Robert Conquest noted, “the question mark was triumphantly removed,” was published in 1937—“at precisely the time,” Conquest observed, that “the regime was in its worst phase of gloomy, all-embracing terror.”

How could the Webbs and others like them have gotten it so wrong? They were clearly foolish, but they were not stupid. Indeed, writes Hollander, many of the intellectuals in his survey were widely revered for their fierce intelligence and lively skepticism. Hollander contends instead that they wanted to be deceived about the failures and depredations of the societies they visited. And this, he theorizes, was in turn because, psychologically, they needed to believe in the existence of a perfect social system that not only exemplified their deepest ideals but also gave voice to their deepest misgivings about their own societies.

“Wishful thinking,” the sociologist Karl Mannheim wrote, “has always figured in human affairs. When the imagination finds no satisfaction in existing reality, it seeks refuge in wishfully constructed places and periods.” Hollander approvingly reproduces this quote in his introduction to Political Pilgrims, and one of the great merits of his book is the clarity and force with which it shows how desire can supersede and subvert critical thinking.

The recent migrations to ISIS, just like the political pilgrimages before them, are yet further testimony to the power of wishful thinking and how desire can trump reason.

Earlier this month, it was reported that a family of 12 from Luton, England—including, according to the BBC, “a baby and two grandparents”—had made the journey to Syria. It was the second family believed to have left the United Kingdom for the Islamic State since May. Was the family coerced or, as one relative has suggested, manipulated into going to Syria? Were they the victims of some collective psychosis? Not a chance, if a press release purportedly from the family is to be credited. The BBC acquired the statement from an individual claiming to be an Islamic State fighter, though the media organization could not verify its authenticity.

“None of us were forced against our will,” it said, describing a land “free from the corruption and oppression of man-made law ... in which a Muslim doesn’t feel oppression when practicing their religion. In which a parent doesn’t feel the worry of losing their child to the immorality of society. In which the sick and elderly do not wait in agony, tolerating the partiality of race or social class.” It also derisively alluded to the “so-called freedom and democracy” of Western states.