In the decades following World War II, an impressive collection of American Catholic intellectuals joined together to ponder what they believed was an urgent question: “What is an intellectual apostle?” These prominent scientists, linguists, historians, philosophers, and literary scholars—some of them clerics, but most laypeople—taught at Georgetown, Fordham, Notre Dame, and Catholic University, as well as Harvard, Princeton, Chicago, and Stanford. Eager to fashion a role for public intellectuals with a Catholic pedigree and a developed sense of vocation, they set about organizing an apostolate of the mind that could convincingly appeal to Catholic principles before a pluralistic audience, and in the process help form Catholic identity in the United States.

In A Catholic Brain Trust, Patrick J. Hayes chronicles the history and assesses the achievement of the organization these scholars created, the Catholic Commission on Intellectual and Cultural Affairs (CCICA). Hayes’s thorough and well-documented account reveals a postwar moment ripe for just such an undertaking. It was a period of religious enthusiasm throughout the country and Catholics’ place in national life had improved notably since the dark days of Al Smith’s presidential bid. Opposition remained, to be sure, especially from the likes of Paul Blanshard, the muckraking journalist and author who was an outspoken critic of Catholicism. But the members of this new brain trust hardly wilted before such critics. As polymaths and intellectual leaders, justifiably assured of their own wisdom and wit, CCICA members abandoned the defensive crouch long associated with Catholic engagement in the public square. These people knew their stuff, and relished a sustained theological discussion.

Which is not to say that Commission members shared a single mind. Indeed, as Hayes shows, their private meetings could spark intellectual fireworks. The group’s debate on Catholic conceptions of religious liberty, for instance, saw John Courtney Murray defending American notions of religious pluralism against such notables as philosopher Louis J. A. Mercier and priest-sociologist Paul Hanly Furfey. On this testing ground, Murray substantially worked out his own conclusions—and earned himself an order from his Jesuit superiors to cease publishing on the topic. In the longer run, however, Murray’s attempt to join the notion of a divinely bestowed human dignity to the idea of freedom of conscience won him a key role in the drafting of Vatican II’s Declaration on Religious Freedom, a document foundational to the church’s contemporary affirmation of universal human rights.

Confident as they were, CCICA members also undertook critical assessments of Catholic intellectual life. Surveying the scene in a 1955 lecture, John Tracy Ellis, the priest and prominent historian, chided his coreligionists for embracing the “generally nonintellectual, if not anti-intellectual, atmosphere in the United States.” Sociologist Thomas O’Dea soon chimed in, lamenting both the catechetical recitations that often marked the outermost bounds of Catholic religious knowledge and the intellectual defensiveness epitomized in the Vatican’s then extensive list of “forbidden books.” It was a point of irritation within the CCICA that apologetics trumped critical theological inquiry in Catholic higher education, and that laity well versed in the Catholic intellectual heritage often had to rely on diligent self-instruction—or even secular institutions—to make up for the dearth of robust church-sponsored training.

Such critiques had impact both here and abroad. In response, Jacques Maritain, the French convert, advocated a “sufficiently deep knowledge of theology to make Catholic intellectuals get into friendly contact with non-Catholic people without being afraid of them.” Christopher Dawson, another convert and a towering presence in Britain, counseled American Catholics against despair and stressed the necessity of tackling the “problem of translation,” by which he meant identifying the correct “language and idioms” for making Catholic principles comprehensible to “the modern pagan world.”

Searching for such an idiom—and doing so in the years immediately following the Holocaust and Hiroshima—the CCICA ultimately embraced human rights. It was motivated in part by the Commission’s desire to influence developments at the new United Nations—a deft move as the UN attained global reach. Yet one wonders at the seeming absence of attention paid to the percolating African-American civil-rights movement in the 1950s, or to the abortion debate in the ’60s. In part, Hayes suggests, energy flagged as members planned the 15-million-word New Catholic Encyclopedia—a project so imposing that the CCICA relinquished involvement before its completion. At times, these intellectual apostles missed the forest for the trees, burying their noses in research while neglecting monumental national conversations.

The CCICA’s heyday coincided, it turns out, with a postwar burst of institutional and intellectual vitality. In the decades before the organization finally disbanded, in 2007, its members included Supreme Court justices William Brennan and Antonin Scalia, writers Francine du Plessix Gray and Annie Dillard, and cardinals Avery Dulles and Francis George. But already by Vatican II, as enthusiasm spiked in other Catholic settings, the organization’s commitment to the “problem of translation” had waned, along with its zeal for public impact. Unimaginative leadership took its toll, as did the growing disinclination of intellectuals to be branded “generalists” and “humanists” in an age of research specialization.

So what of today’s aspiring intellectual apostles? Without doubt, they face considerable challenges in marshaling contemporary idioms to advance Catholic perspectives. Polarization and atomization long ago replaced the postwar “joining culture,” and despite such important initiatives as the University of Notre Dame’s Erasmus Institute, the University of Southern California’s Institute for Advanced Catholic Studies, and Collegium, an intellectual-spiritual formation program at the College of the Holy Cross, mentors in the professoriate often caution protégés to stick to their narrow academic fields. A media allergic to nuance is no help, and the difficulty of getting one’s ideas to appear in large, boldfaced type within the “keyword clouds” of our online horizons can be daunting. As in the past, Catholic intellectuals must also contend with the position, formidable in some quarters, that a dog-eared Catechism will yield the answer to any question of genuine import.

However the intellectual apostolate overcomes these hurdles, its future successes will surely be prompted by the imperative to love. Concluding his informative book, Hayes makes just this point; “toiling for the public good,” he reminds us, “is a measure of one’s love for God.”