Johnathan O'Neill's Conservative Thought and American Constitutionalism since the New Deal is an important and much-needed addition to the burgeoning literature on conservatism in America. O'Neill's premise is that “the transformation of constitutional institutions wrought by the New Deal in the 1930s and elaborated by the Great Society in the 1960s” triggered “different kinds of conservatives [to] deploy . . . their respective core principles to criticize the new order and to defend [what] they most valued” (1). The volume's unique contribution is its focus on “how conservative thinkers understood the institutional arrangements of the New Deal order” (1–2), specifically the issues constituting the four major parts of the book: the administrative state, federalism, the presidency, and judicial review.

O'Neill divides conservative intellectuals into traditionalists, libertarians, Straussians (the East and West Coast versions), and neoconservatives, following the taxonomic classifications pioneered by George Nash in his classic The Conservative Intellectual Movement in America since 1945 (Basic Books, 1976). For those writers who did not explicitly affiliate themselves with one of these schools of thought, O'Neill assigns them by reference to “their intellectual lineage and associations, and their basic approach” (14). The two more easily defined groups are the traditionalists, who sought “a limited federal government that intruded only minimally into state and local affairs, so that families, churches, and communities could foster the good life according to inherited conceptions of morality, virtue, and justice” (6), and the libertarians (sometimes called classical liberals), who wanted “to maximize individual liberty” (7).

The Straussians, disciples of Leo Strauss's “designedly veiled and ambiguous teaching,” are harder to pin down beyond a core commitment to the idea of natural right “but in a way that takes into account the shortcomings of the modern doctrine of natural rights” (10, quoting James W. Ceasar, Designing a Polity: America's Constitution in Theory and Practice [Rowman & Littlefield, 2011]). Harry Jaffa and the West Coast Straussians have generally “defended the philosophy of natural rights and social contract,” while Allan Bloom and the East Coast Straussians “were more intransigently Platonic in doubting that any appeal to nature in politics ultimately could be justified by reason” (11). Finally, the neoconservatives, such as Irving Kristol and Norman Podhoretz, are even harder to define, with O'Neill describing neoconservatism as more of an “intellectual-political ‘tendency’ or ‘persuasion’” because neoconservatives often “began as liberals [who] incorporated the principles of other conservatives without following . . . any single doctrine” (12–13).

O'Neill's goal is to identify the central ideas and key thinkers driving the intellectual debates on the four major constitutional issues within each of the four schools of conservative thought without delving into the personalities or the “principled disagreements, feuds, and purges” that are already covered in the literature (14). Conservative Thought and American Constitutionalism is thus a book about ideas espoused by people deeply committed to the oft-quoted notion that “ideas have consequences.”

It is impossible to capture in a brief review the numerous themes and critical nuances O'Neill explores in his four-by-four matrix of issues and ideas. Moreover, since the book covers many decades in a political environment that continues to evolve, the volume is much more about the intellectual journey than the constitutional destination at any particular time. Ultimately, as O'Neill points out, “the New Deal altered the basic template of the nation's politics and institutions in ways that conservatives simply could not undo,” and, therefore, the book is also a story of how they “reluctantly” and “inconsistently” sought to find a way to adapt to the new reality (15).

Most of the book details other intellectuals’ ideas, but, in the final chapter, O'Neill concludes with his own. Despite all of the conservatives’ deep thinking about constitutionalism, they have, in O'Neill's view, largely ignored a critical yet “broken” element of American constitutional governance: Congress (285). His conclusion is a manifesto calling on conservatives to “see that [citizens’] ability to be a self-governing people is tied to the fate of Congress” (298). We therefore need to “relearn and rededicate ourselves” to constitutional “first principles” (298). That means revitalizing “authentic civic education,” “asking and expecting better of Congress and ourselves and accepting that government cannot be expected to solve all social problems” (298).

In a book so rich with the ideas of the more than one hundred men whose works are featured in the text, it is difficult to complain that there should have been even more, but there was little or no opportunity to hear from other politically important conservative constituencies, including evangelicals, such as the Reverend Francis Schaeffer, and, perhaps most notably, women. The story of the Equal Rights Amendment, for example, would seem to be a case study in how Phyllis Schlafly's conservative ideas had constitutional consequences. But neither Schlafly, nor the other women often discussed in works on modern American conservatism—Ayn Rand, Rose Wilder Lane, Gertrude Himmelfarb, Midge Decter, Amy Coney Barrett, and others—appear among the intellectuals under discussion.

Since O'Neill's research and analysis are impressively comprehensive, it may well be that the evangelicals and women who make up sizable percentages of conservative voters have not chosen to engage with the specific issues of constitutional structure and power on which the book is focused. If that is the case, perhaps finding a way to expand the conversations about the Constitution discussed in the book will become an important part of the civic education and “sustained attention” to Congress by conservative “intellectuals [and] activists” called for in the conclusion (298).

All in all, the volume's greatest strength is O'Neill's impressive ability to absorb a vast and often difficult corpus of works on conservative constitutionalism and provide readers with a sure-handed guide to the key principles and major arguments. The ideas are treated with care and presented with clarity. Moreover, the summaries of the many works under discussion are detailed enough for readers to follow and comprehend a series of complicated constitutional debates that have taken place over most of a century. As a result, this book is essential reading for political theorists irrespective of whether they share any of the viewpoints under discussion.