I moderated a panel at a recent conference on abortion at Princeton University that sought to bring voices from the prolife and prochoice sides together in the hope of finding common ground. Depending on whom you ask, the conference was either a fool’s errand or the beginning of a rapprochement in the abortion debate. More important, much of the conference was a reminder that, as Steven Smith argues in this splendid book, the quality of public debate on a range of important questions is “disappointingly shallow” because “the secular vocabulary within which public discourse is constrained to operate today is insufficient to convey our full set of normative convictions and commitments.”

Of course, there are many books about religion and politics. But for a topic that produces such regular paroxysms in our culture, there are few books addressing the question, How do we talk about how we talk about religion and politics? Part of the problem is that most books in this area are really about either religion or politics but not both. So there are good books about, say, the sociology of American religion that treat politics as the mapping of religious preferences onto the electorate. There are books in theology that advance arguments from within a religious tradition but are politically unsophisticated. And there are books in political philosophy that display a crude understanding of religion.

The Disenchantment of Secular Discourse is an exception because it presents a persuasive argument for the view that there is much lacking in how we talk about politics in the first place, and this is partly on account of the banishment of most normative (including religious) terms from public debate. “The very point of ‘public reason,’” Smith writes, in a broadside against John Rawls, “is to keep public discourse shallow—to keep it from drowning in the perilous depths of questions about ‘the nature of the universe,’ or ‘the end and the object of life,’ or other tenets of our comprehensive doctrines.” This is a familiar thesis to those who have followed the specialized literature of academic political philosophy of the last twenty years, but Smith’s book presents accessible and persuasive arguments for it. The book sets forth careful, if selective, arguments about the shortcomings of central themes in our contemporary political discourse. Smith is at his best when describing the incoherence or incompleteness of what are supposed to be the leading candidates for agreed-upon bases for political debate: freedom, autonomy, equality, neutrality, reciprocity, Martha Nussbaum’s “capabilities approach,” or John Stuart Mill’s harm principle. As a law professor, Smith is able to bring all of these abstract concepts to bear on important legal issues and constitutional cases and then to show how they come up short.

For example, Smith’s chapter on physician-assisted suicide addresses the elusive distinction drawn in law and moral theory between killing and letting die. If patients (or their proxies) are—as has been widely accepted for many years—free to make the decision to withhold or withdraw life-sustaining treatment, is there any reasonable basis upon which to say that they may not also request a physician’s help in committing suicide? That was the issue before the U.S. Supreme Court over a decade ago (the Court, like the Catholic moral tradition, held that such a distinction was reasonable), but Smith finds the reasoning offered for the distinction implausible. Smith’s discussion about the application of the principle of double effect to such cases is too compressed; suffice it to say he does not think the current debate provides sufficient grounds for distinguishing between intended and merely foreseen consequences. He also does not think it persuasive to say that patients and physicians “cause” the patient’s death in cases of assisted suicide but not when treatment is withheld or withdrawn—at least not if we are unwilling to bring into the discussion a richer understanding of what counts as causation or “nature’s course.”

Similarly, in the chapter on the harm principle, Smith argues that there is less than meets the eye. The basic idea of the harm principle is familiar to everyone, even if you haven’t sat through sophomore philosophy: crudely put, coercive legislation that restricts liberty is justified only when the proscribed conduct imposes some harm on other persons. Smith’s argument is that the harm principle is question-begging because the ascription of “harm” requires setting some baseline of what does or does not constitute a harm—a baseline that the harm principle itself does not provide and upon which the principle is parasitic. The harm principle is of little help in deciding whether possession of pornography, for example, should be prohibited by law. One must first decide, by some other criterion, whether pornography constitutes a harm.

As in a previous book that focused more squarely on topics in the philosophy of law, Law’s Quandary (Harvard, 2004), Smith diagnoses the modern malaise in terms that both specialists and laypersons can grapple with. We are, he claims, engaged in “smuggling” deeper claims into our public debates on a range of topics. This book continues Smith’s impressive line of work at the intersection of constitutional law (most especially the First Amendment), jurisprudence, and philosophy. His work is also genuinely interdisciplinary, as Smith manages to take contemporary constitutional doctrine seriously while also noting the deeper philosophical presuppositions at work in legal cases.

I have two lingering reservations, however. One is that law comes to be seen here too frequently as refracted philosophy or theology—as if the law did not have its own internal coherence and self-understanding but were merely a second-best way of conducting debates in moral philosophy. In such areas as physician-assisted suicide or abortion, that may be so, but I worry that the law suffers if we come to view those topics as typical of the law as such, or if we imagine that judges, lawyers, and law professors have a free license to practice moral philosophy. Second, Smith suggests at various points throughout the book that the loss of a coherent, teleological understanding of nature has led to our predicament—a familiar complaint set forth in great detail in recent works by philosophers such as Alasdair MacIntyre and Charles Taylor. Smith is less clear, though, about whether he thinks such a project of recovery is feasible or what the solution to the problem might be other than a plea, in the book’s last chapter, for “openness.”

But this is not to detract from Smith’s accomplishment. He has ably framed a set of important questions and called into question naive talk of equality, autonomy, harm, and the other terms in which contemporary debates are so often conducted.