The full complexity of the liberal tradition has always escaped the sound and fury of its most strident critics. In the most recent intervention in the debate over the tradition’s meaning, Cass Sunstein, the Harvard law professor and regulatory czar of the Obama administration known for his work in behavioral economics, recently published a New York Times essay, titled “Why I Am a Liberal,” that outlines “34 sets of claims about liberalism” in an attempt to defend the creed from attacks by the right and the left.

Yet the essay only feeds criticisms of liberalism by exposing its gravest vulnerabilities, including its ignorance of the anthropological nature of man; its failure to affirm the vital importance of the family and other sentiments of attachment that escape rationalist certitudes; its hesitation to distinguish between these sentiments and tribalism; and its utopian undertones. It is Sunstein’s thirty-fourth tenet of liberalism, however, that captures the tradition’s most perilous feature and threatens many of the prior liberal tenets he lists: the lack of a clear limiting principle.

In not one of Sunstein’s thirty-four tenets of liberalism does he mention, much less accurately describe, the moral and anthropological status of human beings: 1) Men and women are religious and spiritual creatures (not just that liberals hold strong religious convictions, as Sunstein acknowledges); 2) Men and women are born into preexisting social, religious, and economic institutions and customs; 3) Many of these institutions and customs are naturally hierarchical and unequal but are nevertheless interconnected, spanning the sacred and temporal worlds; and 4) Men and women bear moral obligations to their fellow man that are not the product of subjective consent and preference. These insights are the closest thing to fixed—and apolitical—truths as any concerning the human condition. It is thus difficult to provide a persuasive defense of any political or intellectual tradition without validating them. Sunstein never does.

Similarly, nowhere in his 34 claims about liberalism does Sunstein mention the family. Sunstein rightly condemns tribalism for eroding the possibility for productive dialogue based on mutual respect. But he fails to demonstrate awareness of the differences between tribalism and what Edmund Burke called “just prejudice,” the inherited wisdom of social institutions, customs, and affections emerging from a blend of reason and habit. Our family is the noble embodiment of just prejudice: We hold sentiments of attachment to our kinship networks, even if we cannot fully rationalize them.

Would Sunstein describe attachment to one’s family as tribalism? To one’s local community? To one’s own nation’s distinctive rituals and institutions? A person can find meaning and purpose in his allegiances to social groups without submitting to the base instincts of reactionary tribalism, whose desperate radicalism itself militates against the conservative disposition. Negligence of this distinction reveals one of the nagging weaknesses of liberalism: its struggle to comprehend man’s precognitive and organic affections that escape rigid measurement.

Sunstein does acknowledge that liberals, far from being antagonistic toward traditions, have in fact embraced them. But consider those traditions Sunstein identifies (which, as he suggests by implication, predate the birth of modern liberalism): republicanism, checks and balances, free speech, freedom from unreasonable search and seizure, freedom of religion, private property, due process rights, and equal protection of the law. These traditions are of course crucial to sustaining a liberal political community. But he does not underscore the family, religious institutions (he offers one fleeting reference elsewhere), and an inherited code of ethics as examples of tradition, even though these are arguably more indispensable than the eight listed above in perpetuating a free society. We may push further: Sunstein’s liberalism is not possible without prior religious, social, and ethical preconditions. For it is the family, not the individual, that is the fundamental social unit for a flourishing commonwealth; and it is the Ten Commandments and the Sermon on the Mount, not personal agency, that (among various Scriptural teachings) comprise the enduring source of morality in Western civilization.

Also glaringly absent from Sunstein’s tenets of liberalism is any explicit recognition of original sin or the deep imperfections of man. One can certainly read these notions into some of Sunstein’s liberal principles—his brief nod to personal self-restraint, for instance, conveys an awareness of man’s capacity for intemperance—and the very premise of his nudging project is that man’s rational faculties are limited. But if a thinker is going to catalog thirty-four sets of claims about liberalism, it is striking that not one of them highlights, yet again, an indisputable and elemental quality of man’s nature: its inherent frailties.

The most damning indictment of Sunstein’s conception of liberalism, however, rises from his final tenet, which reads:

Liberals look forward as well as backward. They like to think that the arc of history bends toward justice. William F. Buckley Jr. said that his preferred form of conservatism “stands athwart history, yelling, Stop.” Liberals ask history to explain its plans, and they are prepared to whisper, “Go.”

This framework reinforces all of the worst fears about liberalism: its vain belief in the inexorable march of progress that leads to puffed-up pride; its reflexive submission to the currents of history; the facile insinuation that novelty is always for the better; its devilish flirtation with utopianism; and its illiberal, unimaginative, rigid, and unfair dichotomy between those who believe in progress—liberals!—and those who resist progress—everyone else. All of these implications reflect the tradition’s most glaring and dangerous vulnerability: the absence of a firm limiting principle.

Limiting principles guard against faith in false gods, resist hubris, puncture the pretensions of presentism, cool the temptation for radical change, breed gratitude, combat discontentment, prize judgment, impose moral duties, and alert man to the varied textures of human affairs. Limiting principles also teach that one can retain a guarded hope in man’s capacity for progress—best understood as meaningful, substantive reform proportional to the defects of existing institutions and practices in pursuit of the common good—without assuming that progress is inevitable.

Yet some of the examples Sunstein furnishes in his essay about liberalism explode these imperatives, and in fact contradict many of the liberal principles he outlined earlier in his essay: Did the New Deal strengthen or scorn the rule of law and free speech? Did liberals whispering “go” to the Great Society promote individual dignity or encourage individual poverty? Have the Supreme Court’s successful attempts to remove religion from the public square (a few recent cases notwithstanding), in the name of freedom of religion, promoted freedom or aided in the weakening of Americans’ moral conscience? If the liberals to whom Sunstein is referring were indeed looking forward, they were not looking forward far enough.

Sunstein is therefore guilty of casting a net far too wide: If liberalism can be both for or against the New Deal; for or against the administrative state; for or against progressive taxation; for or against Lyndon B. Johnson’s Great Society; for or against treating human beings as means rather than ends or ends rather than means, what then is the limiting principle to liberalism? If the only thing thwarting the advance of liberalism is a couple of cranks yelling “stop,” then there really is no limiting principle.

Sunstein may respond: Of course there is a limiting principle. As he writes, constraints on freedom must be justified, such as prohibitions on using dangerous drugs. But that begs the question rather than answers it. What qualifies as a justification? Perhaps the answer is the harm principle, which saturates the logic of his essay: If an action infringes on someone’s free speech, that should be limited; or if an action infringes on someone’s personal agency, that should be limited.

But then how can he seriously call for a second Bill of Rights in the image and likeness of FDR’s New Deal—including a right to employment, food, and health care, whose enforcement would require an even windier maze of bureaucratic rules than the one we have now—when the first New Deal imposed serious restrictions on freedom, personal agency, and democracy? It is similarly difficult to reconcile Sunstein’s preference for nudging, dripping with its technocratic condescension (not to mention its long-term ineffectiveness), with human dignity.

In other words, what if the march of progress actually menaces liberal principles? Sunstein thus conveys two conflicting messages: On the one hand, the flow of history naturally advances liberal ideals. On the other hand, if historical developments threaten liberal ideals Sunstein rightly holds dear, such as free speech, the rule of law, and freedom, one suspects he would not be whispering “go” but screaming “stop.” Should society engage in some sort of utilitarian calculus to determine whether particular policy reforms promote greater freedom overall? Who makes this calculation—individuals, family, communities—or perhaps technocrats?

The point is not to condemn the entire edifice of the liberal project but to suggest prescriptions to offer a more persuasive defense of it. Yet Sunstein’s essay, while highlighting key principles of liberalism, confirms the deepest suspicions about the tradition, not to mention about his own brand of scientific utilitarianism. The best thinkers in the liberal tradition, including Smith, Madison, Hayek, Constant, and Tocqueville (some of whom Sunstein mentions), were all alert to the limits of liberalism, the superstitious dogma inherent in the belief in the relentless march of progress, and the myriad ways liberal polities rely on preliberal commitments. Indeed, many liberals, as Helena Rosenblatt has shown and as Sunstein himself concedes, have been serious advocates of morals and religion.

A more compelling way to defend liberalism, then, would be to anchor the tradition in the anthropological nature of man as a religious creature born into preexisting rituals and customs, with preexisting moral obligations that are not the product of individual preference; sentiments of attachment, including the family, that transcend narrow quantification; a distinction between such sentiments and reactionary tribalism; original sin; and a limiting principle. If earnest liberals such as Sunstein sufficiently weave such considerations into their definition of liberalism, they would provide a more robust apologia of the tradition. Some might even call it conservatism.