Autonomy—the notion that human beings write the laws that govern themselves—is one of the central concepts of modern thought. For Americans, the idea that democratic citizens are self-legislating is embedded in our founding documents, the Declaration of Independence and the Constitution. The idea continues to germinate, however, as more and more constituencies wish to contribute to the generation of the laws that apply to them. Consider, for instance, the recent motto of the international disability movement—“Nothing about us without us”—that gives voice to a new claim to autonomy. The notion has its roots in the Bible (Romans: “the gentiles were a law unto themselves”), was given a secular formulation in Rousseau's Social Contract, and continues to be reconceptualized and reapplied up to the present, as with John Rawls's defense of political, rather than moral, autonomy. Yet no thinker in the history of philosophy has thought about the problem of autonomy as deeply or influentially as Immanuel Kant (1724–1804). Thus, Susan Meld Shell's careful and systematic examination of Kant's reflections on autonomy should interest not only Kant scholars but also anyone thinking about the moral foundations of liberal democratic politics.

One of the great contributions of Kant and the Limits of Autonomy is to show that Kant's philosophy is entangled, from beginning to end, with theological and religious concerns. Shell begins her book with a discussion of his famous description, in the Groundlaying of the Metaphysics of Morals, of philosophy's “precarious position.” Philosophy, on the one hand, cannot reside solely in the empirical world because it would lack a higher vantage point from which to criticize the present. On the other hand, his Critique of Pure Reason was written precisely to keep speculative philosophy within the bounds of sense. Kant never endorsed the voluntarist position that God's will simply dictates our moral laws. Yet his challenge was to find a new philosophical foundation for the spirit of Christianity, one that did not claim theoretical access to a transcendent realm. Shell shows that Kant entertained at least three theses about theology, religion, and moral autonomy:

God is necessary to morality. In the 1781 edition of the Critique of Pure Reason, Kant argues that human reason possesses pure moral laws, but that humans need to believe in the existence of God and a “world not now visible” for these “objects of emulation and awe” to become “incentives for resolve and execution.” Despite Kant's epochal substitution in the first Critique of (human-centered) epistemology for (God-centered) ontology, he still assumes that God is needed to enforce moral laws.

Human beings are morally autonomous. The Groundlaying (1785), Shell observes, is the seminal work of modern ethics (p. 122) because of its still-revolutionary claim that human reason, without any supernatural assistance, can find and establish the supreme principle of morality. Philosophy, Kant assures his readers, can be firm even though there is “nothing in heaven or earth” upon which it depends. Merely by reflecting upon common sense (in Section I), or ethical rational knowledge (in Section II), he eliminates corrupt or misleading conceptions of morality to arrive at its true principle. In its final formulation, the principle states that man is “subject to his own and yet universal legislation.” Here, Shell says that Kant boldly argues that human beings can make and observe moral laws without divine revelation or support: “One could say that Kant put individual ‘autonomy’ on the map” (p. 2). One could also say, more polemically, that Kant granted philosophic legitimacy and prestige to atheism.

Human beings need (Christian) religion. Late Kant (1789–98) was obsessed with the question of the aspects of Christianity that were necessary for, compatible with, or opposed to moral autonomy. In a chapter on “Kant's Jewish Problem,” Shell shows that Kant's fondness for his Jewish students (such as Marcus Herz) and respect for Judaism's prohibition on graven images (in the Critique of Judgment) turned, near the end of his life and under pressure from the Prussian religious-political establishment, to contempt for Jewish ceremonialism. In the Conflict of the Faculties, Kant argues that Catholicism and Protestantism, despite minor historical differences, nurture a pure moral faith that insists, for instance, that Jesus (and not Moses) personifies the moral ideal. Kant's call for pure rational religion becomes, in effect, a call for a Christianity purified of Judaism. His religious writings “suggest a thought that Fichte and other members of the Christlich-Deutschen Tischgesellschaft will run with: de-judaization as the negative image of the republican idea” (p. 328). Shell notes that Kant helped launch Fichte's career; she discretely passes over the fact that Hitler was a devoted reader of Fichte.

What lessons does Shell draw from Kant's thoughts on autonomy? The first is that there is a limit to philosophy's explanatory power. Despite Kant's best efforts (as in Section III of the Groundlaying), he never could specify exactly what legislates in human reason, or where reason originates: “Kant, in short, admits that morality has a mysterious core” (p. 4). This is an amazing statement. Mystery derives from the Greek word mysterion (“secret rite or doctrine”), from the verb myein (“to close, shut”), as in: the initiates to a mystery are not permitted to speak about it. The Greeks used the same word—logos—for both reason and speech: as if the essence of rational position is to be articulable in words. Shell, in effect, concedes the postmodern point that Kant's language of purity conceals a subterranean, and perhaps sinister, motive—as when Kant claims that pure moral religion entails “the euthanasia of Judaism” (p. 325). (Compare to Max Horkheimer and Theodor Adorno's chapter on “Elements of Anti-Semitism: Limits of Enlightenment” in The Dialectic of Enlightenment, 1944.) The second lesson that Shell draws, however, is that liberals need to respect the limits of rational morality and, thus, defend certain Kantian premises—such as the bindingness of the moral law and the importance of desert—against “relativistic” or “historicist” critics such as John Rawls (pp. 5–8).

To review, the exoteric message of the book is that liberals need to fight for their core commitments (e.g., moral duty, desert), while the esoteric message is that these commitments rest upon shaky grounds. In her recent contribution to The Cambridge Companion to Leo Strauss (2009), Shell notes that the task of the social scientist “in the best sense” is to “guide liberal democracy as its friend while also alerting it … to the particular dangers of the present” (p. 190). Strauss and his students turned primarily to the ancients to provide the moral tonic that liberal democracy needs. In a classic counterinsurgency strategy, however, Shell co-opts Kant to remedy the “irresponsible half-heartedness” of contemporary liberal democratic politics. Her book merits a book-length response. For now, I note that Shell minimizes Kant's call (as in his essay “What is Enlightenment?”) for all adults to exercise intellectual, moral, and political autonomy, even if that ultimately means overstepping Kantian limits on thinking, acting, or feeling. More importantly, Shell's defense of autonomy in its original (Kantian) intent encumbers many groups—unforeseen or unappreciated by Kant in eighteenth-century Prussia—who want a hand in the governance of their own lives.