The Review of Metaphysics

—In this book, Christopher J. Insole seeks to offer “a comprehensive study of the development of Kant’s conception of the highest good, from his earliest work, to his dying days.” Significantly, Insole resists the increasingly common tendency in Kant scholarship to articulate and defend secular or naturalized interpretations of Kant’s account of the highest good. Going far beyond the observation that Kant’s account of the highest good in the Critique of Practical Reason gives rise to a rational theology grounded on pure practical reason’s postulation of the existence of God and the immortality of the soul, Insole argues that Kant is attentive to the intimate connection between the concept of the highest good and the question of the nature and significance of the divine throughout his career. Accordingly, Insole’s account of the development of Kant’s understanding of the highest good aims to highlight and explain the fundamentally “theological motivations and significance of this concept.”

Insole’s book is a sustained effort to defend two core theses: (1) that “Kant believed in God, but that Kant is not a Christian,” and (2) that Kant’s reflections on the nature and significance of the highest good culminate [End Page 389] in a “profound and sincere philosophical religiosity.” Insole defends these theses by offering what he characterizes as the first “systematic treatment of [Kant’s] philosophical religiosity, understood in its own terms, and as expressed across his whole oeuvre, and not just in a limited range of texts such as Religion within the Boundaries of Mere Reason.” Ultimately, Insole concludes that Kant’s religiosity consists in both a “philosophical-religious hope” in the reality of freedom and an understanding of moral willing as constitutive of piety or holiness.

In order to clarify the structure of Insole’s argument, it is useful to divide his eighteen-chapter book into six parts. First, in chapters 1 and 2, Insole argues that in the 1750s Kant conceived of the human being’s highest good as the contemplation of God’s perfection as this perfection is embodied and expressed in the perfect order of the cosmos. Second, in chapters 3 through 5, Insole argues that Kant’s recognition that transcendental freedom is a necessary condition of human morality is the key to understanding the development of Kant’s ethical theory. Third, in chapters 6 through 10, Insole traces out the implications of Kant’s new conception of human freedom for his understanding of the nature and theological significance of the highest good. In these chapters, Insole begins to develop his account of Kant’s philosophical religiosity by explicating Kant’s conception of “the proper self” qua a transcendentally free, moral agent. Insole argues not only that human freedom replaces God and nature as religion’s proper object for Kant, but also that Kant thinks that moral willing can and should replace contemplation of the divine as the activity befitting human religious life. Fourth, in chapters 11 through 13, Insole argues transcendental freedom is both necessary and sufficient for the realization of the highest good and that “belief in freedom . . . is the lynchpin of [Kant’s] philosophical-religious hope.” Fifth, in chapters 14 through 16, Insole considers what role God can possibly play human moral life in light of Kant’s account of the necessity and sufficiency of human freedom for the realization of the highest good. Insole argues that Kant’s moral and philosophical system leaves no room for traditional conceptions of divine grace, but he allows that Kant permits belief in a form of grace according to which humans receive assistance from God consequent to their moral efforts. Sixth and finally, Insole completes his account of Kant’s philosophical religiosity by suggesting that Kant conceives of the “kingdom of ends” qua the realization of the highest good in the world as having divine qualities (chapter 17), before concluding that Kant understands the relationship between the moral law...