- For the Love of Metaphysics: Nihilism and the Conflict of Reason from Kant to Rosenzweig by Karin Nisenbaum
Nisenbaum offers an account of philosophical evolution in the wake of Kant’s critical revolution. She intends “to show that the development of post-Kantian German Idealism is propelled by the different interpretations, appropriations, and radicalizations of the Kantian view that the representation of the unconditioned (or absolute) by finite beings is a topic of practical, not theoretical, philosophy” (11). While this claim is not new, the different constellations within which it is established are new and original, as is the guiding thread of the book’s argument.
There are three such constellations. The first inventively combines Jacobi with Maimon. The second conventionally features early Schelling and Fichte. The last imaginatively associates middle Schelling with Rosenzweig, thereby allowing the argument to reach into the twentieth century. The thread that ties these constellations together is the following. Kant’s philosophy centers on the inner conflicts into which reason inevitably runs when it addresses metaphysical questions that it cannot answer. Since the last clause is to be read as meaning “that it cannot answer theoretically,” practical answers remain possible. This is the idea of the primacy of practical reason in metaphysical matters, which unfolds through the three constellations mentioned above. Jacobi demonstrates that theoretical reason, inasmuch as it is deprived of practical common sense, terminates in a rational monism that annihilates all reality; Maimon shows that a philosophical system has to be actualized by a person; and they both show that the specter of nihilism can be exorcised only by a practically actualized metaphysics. Next, early Schelling, in Fichte’s footsteps, grounds reason as a whole in the practical. Nisenbaum connects her historical exploration to a systematic discussion of transcendental arguments that deserves to be highlighted. According to her, these arguments (1) implement a coherentist strategy that consists in making explicit the presuppositional relations between our beliefs, (2) show that these relations hold in virtue of the self’s relationship with itself, and (3) invite others to adopt a philosophical standpoint that they are free to accept or reject. Finally, reading Schelling and Rosenzweig together shows that solving the conflict of reason amounts to the religious attitude of affirming the value of the world and of human action in it. This last constellation reveals that the finitude of our cognition is grounded in the incompleteness of being, so much so that all theoretical claims about God are in fact refusals of this metaphysical incompleteness, whereas our practical commitments and values are means of God’s revelation, because they accept His theoretical unknowability. [End Page 155]
This is an excellent book, and it is essential for further research on the development of post-Kantian thought. I must note, however, that I disagree with some of its main tenets. Most importantly, I believe that the primacy of practical reason needs a different interpretation. In Kant, the primacy of practical reason is a rational connective that unifies the interest of theoretical reason, namely, knowledge, with the interest of practical reason, namely, ethical action, by deciding which commitments of theoretical reason are necessary in the service of the practical interest. This does not mean that metaphysics falls into the domain of practical reason. Rather, the central question of whether the cognizable world is structured for a moral agent remains beyond the scope of that connective. In order to answer that question, Kant draws on an Augustinian-Lutheran distinction that Leibniz had already employed, stating that theoretical and practical reason refer to the regnum naturae and the regnum gratiae, respectively. In Protestant orthodoxy, these realms are irreconcilable: postlapsarian nature and grace will not come together until the regnum gloriae at the end of times. If we take into account this background of the distinction used by Kant, the metaphysical question of a world structured for a moral agent is a question neither for theoretical reason nor for practical reason. It will instead receive its answer in...