In her insightful book For the Love of Metaphysics, Karin Nisenbaum explores the role of practical reason within post-Kantian German Idealist attempts to rescue metaphysics from the threat of nihilism.1 Nisenbaum's book encompasses a broad scope, yet for this review, I will focus on her interpretation of Immanuel Kant's "fact of reason," which establishes the practicality of pure reason and is thus foundational for Kant's practical metaphysics. This limited focus is justified by the central role that the fact of reason plays in Nisenbaum's interpretation of the development of post-Kantian philosophy. According to Nisenbaum, the most philosophically interesting developments after Kant consisted in a radicalization of Kant's prioritizing of the practical over the theoretical employment of reason (LM 11-2). Her book begins with what she calls the "conflict of reason": namely, its search for knowledge of the unconditioned, which it cannot obtain through its theoretical employment. The post-Kantian philosophers Nisenbaum is interested in agree with Kant that it is only the practical employment of reason, and the faith and love of metaphysics that it generates, that can meet reason's demand. She thus shows little sympathy for those who, like G. W. F. Hegel, either aim to overcome the distinction between theoretical and practical reason, or to replace faith and love of metaphysical wisdom by absolute knowledge and possession of wisdom (LM 16). Nisenbaum is interested in post-Kantian philosophy not as a departure from Kant, but as a

defense of the Kantian idea that the representation of God or the Absolute by finite beings is a topic of practical, not theoretical, philosophy. [LM 16]

Nisenbaum bills her reading of the fact of reason as Fichtean, yet my aim here is not to engage with Fichte interpretation. Instead, I wish to look more closely at this reading as an interpretation of Kant, for seeing whether one can in fact think of the post-Kantians as radicalizing one of Kant's insights. Nisenbaum is primarily interested in what Kant calls the 'deduction of freedom' in the Critique of Practical Reason.2 This deduction belongs to Kant's overall aim in his second Critique of showing that pure reason is indeed practical (KpV 5:15), or equivalently, that human freedom is real (KpV 5:3). Unlike the Groundwork of the Metaphysics of Morals, which on many readings attempts to provide a deduction of the moral law, the second Critique begins with the moral law as being a fact of reason and from this principle it provides a deduction of freedom. In my reading, Nisenbaum's position in the scholarly debate about the relation between the Groundwork and the second Critique is not entirely clear. But she does suggest in several places that on a Fichtean interpretation the second Critique aims to "ground moral obligation" (LM 147), which could mean that it does not conflict with, but supports, a reading of the Groundwork as attempting to provide a deduction of the source of all moral obligation: namely, the moral law.

Nisenbaum argues that there are two steps in Kant's deduction of freedom through the fact of reason. The first step is to acknowledge that the moral law is the law of transcendental freedom (that is, it defines what it is to be free, and thus, what it is to be a person). She writes:

in step one, Kant derives the moral law from the concept of a transcendentally free agent. [LM 135]

It should be noted that if I can derive the moral law from the concept of transcendental freedom, I must be capable of knowing the moral law from knowing what it is to be free. Nisenbaum also acknowledges that the concept of morality implies the concept of freedom for Kant, leading to the reciprocity thesis that she formulates through a double conditional:

If I am a transcendentally free rational agent, then I am bound by the moral law; and if I am bound by the moral law, then I am a transcendentally free rational agent. [LM 134-5]

Nisenbaum seems to read the conditional on each side of the reciprocity thesis as a claim about conceptual dependence (being free entails being moral, being moral entails being free). Her second step consists in "actualizing the reciprocity thesis" or in showing that "the moral law applies to us" (LM 135), which in turn consists both in (a) showing that the content of the concept, the essence of freedom applies to a moral agent—this is the "synthetic or ampliative moment in the argument" (LM 136)—and (b) in performing this application, by taking up the first-person practical standpoint of a free moral agent. These two moments, Nisenbaum argues, correspond to the Fichtean distinction between the fact of reason seen as "content (eine Tatsache)" and "fact as performance (eine Tathandlung)" (LM 141).

This reading by Nisenbaum faces several interpretive and philosophical challenges. I will focus on three related issues in what follows.

Self-Consciousness of Practical Reason

First, Nisenbaum's interpretation suggests that one could know the essence or being of a practical reasoner (that is, one could know what it is to be transcendentally free or governed by the moral law), without yet knowing whether this essence applies to me: I could know what it would be to be subject to the moral law, and thereby know what being free would entail, without knowing that I myself am subject to the moral law, or that I am free. This is the distinction between Nisenbaum's two steps: first, the reciprocity thesis gives me the concepts of the moral law and of transcendental freedom. Second, I apply this thesis to myself. This position is hard to square with Kant's suggestion that the moral law is the "self-consciousness of a pure practical reason, this being identical with the positive concept of freedom" (KpV 5:29), since that would mean that there is no representation of the moral law independent of thinking that it applies to me. To be conscious of the moral law is to be self-conscious: there is no conception of the moral law that is not a self-conception; therefore, it would seem that, contrary to Nisenbaum's reading, to think in terms of a moral "must" is already to think that "I must."

This is not to deny that there is a step to be taken from being conscious of the moral law to being conscious of freedom, corresponding to the step from ought to can. But this would not be the same as the distinction between Nisenbaum's two steps. Instead, it seems to correspond to the two moments within her second step, namely, "actualizing the reciprocity thesis" (LM 135): first, I apply the content of the moral law to myself: this means that I think that "I must." Second, I perform this application through consciousness of my freedom when thinking that "I can." Nisenbaum interprets the deduction of freedom not as the immediate step from ought to can, but as the step from the reciprocity thesis (as a thesis about mere conceptual implication) to its application to me. But if it is impossible to think of the moral must without thinking that "I must," it seems more plausible to interpret the deduction as moving from ought to can.

Why does this matter? The most significant upshot of Nisenbaum's interpretation is that it leaves room for the possibility that I might not apply the moral law to myself, that is, that I might not take the first step of her second step. Thus, Nisenbaum writes that it is possible "to acknowledge or deny my humanity" (LM 142). It is only if I choose to take Nisenbaum's second step, that is, if I perform the deed of applying the moral law to myself, that I express the "commitment to the value of [my] humanity or rationality" (LM 141). Along Fichtean lines she argues that one is summoned or invited to apply the reciprocity thesis to oneself, but one may decline the invitation and thus fail to be transcendentally free. She interprets Kant's example of being faced with the choice of either giving false testimony against an honorable man, or facing death at the gallows, "as an invitation to have as an ideal pure self- determination" (LM 140). That is, one is invited to step into the first-person standpoint of practical reason, within which one must think of oneself as transcendentally free, and as striving to do what one knows one can do.

Against this it needs to be said that Kant does not present the example as one in which a human being is summoned to step into the moral standpoint. One is asked whether one could sacrifice one's own "love of life" within the context of already knowing that, in this situation, one ought to (KpV 5:30). One is not being asked to enter the standpoint of considering an "ought," but rather to embrace the awareness of "I can," that is, to recognize the practicality of one's cognition of what one ought to do.

Nisenbaum acknowledges that the possibility that I may choose not to be committed to the value of my humanity (LM 142) is,

no longer a standard Kantian view on the nature of freedom. In the introduction to the Metaphysics of Morals, Kant explicitly rejects the idea that freedom consists in the ability to determine oneself against one's lawgiving reason—the capacity for evil. [LM 140]

That is, according to the now standard reading of Kant, there is no choice to be made as to whether I should or should not value my humanity, for to be conscious of myself is to already be conscious of my unconditional value and of moral obligation. It is within the context of my personality, my valuation of humanity (the ought of my own existence), and my consciousness of transcendental freedom that I make concrete choices, and in such choices I may or may not contradict my essence as a free person. That is, I may or may not turn away from myself.

But if Nisenbaum acknowledges a departure from Kant in her interpretation of the deduction of freedom, which still allows for a freedom to accept or deny one's humanity, does this mean that she acknowledges that the post-Kantian interpretation of the deduction of freedom is a departure from Kant? If so, it would be helpful if she were to comment on how one can think of the post-Kantians as radicalizing Kant's insight into the primacy of practical reason. It is also possible that the post-Kantians think there is another capacity besides Kantian practical reason—namely, the capacity to choose whether or not one should commit oneself to the demands of practical reason.

Existence

A second challenge arises from Nisenbaum's understanding of one's existence—or equivalently, the actuality of freedom—as an instantiation of the essence of freedom. To exist, according to Nisenbaum, is to make the moral law actual, that is, to instantiate this concept in the world. This would seem to conflict with Kant's claim that the existence of persons is not the realization of an end or concept, but that their existence is in-itself an end. So, to exist, for persons, is not to realize or instantiate some concept or archetype. For each person, the end is one's own existence. As I recognize my existence as an end in-itself in cognition of the moral law, it seems that there is no cognition of the moral law that precedes cognition of my existence qua person.

Martin Heidegger puts this point by emphasizing that, for Kant, cognition of the moral law is always already cognition of one's existence, and thereby also of the actuality of freedom (or of the practicality of pure reason). On this reading, there is no ideal or essence of personhood that my existence actualizes, for my existence is not to be understood as actualization or instantiation. Heidegger writes:

individual human beings [are not] realizers of the law in the same way that individual tables realize the essence of tablehood. It is not a formula and rule that we come to understand, but the character of the specific actuality of action, i.e. what is and becomes actual in and as action.3

My essence consists in nothing other than my lawful existence. Although Heidegger may be guilty here of assimilating Kant into his own view, which is not that existence precedes essence, nor that essence precedes existence, but that my essence is my existence, Kant does appear to share with Heidegger the inseparability of existence and essence regarding persons. One is immediately aware of the fact of reason in any actual (existing) willing, for the moral law is the self-consciousness of willing (that is, of practical reason): "to actually will is to will nothing else but the ought of one's existence" (EHF 198).

This point has relevance for understanding how it is that humans acknowledge other persons, a topic of great interest to Kant's successors. For if acknowledging another requires first applying the concept of "person" to the other (instantiating the concept), this would not be an act already performed from within the practical standpoint of morality or personhood, but rather would have to be an act that precedes a practical relation to another human. So, it would have to be a theoretical judgment that I must first make about others in order to then be capable of making practical judgments about how to treat them. Thus, failing to acknowledge another person would not be a practical mistake. I could excuse myself for failing to treat this person with respect by saying that I simply did not realize that this other human being belongs to the practical standpoint. If, on the contrary, acknowledging other persons is a matter of practical knowledge of their existence, it would already involve respect for them as persons and thus as ends in themselves, which I contradict when I treat them as a mere means. In this case it would not be possible to avoid taking responsibility for evil treatment of others by pleading ignorance of their personhood: the evil can be found within me, namely in the contradiction within my will.

The Ungroundedness of the Ground

Finally, Nisenbaum's reading of the biconditional in the reciprocity thesis is difficult to make compatible with Kant's claim stated in the Critique of Practical Reason that only the moral law is the ratio cognoscendi of freedom, while freedom is the ratio essendi of the moral law. This means that the two conditionals are to be read in radically different ways: in one direction, one is told that one can know what it is to be transcendentally free from knowledge of the moral law. (And if my interpretation above is correct, there is no such knowledge without already knowing myself actually to be free.) But in the other direction, one is told only that the being or essence of the moral law rests on transcendental freedom—and not that one can know the moral law from knowledge of the concept of freedom. This suggests that freedom is a hidden, unknown ground of the moral law, and thus that there is some ungroundedness in the moral law when seen as a fact of reason. Kant says that the moral law is a synthetic a priori proposition that "immediately announces itself as lawgiving" (KpV 5:31). And if it does so without a rational ground, while itself grounding the possibility of morality, it can be understood as an ungrounded ground. So, the fact of reason is not grounded in any cognition or concept—in particular, it is not grounded in cognition of one's freedom. Freedom gives me the fact of reason, as it were as a (divine) gift, but it gives this gift without telling me why: freedom is merely a ratio essendi of the moral law, not its rational ground (ratio cognoscendi). In this respect Kant's fact of reason is radically unlike Johann Gottlieb Fichte's first principle, which as an intellectual intuition can be understood as a self-grounding ground (and thus as a ground that has no darkness in its core).

Nisenbaum acknowledges that Fichte departs from Kant in extending the grounding act of self-positing (Fichte's fact of reason) to "all constraint or necessitation, both in the theoretical and practical domains" (LM 147). But this is just another aspect of Fichte's departure from Kant's understanding of the fact of reason. One way to emphasize the synthetic character of Kant's moral law is to acknowledge its dependence on theoretical reason. For Kant, the person supersensibly exists only under the condition of the sensible existence of a rational (theoretically cognizing) animal (or as a human being). As a synthetic proposition, the fact of reason extends beyond both animality and humanity to constitute my personality, but it also presupposes my existence as animal and as human.4 Thus, for Kant, I do not posit my own existence as an animal in the sensible world through practical reason. On similar grounds practical cognition presupposes theoretical cognition for Kant: one cannot simply assimilate the metaphysics of nature into a metaphysics of freedom, for the former is a condition for the possibility of the latter. In this regard it is unclear that Fichte can be seen as acknowledging the primacy of practical reason in Kant's sense, that is, in the sense that requires a radical distinction between the practical and theoretical employments of reason.