Reviewed by: Apperzeption und Erfahrung: Kants Transzendentale Deduktion im Spannungsfeld der frühen Rezeption und Kritik Rolf Ahlers Martin Bondeli . Apperzeption und Erfahrung: Kants Transzendentale Deduktion im Spannungsfeld der frühen Rezeption und Kritik. Schwabe Philosophica, 10. Basel: Schwabe Verlag, 2006. Pp. 361. Cloth, €52.50. This book deals with the epicenter of modern philosophy, Kant's transcendental thinking self. It lives and breathes not only in the unity of reason in Kant himself, but also spells out how the problems that emerge in that conception were dealt with in the intellectual world of early German idealism. Bondeli shows how Kant's unity of reason is variously conceived by Kant as the "I think," the "highest point" of the "unity of apperception," as well as the more traditional concept of "soul," which is freighted with heavy metaphysical baggage. According to Bondeli, Kant had the greatest difficulty providing adequate reasons for that unity of apperception. Those difficulties are laid bare in part A of the first part of the book, "Kant's Problem of an Adequate Founding of the Original-Synthetic Unity of Apperception." The problem Bondeli lays bare provided ample fodder for Kant's critics, first and foremost the very early pre-Kantian Carl Leonhard Reinhold, soon, however, to emerge as the "Kantian of the first hour" in his Kantian Letters, but then also for Maimon, Schulze, Beck, and Fichte. Bondeli deals with the criticisms of those important thinkers in part B, "Reactions to Kant's Problem." The author points to the excellent arguments Kant himself provided against his contemporary critics. Those arguments also address the old metaphysical assumptions about God, humanity's soul, and the (real) world. They gain ground not only in Kant's practical philosophy, but also in his theoretical assumptions about substance and with substance the whole empirical world. But despite the "grave problems" in his thought, Bondeli says that Kant is "all in all convincing" with his arguments (92). As for how old metaphysical assumptions reappear in Kant, just consider what he said of the "eternal life of the soul" (85–87) and of the empirical, temporal, and psychological self (75–84) being of necessary relevance to the transcendentally reflecting subject. Of course, the center of Kant's thought, the relation of reality and ideality, needs to be identified as both "old" and "new" metaphysics. [End Page 475] Bondeli's book deals with ambiguities and contradictions mainly in the Critique of Pure Reason in its two editions of 1781 and 1787, which are at the center of the aforementioned "grave problems" in Kant's thought. These are what drove the post-Kantian reception and critique of the transcendental deduction. One grave problem is Kant's conception of the "original apperception" (26), though an array of other issues are also in need of clarification, such as the "relationship of logical and real, intelligible and empirical status of the original apperception" (27). That theme is worked through Bondeli's entire volume, practically on every page. In ferreting it out, many ambiguities come to light, such as in Kant's conception of the "I think": in opposition to Descartes's substantial definition of the "I think" as a res cogitans or thinking thing, Kant understands it as having (mere) intelligible status. On the other hand, Kant also understands the "I think" with Descartes as an "empirical proposition" (B 428) or as a substantive "I am" (B 138), and Kant provides reasons for both propositions. This a vexing situation and Bondeli—and the whole post-Kantian discussion—finds it troublesome, first because Kant is critical of Descartes's cogito conceived as thinking substance. In no way, Kant insists in the "Paralogisms of Pure Reason," is the transcendentally-thinking self to be associated with the concept of substance. That it is devoid of empirical elements is of paramount importance for its critical transcendental capacity of providing the conditions of knowledge. Second, Kant stresses, in the second edition, that "the proposition 'I think', or 'I exist thinking', is an empirical proposition" (B 428). The need to clarify the relationship of the logical and the real, the intelligible and the empirical status of the original apperception in Kant's thought implied a...