Chapter 3 addresses the relationship between the various tasks carried out in the Critique of Pure Reason by analyzing Kant’s multifaceted use of the term ‘transcendental.’ Challenging the received view, it maintains that Kant’s seemingly divergent accounts of the subject hinge on his conception of transcendental philosophy proper and transcendental critique as first-order and second-order branches of transcendental cognition, respectively. Drawing on a brief account of the seventeenth- and eighteenth-century history of the term ‘transcendental,’ the chapter seeks to show that Wolffian ontology and transcendental philosophy proper have more in common than is widely assumed: both disciplines can be said to provide a comprehensive account of the cognitive elements presupposed in any cognition of objects. On this account, the novelty of the Critique consists primarily in the second-order investigation into metaphysics that Kant calls transcendental critique. The chapter concludes by examining Kant’s criticism of the way his predecessors and contemporaries understood the terms ‘ontology’ and ‘transcendental philosophy.’

Chapter 1 elaborates on the historical context within which Kant developed his critique of early post-Leibnizian philosophy. It presents the pertinent elements of Wolff’s highly influential metaphysics and theory of cognition as well as the main thrust of Crusius’s critique of Wolff. Since Kant targeted both Wolff, Crusius, and those who followed in their wake, the chapter also discusses the main tenets of Crusius’s own metaphysics and the controversies that resulted from efforts among early post-Wolffian philosophers to reconcile Leibnizian monadology and Newtonian physics.

Chapter 4 seeks to resolve the apparent contradictions in Kant's account of the thing in itself and related terms by interpreting the relevant passages in light of his critique of Wolffian metaphysics. The chapter departs from both the two-aspect view defended by Allison and the two-object view that Guyer attributes to Kant. Moving beyond this opposition, the chapter dissociates Kant’s remarks on the objects that affect our senses from his use of the term ‘thing in itself’ and its cognates in the context of his critique of Wolffian and post-Wolffian metaphysics. In the latter context, it is argued, the term refers to things that can be thought but cannot constitute objects of cognition. The chapter shows that Kant’s account of the thing in itself in this sense and, hence, the distinction between phenomena and noumena allows him at once to limit the scope of former ontology to possible objects of experience and to affirm the ideas of the soul, the world as such, and God as noumena that can be thought but not known.

Chapter 8 is devoted to the positive goal of Kant’s reform of the theoretical part of metaphysics, namely, the system of pure reason he intended to elaborate on the basis of the propaedeutic investigation carried out in the Critique of Pure Reason. Drawing on the Architectonic, the Transcendental Dialectic, the Metaphysical Foundations of Natural Science, Kant’s lectures on metaphysics, and other texts, the chapter maintains that the Critique paves the way not only for a reformed version of general metaphysics or ontology but also for a reformed version of special metaphysics, namely, rational physics, rational psychology, rational cosmology, and rational theology. The chapter argues that the Critique does not preclude the possibility of a comprehensive account of the purely intellectual determinations of the ideas of reason themselves and, hence, is much less detrimental to former special metaphysics than is generally assumed. Thus, it seeks to bring out the common ground of Kant’s projected system and the metaphysical systems put forward by Wolff and Baumgarten. The chapter concludes by arguing that Kant’s later accounts of his intentions accord with his original plan.

Chapter 7 analyzes the Appendix to the Transcendental Analytic entitled “On the Amphiboly of the Concepts of Reflection.” Using Leibniz’s monadology as a prism, Kant here seeks to account for the ultimate premises of his critique and intended reform of metaphysics. More specifically, the chapter conceives of this critique as a variety of transcendental reflection that is guided by four pairs of concepts, including sameness and difference. In order to contextualize this account, the chapter briefly discusses Wolff’s and Baumgarten’s treatment of these concepts. Commentators generally assume that the activity called transcendental reflection is carried out in the Critique of Pure Reason alone. The chapter argues, by contrast, that Kant distinguishes the version of transcendental reflection that informs the ontology of his predecessors from the critical version enacted in the Critique. On this basis, it outlines Kant’s understanding of the difference between a Leibnizian employment of the concepts of reflection and his own.

Kant’s critical philosophy is reputed to impose strict limits on the cognitive activities carried out by the human mind. The mind is said to be able to generate empirical knowledge by means of two forms of intuition and twelve categories, and to delude itself whenever it illicitly ventures beyond these limits in search of a priori knowledge of the soul, the world as such, and God. Even if Kant may have been unable to demonstrate all of the claims he advances in the Critique of Pure Reason, we can be satisfied with the epistemological modesty his work proclaims: it allows us to pit Kant’s work against the extravagancies of philosophers such as Fichte and Hegel as well as to follow his beacon in our own even more modest pursuits.

Focusing on its 1781 version, Chapter 5 interprets the transcendental deduction in light of Kant’s overall investigation into the conditions under which metaphysics is possible. Whereas most commentators take the text to be mainly concerned with the conditions of possibility of empirical cognition, it seeks to demonstrate that the various strands of Kant’s investigation primarily aim to identify the conditions under which categories can be used to produce objects of a priori cognition as such. On Kant’s account, categories can contribute to the production of such objects only if they function as a priori rules for the thoroughgoing unification of successive representations, which is not the case if they are used to determine alleged objects such as the soul, the world as such, and God. Thus, I contend that the transcendental deduction passes a balanced judgment on Wolff’s unqualified affirmation of the possibility of a priori cognition of objects and Hume’s unqualified rejection of the same.

The second chapter seeks to clarify how Kant in the late 1760s and early 1770s came to conceive of the aim and main arguments of what was to become the Critique of Pure Reason. It focuses in particular on Kant’s evolving understanding of the act of critique. The heart of the chapter consists in an analysis of the Inaugural Dissertation. Challenging the prevailing view, the chapter highlights the critical impetus of the treatise by arguing that the specific criterion it employs to curb the ambitions of metaphysics – intellectual purity – is directed against an assumption common to Wolff, Crusius, and early post-Leibnizian philosophy in general. Moreover, it puts into perspective the alleged break between the Dissertation and the Critique by arguing that this early instance of critique is preserved in the Critique of Pure Reason. The chapter argues that Kant in this work introduces a new form of critique by arguing that any a priori cognition of objects necessarily rests on pure intuition.

Chapter 6 seeks to establish that Kant’s account of the schematism of the pure understanding in the Critique of Pure Reason yields the same result as the transcendental deduction, but does so by approaching the question concerning the legitimate use of categories from the angle of time qua pure form of intuition. On my reading, Kant conceives of transcendental schemata and categories as different instances of the a priori rules that determine how the mind can unify a manifold at all. Since transcendental schemata present these rules as ways of unifying successive representations, they can be said to constitute the sensible condition of any a priori cognition of objects. I take Kant to argue that Wolffian metaphysics ought to use categories independently of this condition in order to establish itself as a purely intellectual discipline and, hence, that a priori judgments about the soul or God do not amount to cognitions of objects.

Four years after the publication of the Critique of Pure Reason, Moses Mendelssohn noted in his Morning Hours: Lectures on God’s Existence that his weak nerves had prevented him from reading the recent works in metaphysics by Lambert, Tetens, Plattner, “and even the all-crushing Kant,” works that he admitted to knowing through “inadequate reports of friends and reviews” only.