Part III is dedicated to the critique of pure reason, namely, the discipline contained in the Critique that is charged with accomplishing its task as the doctrine of method of metaphysics. I argue that the critique of pure reason has a positive and a negative task. Chapter 5 is dedicated to its negative task. The critique must show that metaphysics is capable of systematic coherence. I take a body of cognitions to be systematically coherent when: (a) the cognitions belonging to it are interconnected in a way that involves relations of either logical implication, explanatory support or both, and (b) it does not contain contradictions. Kant establishes that metaphysics is able of systematic coherence by setting limits to cognitions. I argue that Kant sets these limits by limiting the validity of the root concepts for the cognition of objects analysed by transcendental philosophy. I consider how and where these limits are established. I claim, first, that Kant does not follow a univocal strategy in establishing these limits and, second, that he presents arguments for establishing these limits in the Aesthetic, Analytic, and Dialectic. I focus on the arguments in the Aesthetic and the Dialectic in particular.

The conclusion summarizes what the main consequences of the book for out understanding of the critique of pure reason are. It also emphasizes that the understanding of the critique that it is proposed is not applicable to the second and third Critiques. In those works, Kant appears to have changed his mind concerning what the main taks of a critique of pure reason is.

This chapter has two aims. First, I want to provide an interpretation of Kant’s critique of dogmatism, with Christian Wolff as the chief defender of that approach. I distinguish between three different characterizations of dogmatism that Kant provides. I show that Kant regards Wolff as a dogmatist in two of these senses and explain how he can consistently hold that view. Second, I aim to offer an account of Kant’s views on the relationship between his ‘critical’ method and Wolff’s ‘dogmatic’ method, since Kant suggests that the latter is not without its merits.

In a passage in both editions of the Critique of Pure Reason, Kant describes what he wants to accomplish there as a ‘doctrine of method’ (A82–3/B108–9). In the B-Preface, he adds that the Critique ‘is a treatise on the method’ (Bxxii). In this chapter, I argue that the best way to understand these claims is to see them as an indication that the Critique is the doctrine of method of metaphysics. I start by clarifying what a doctrine of method is for Kant and distinguish between the doctrine of method of general logic and the doctrines of method of particular sciences. In a second step, I argue that the Transcendental Doctrine of Method is the particular doctrine of method of metaphysics. Furthermore, I explain how this is compatible with regarding the whole Critique as the doctrine of method of metaphysics. Since cognitions belonging to a science must already be established in order for a doctrine of method to perform its task, the Transcendental Doctrine of Method requires that at least some doctrinal parts of metaphysics be established in the Transcendental Doctrine of Elements. I argue that this has important consequences for how we should depict the relationship between the critique of pure reason and transcendental philosophy.

Scepticism is the second approach to metaphysics that Kant considered an alternative to his ‘critical’ investigation. It is David Hume who plays the role of the paradigmatic representative of this viewpoint. I begin by analyzing three different readings of Kant’s understanding of Hume’s scepticism about causality. Hume’s scepticism is seen as posing a challenge to natural science and ordinary knowledge, as a problem that puts into question the possibility of general metaphysics, or as a ‘dialectical’ form of scepticism primarily directed against special metaphysics. I suggest that the first reading is implausible. I argue that the second and third readings are compatible once one distinguishes between the perspectives of transcendental philosophy and the critique of pure reason, respectively. Finally, I show that one objection that has been raised against the third reading can be silenced if we interpret Kant’s reading of Hume from the standpoint of his history of pure reason.

Chapter 6 is dedicated to reconstructing how Kant sets limits to the validity of the categories. In my reading, the argument that establishes these limits belongs to the negative part of the critique of pure reason. I first find confirmation that it is correct to distinguish between a positive and a negative argument concerning the validity of the categories, the former belonging to transcendental philosophy and the latter to the critique of pure reason, in three different texts by Kant: the transcendental deduction of the categories, the Metaphysical Foundations of Natural Science and On the Use of Teleological Principles in Philosophy. However, since these texts provide different pictures concerning how the two arguments are related to one another, I analyze in which sense the negative argument depends on the positive one by reconstructing relevant passages in the B-deduction.

In this chapter, I reconstruct the metaphysical deductions that, in my account, Kant presents in the Aesthetic, Analytic and Dialectic, respectively. I read metaphysical deductions as accomplishing the first task of transcendental philosophy as it is established in the Critique of Pure Reason, namely the task of cataloguing pure root concepts (Stammbegriffe) for the cognition of objects and to track their origin. I argue that the metaphysical deductions do not simply assume a distinction between different faculties. Rather, they contribute to establishing this distinction by identifying the origin of the root concepts they clarify and catalogue. Moreover, I show that Kant does not follow a univocal model in the different deductions. Rather, his approach is pluralistic.

In the Architectonic of Pure Reason, Kant claims that a condition for attaining the status of science is that a body of cognitions achieves architectonic unity. The chapter clarifies what this is and argues that this is more than mere systematicity. While there could be different ways of systematically ordering a body of cognitions, there is only one such order that bestows architectonic unity to it. Architectonic unity is achieved when the ‘idea’ of a science given a priori by reason is realized in an actual body of cognitions. I read this ‘idea’ as the correct description of the body of cognitions that form a science and its parts–whole relationships. In a further step, I discuss the ‘idea’ that is a candidate for providing unity to metaphysics. Kant identifies two candidate ‘ideas’ according to which metaphysics can be understood. Metaphysics can be construed according to either the ‘school concept’ (Schulbegriff) or the ‘worldly concept’ (Weltbegriff) of philosophy. I argue that it is only according to the ‘worldly concept’ that metaphysics can attain architectonic unity and become a science.

Famously, in the Canon of Pure Reason, Kant present a practical argument to the effect that our beliefs in God and immortality are justified. I argue that reading the Critique of Pure Reason as the doctrine of method of metaphysics provides a straightforward explanation of the systematic place of Kant’s practical argument in the Canon. Customarily, the relevance of the Critique for the practical part of metaphysics is restricted to proving the theoretical undecidability of God and immortality, but the Canon clearly goes beyond establishing that. According to its positive task as the doctrine of method of metaphysics, the Critique must establish that metaphysics can achieve ‘architectonic unity’. I argue that showing that this unity is possible for metaphysics requires showing that there is conceptual space for coherently accommodating our commitment towards the existence of God and immortality within it.

The introductions provides a presentation of the books main claims and an overview of the chapters.

While Chapter 3 was dedicated to metaphysical deductions, this chapter reconstructs transcendental deductions, which I take to accomplish the second task of transcendental philosophy as it is established in the Critique of Pure Reason. Transcendental deductions are tasked with determining that root concepts (Stammbegriffe) have objective validity. In a way similar to my analysis of metaphysical deductions, I identify a transcendental deduction of space and time in the Aesthetic, a transcendental deduction of the categories in the Analytic and a transcendental deduction of ideas in the Dialectic. However, objective validity does not mean the same in all these cases. I take it that the main sense in which Kant uses the term is the following: concepts have objective validity when through them we cognize something that really pertains to objects. This is not the sense of objective validity that Kant uses with respect to ideas. In this case, claiming that ideas are objectively valid means attributing to them what I call the ‘practical’ and the ‘indirect’ validity of ideas. I argue that transcendental deductions only establish positive results regarding the validity of the root concepts and are not tasked with determining limits of this validity.