Chapter 4 develops Merleau-Ponty’s perspectival account of experience. It shows how Merleau-Ponty’s claim that perception has a different structure to what he calls ‘objective thought’ can be derived from his interpretation of Kant’s paradox of symmetrical objects. It looks at how this difference in structure leads to Merleau-Ponty’s distinctive accounts of perspectival depth and orientation in space, before returning to Kant to show how Merleau-Ponty’s account of perception as having a figure-background structure leads to substantial divergences from Kant’s account of the constitution of the object (in doing so, it reconstructs a sustained argument against Kant’s transcendental deduction from fragmentary comments throughout Merleau-Ponty’s work). It also shows that the model of determination developed by Merleau-Ponty, while relying on context, differs significantly from Hegel’s account of determination, and supplements deficiencies in Sartre’s account.

To understand why rational thinkers, according to Kant, are naturally led to accept the Supreme Principle as true, we must answer two questions: why does the Logical Maxim have to become a principle of pure reason – that is, why is it rationally necessary to make regulative use of the Supreme Principle? And why does this lead to the illusion that the Supreme Principle is an objectively valid constitutive principle (i.e., a true descriptive statement about everything there is)? Chapter 5 offers answers to these questions. The latter question in particular requires a discussion of Kant’s account of transcendental illusion and the role of transcendental realism in bringing about this kind of illusion. The central idea is that transcendental realism implies that there is a correspondence between reason and reality; therefore, a tacit commitment to transcendental realism can explain why regulative principles of reason will naturally be taken to be constitutive principles that are true descriptions of reality itself. Even though transcendental realism is a weighty metaphysical claim, it can plausibly be attributed to common sense or ‘universal human reason.’ The chapter closes with a discussion of why, according to Kant, the Supreme Principle is valid for things in themselves.

Chapter 7 turns to the first two of the three metaphysical disciplines whose inferences and conclusions Kant discusses in the Transcendental Dialectic, namely, rational psychology and cosmology. We show how the four transcendental paralogisms and the arguments underlying the four antinomies of pure reason can be read as ‘necessary inferences of reason’ and how they result in the corresponding transcendental ideas. The chapter considers the paralogisms and the psychological ideas, discusses the role of transcendental realism in the paralogisms, looks at the derivation of the cosmological ideas and the four antinomies, and reconstructs the role of transcendental realism in the antinomies. In doing so, we concentrate on those aspects that are relevant to understanding how Kant develops his Rational Sources Account in the Transcendental Dialectic.

Chapter 9 examines Kant’s critique of metaphysics in the Critique of Pure Reason. We discuss transcendental realism and its relation to transcendental idealism and then argue that rejecting transcendental realism does not presuppose transcendental idealism. Next, we will see that even on its most general level, Kant’s critique of metaphysics does depends not on transcendental idealism but on the much more specific claim that human cognition is limited to sensible objects. Finally, we will distinguish between different interpretations of Kant’s account of transcendental ideas and argue for a radical reading according to which, when viewed in a purely speculative context, ideas of reason fail to represent (really possible) objects, which accounts for the third level of Kant’s critique of metaphysics. Our result will be that Kant develops a challenging critique of speculative metaphysics that does not presuppose his transcendental idealism.

The Introduction explains the two major aims of the book. First, the book will offer a novel interpretation of the Transcendental Dialectic that isolates its constructive side, Kant’s account of the rational sources of speculative metaphysics (concerning the soul, the world as a whole, and God), and distinguishes it clearly from its destructive side, Kant’s critique of this kind of metaphysics. Second, it will reconstruct, and where possible defend, a Kantian account of the rational sources of metaphysical thinking. In particular, it will argue that Kant is right in claiming that metaphysical speculation arises naturally out of principles that guide us in everyday rational thought. As the book will argue, Kant gives us good reason to think that discursivity, iteration, and striving for completeness are fundamental features of rational thinking and that, taken together, they give rise to a specific kind of metaphysical speculation. This is a distinctive and original perspective on metaphysics that deserves to be taken seriously in the current metaphysical and meta-metaphysical debates.