In this book I have argued that Kant's central argument in the B-Deduction can be summarised in the form of two premises and a conclusion, as follows.

1. α. All our cognition must involve a spontaneous synthesis.

2. β. If our cognition involves a spontaneous synthesis then this synthesis must be governed by the categories.

3. ∴ The categories make our cognition possible.

Or, as Kant himself puts this argument in a letter to J. S. Beck (20 January 1792): ‘Since composition … cannot be given but must be produced, it must rest on the pure spontaneity of the understanding in concepts of objects in general’ (11:315–16). In chapter 2 of this book I sketched out Kant's reasoning for his second premise (β), and in the previous chapter I argued that § 16 of the B-Deduction contains Kant's master argument for his first premise (α). This chapter continues with a reading of the remaining sections of the B-Deduction that contain Kant's main line of argument, namely, §§ 17–20 and § 26.

SECTION 17: SYNTHESIS AND OBJECTS

In § 17 of the B-Deduction, entitled ‘The principle of the synthetic unity of apperception is the supreme principle of all use of the understanding’, Kant discusses some of the further consequences of the conclusions reached in § 16. An examination of § 17 will provide further textual evidence for my interpretation of Kant's discussion in § 16 and, indeed, for my interpretation of the argument of the B-Deduction as a whole.