Kant’s contention that there are exactly twelve pure concepts of the understanding (i.e. categories) and that these can be identified with the aid of a number of distinctions traditionally drawn by logicians among formally different types of judgement figures among the more notorious claims set forth in the Critique of Pure Reason. It attracted fierce criticism early on and has become known as the problem of the completeness of the Table of Judgements (and, closely related, the Table of Categories). Part of the problem is that, although Kant says he proves the completeness of his table, it is difficult to locate such a proof in the text. At best, its presentation is highly condensed; at worst, no such proof is given. But while scepticism has been the prevailing attitude, repeated attempts have been made to reconstruct a rigorous completeness proof on Kant’s behalf and locate it in the text.Footnote ¹ Dennis Schulting’s book Kant’s Deduction and Apperception: Explaining the Categories seeks to continue this tradition. It offers a reading of central passages of the first Critique, which aims to uncover in them a successful argument to the effect that all twelve concepts on Kant’s Table of Categories are indeed pure concepts of the understanding; that is, concepts which are not derived from experience, but which ‘the understanding contains in itself a priori’ (A80/B106).Footnote ²

Commentators who address the completeness problem, notably Reinhard Brandt and Michael Wolff, tend to hold that the key is to be found in Kant’s attempted derivation of the Table of Judgements and accordingly focus their investigations on the theory of judgement Kant offers in the lead-up to his presentation of the table (A67/B91–A70/B95). By contrast, Schulting follows Klaus Reich in thinking that we should take Kant at his word when he says that the categories ‘are all derived from the principle of the transcendental unity of apperception’ (B142). As a result, the book’s focus is on the Transcendental Deduction (TD), where the doctrine of apperception is first introduced and where Schulting locates the derivation of the categories. Unlike Reich, however, who seeks to derive the Table of Judgements from the doctrine of apperception, Schulting is exclusively concerned with the categories.Footnote ³ The main thesis of the book, then, is that Kant offers a derivation of the categories from the principle of apperception; that is, the principle expressed in the famous opening statement of §16, ‘The: I think must be able to accompany all my representations’ (B131). This thesis is supported by a close reading of the first half of the B-Deduction, where, Schulting contends, Kant gives this derivation, albeit in highly condensed fashion.

As part of his defence of the derivation thesis, Schulting articulates three additional exegetical commitments regarding the B-Deduction, which jointly make his reading distinctive and original. The first two of these are

Third, Schulting offers an original account of the structure of Kant’s argument in the TD, which seeks to chart a middle path between those readings that construe Kant’s argument as ‘progressive’ (e.g. Strawson Reference Strawson1966 and Guyer Reference Guyer1987) and those that see it as ‘regressive’ (most notably, Ameriks Reference Ameriks1978). As a result, the book in effect provides a detailed interpretation of the first half of the B-Deduction, which it develops in part by critically discussing a variety of prominent competitor readings. Although Schulting contends that these claims all form a package (indeed, that the TD as a whole cannot be understood in isolation from the derivation of the categories), the discussion of Reciprocity in particular can be isolated from the derivation issue.

Schulting proceeds by first articulating and defending central aspects of his reading, thereby putting into place a particular interpretation of the doctrine of apperception and the proof-structure of TD (chapters 2–5), before developing arguments that purport to show, for each of the twelve categories, that it is analytically contained in the apperception principle (chapters 6–9). The concluding chapter offers a defence of Reciprocity.

Prima facie, the derivation thesis faces the objection that, with the exception of §26, Kant does not discuss individual categories in the B-Deduction and speaks of them only collectively (sometimes using the phrase ‘the category’ as a collective noun; see B131, B144, B146, B158). This might be taken to indicate that Kant’s argument proceeds at a level of abstraction at which it is not necessary (and perhaps not possible) to distinguish between different categories and that therefore the Deduction is simply not the place to look for a derivation in Schulting’s sense. Schulting acknowledges the textual evidence, but insists that ‘the thrust of the argument in TD is such that it accounts, in the typical mode of a prima philosophia, for each of the categories as one of the grounding functions of transcendental apperception as the source of objectively valid thought’ (p. 4).

For each of the twelve categories Schulting formulates the derivation thesis as an instance of the following schema: ‘Category F pertains to the identity of discursive thought and hence is analytically derivable from it’ (see p. 121 and passim). This needs a bit of unpacking. First, Schulting speaks of discursive thought here, rather than experience, because he holds that the first half of the B-Deduction – hence, the doctrine of apperception – pertains to the nature of discursive thought as such, not just to the deployment of discursive thought in the generation of experience. So the derivation thesis is not equivalent to the claim that the categories are conditions of the possibility of experience, and establishing it is only one part of Kant’s agenda in the Deduction.Footnote ⁴ Its upshot is rather that any finite rational thinker, even one whose forms of sensibility are not space and time, will possess the categories.

Second, Schulting’s formulation might be taken to imply that the relevant category figures in an account of the intensional content of the concept <faculty of discursive thought>. But this would not cover the modal categories, and it is not how Schulting understands the claim. Rather, he takes the starting point of the derivation to be the ‘fact of discursive thought’ (p. 120), which is apprehended in the immediate consciousness of one’s existence as a thinker that is expressed by actual tokenings of ‘I think’. Talk of the identity of discursive thought, then, must be understood as including commitment to the existence of discursive thought.

How, then, are the twelve derivation theses arrived at? Schulting presents a number of complex arguments, each of which would warrant extensive comment. For reasons of space, however, I will consider only the categories of substance and cause. By way of background, Schulting contends that the power of discursive thought is, fundamentally, the power to generate synthetic unity of apperception in a representational manifold. But, by Rigorous Coextensivity, the power to generate synthetic unity of apperception is identical with the power to think of oneself as the identical subject of all of one’s cognitively significant representations. The following passage then summarizes the main idea driving the derivation of these two categories:

As claimed in this passage, the power to generate synthetic unity of apperception in a manifold cannot be described without making use of the concepts <substance-accident> and <cause-effect>. Accordingly, ‘[t]he category of “substance” pertains to the identity of discursive thought and hence is analytically derivable from it’ (p. 147); the same holds for the category <cause-effect>.Footnote ⁵

The starting point here is clearly sound, namely, that the power of discursive thought is, fundamentally, a power to generate synthetic unity of apperception. We should also grant, if only for the sake of argument, the claim regarding the identical subject of representation and the claim that the self-ascription of thoughts employs the concepts of substance and cause. However, in what sense, if any, does this amount to a derivation of these categories from apperception?

Giving a derivation of the categories might be taken to involve showing one or more of the following:

1. Purity: The concepts in question originate purely in the understanding (where this means that these concepts are necessarily possessed by anyone who possesses the power of understanding).

2. C ompleteness: These concepts are the only concepts that so originate.

3. Objective Validity: Necessarily, all possible objects of finite rational cognition instantiate these concepts (in the complex disjunctive way Kant claims for his categories).

I noted above that Schulting is not concerned to establish Completeness. Elsewhere he makes clear that he takes both Purity and Objective Validity to be at issue.Footnote ⁶ Does his derivation succeed in demonstrating these?

Regarding Purity it might be objected that the fact that some concept F is deployed in a theoretical account of a capacity does not show that a subject possessing this capacity possesses F. At most, it shows that the theorist giving the account possesses F. Schulting could respond that the reason why these concepts must figure in an account of the power is that they are deployed in exercises of the power. I believe he is in fact committed to this, even though his formulation of the derivation does not make this clear. But Schulting explicitly affirms that all acts of synthesis are acts of judgement and that the categories are ‘the ways in which manifolds of representations in intuitions are determined’ (p. 90), in acts of judging, so as to constitute representations of objects. It appears to be his view, then, that to possess a categorial concept is to possess the power to determine sensible manifolds in one of these ways. If we add Rigorous Coextensivity to this, Schulting has a plausible claim to establishing Purity.

Still, one might insist that this line of thought leaves it unclear why possession of the power to generate synthetic unity in sensible manifolds entails the possession of certain concepts. What kind of power is this such that it is appropriately thought of as a power whose exercise involves the deployment of concepts, and in particular categorial concepts? Since the categories ‘consist solely in the representation of this … synthetic unity’ (A79/B104), saying that judging involves the deployment of categorial concepts suggests that judgements not just de facto generate unity, but that this unity is also represented by the thinker; and indeed that the kind of unity that judgements generate is one to which it is essential that it be represented – that there is no such unity of consciousness without a consciousness of this unity. If this is right, then it is clear why exercises of the power to generate synthetic unity must involve the deployment of categorial concepts. But then this is also a reason for thinking that – pace Schulting – Purity, at least, cannot be established by consideration of apperception alone, in isolation from the question how the categories relate to the logical forms of judgement.Footnote ⁷

As far as Objective Validity is concerned, Schulting sees Reciprocity (that is, the claim that synthetic unity of apperception of a manifold is both necessary and sufficient for this manifold’s possessing objective purport) as essential to this aspect of the derivation, and rightly so. Consequently, Kant can have a plausible case for establishing Objective Validity only if Reciprocity can be defended from the charge that Kant’s argument for Reciprocity is invalid, as raised by e.g. Strawson and Guyer. Schulting offers such a defence on Kant’s behalf, and this is a valuable contribution of the book – one that should be of interest even to those who are sceptical about the derivation thesis. In a nutshell, the defence is that Strawson and Guyer incorrectly read the phrase ‘my representations’ in Kant’s statement that ‘[the] “I think” must be able to accompany all my representations’ (B131) as referring to all representations of which I am the bearer. By contrast, Schulting takes the phrase to pick out only those representations that possess objective purport. But if this is right, then Kant has a valid argument for Reciprocity. While this does not yet show that Schulting’s derivation establishes Objective Validity, it neutralizes one significant obstacle.Footnote ⁸

Kant’s Deduction and Apperception provides a rich and nuanced discussion of topics that lie at the heart of Kant’s project in the first Critique, many of which I have not been able to comment on here. Schulting’s position is original and the discussion throughout is informed by an impressive command of both primary texts and secondary literature. Although the considerations I have raised concerning Purity and Objective Validity indicate that there are reasons for doubting the success of Schulting’s arguments for the derivation thesis, there is much to be learned from them. More generally, the Reich-inspired project he undertakes is one that deserves more attention than this approach has traditionally received, at least in Anglophone Kant commentary. Anyone interested in the categories, the Transcendental Deduction, or the doctrine of apperception will benefit from reading this book.