BRYAN HALL | The Post-Critical Kant: Understanding the Critical Philosophy through the Opus Postumum | Routledge 2015


By Bryan Hall 

I would first like to thank Hein van den Berg and Jeffrey Edwards for their detailed comments on my work as well as for their own valuable contributions to the scholarship on Kant’s Opus postumum. I appreciate the opportunity to respond to both of them in (virtual) print. Thanks also to Kenneth Westphal for his thoughtful reflections on his own work as well as for his concerned diagnosis of what ails modern academia (I was happy to see that my work is more a symptom than a cause). I respond to them in turn.

Response to Hein van den Berg

Although we represent different strands of interpretation, in what follows, I hope to show that there is some common ground between our two approaches. Van den Berg’s approach continues a strand of interpretation first promulgated by Hansgeorg Hoppe (see my The Post-Critical Kant, henceforth PCK, pp. 13–15). Unlike my own approach, Hoppe’s interpretation has the advantage of giving a straightforward reading both of the gap problematic and its relationship to the transition project. Hoppe claims that the gap lies between the Metaphysical Foundations of Natural Science and empirical physics. Bridging this gap requires a transition from the one to the other, i.e. showing how the pure natural science articulated in the Metaphysical Foundations can be extended to empirical physics. The goal of the transition is to establish the scientific status of empirical physics (Hoppe 1969:69–81).

Van den Berg follows in the footsteps of Hoppe with respect to the purpose of Kant’s transition. Specifically, for van den Berg, the transition project aims to establish the systematic unity of physics. Even so, van den Berg acknowledges that effecting this transition cannot fill a gap in Kant’s Critical philosophy. This is a point that I make in PCK as well. In his September 1798 letter to Christian Garve, with which I begin PCK, Kant says that without the transition “a gap will remain in the critical philosophy” (Br, AA 12:257). A month later, in a letter to Johann Kiesewetter, Kant says that with the completion of the transition, “the task of the critical philosophy will be completed and a gap that now stands open will be filled” (Br, AA 12:258). As I note in PCK, Kant’s desire to apply the Critical philosophy to the domain of empirical physics does not constitute a gap within the Critical philosophy itself (p. 15).

As van den Berg remarks, I believe that the gap lies in what Kant calls the “transcendental part” of the metaphysics of nature (MAN, AA 4:469–70). In the Critique of Pure Reason, Kant claims that this transcendental part comprises “the understanding and reason itself in a system of all concepts and principles that are related to objects in general” (A845/B873). In other words, the transcendental part of the metaphysics of nature is the Transcendental Analytic from the Critique. One can look to Farrago 1 of OP, which was written in December 1798, not long after his letters to Garve and Kiesewetter, for evidence that Kant believes the gap is in the transcendental part of the metaphysics of nature. There, Kant claims that the transition project “is designed to fill what is still a gap in the pure doctrine of nature and generally in the system from a priori principles, and so toward accomplishing completely my metaphysical work” (OP, AA 21:626; trans. mine). This passage from Farrago 1 is consistent with the idea that the gap lies in the Transcendental Analytic. As I argue in Chapter One of PCK, the gap lies in a specific part of Kant’s “system from a priori principles”, viz. the Analogies of Experience. Although van den Berg does not specifically challenge the way in which I locate the gap in Kant’s Critical philosophy, he does offer Michael Friedman’s account of the gap as an alternative approach that is consistent with his view of the transition (i.e. where establishing the systematic unity of physics would fill a gap in the Critical philosophy). Before moving on to what van den Berg and I share in common, it might be worth examining the problems with Friedman’s account of the gap.

Friedman believes that the gap arises from a failure to coordinate the different methods of the Metaphysical Foundations and the Critique of the Power of Judgement. Whereas the Foundations relies on the constitutive function of determining judgement, which begins with transcendental principles and moves downward to the metaphysical principles of the doctrine of body through which these transcendental principles are applied to the empirical concept of matter, the Critique of the Power of Judgement relies on the regulative capacity of reflecting judgement, which begins with particular empirical facts and moves upwards to these transcendental principles. This problem of methodological coordination reveals a gap in the Critical philosophy (Friedman 1994:254–6). Although I think there are philosophical problems with this view (e.g. contra Friedman, the results of determining judgement seem to place a constraint on the speculative scope of reflective judgement), there are more significant textual worries (PCK, pp. 17–19). Specifically, Kant never discusses the distinction between determining and reflective judgement (much less the potential problem of coordinating them) at any length in the Opus postumum. If coordinating these two methods constituted the gap, one would think Kant would spend more time talking about them in the Opus postumum

Although van den Berg claims that I offer a “unified” interpretation of the Opus postumum, a better adjective would be “developmental”. Using textual evidence from the Opus postumum, I argue that Kant’s view on the transition project changed over time. In his commentary, van den Berg points to the Oktaventwurf from 1796 in support of his view of the transition. There, Kant is very much concerned with topics in physica specialis (e.g. density, cohesion, etc.) and says that the transition aims to establish

how it is possible for us to collect and order the elements of a doctrine of nature to be based on experience, and to arrange them with the completeness required for systematic classification. (OP, AA 21:403)

This view of the transition is also consistent with Kant’s proclamation in the Preface to the Critique of the Power of Judgment from 1790 that he is bringing his “entire critical enterprise to an end” and that he will “proceed without hindrance to the doctrinal part” which will include the “metaphysics of nature and of morals” (KU, AA 5:170). The above quote from the Opus postumum makes it clear that Kant was concerned, in the Oktaventwurf, with completing a doctrine of nature, i.e. the metaphysics of nature that he promises to complete after the publication of the Critique of the Power of Judgement. There is evidence from Kant’s correspondence from Kiesewetter, furthermore, that Kant’s plan for a transition project goes back to 1790 (see PCK, p. 4 and Br, AA 12:23). If Kant’s transition project in the Oktaventwurf (the earliest version available) reflects his original plan for the transition project, it dates back to a time (the publication of the Third Critique) when Kant thought the Critical philosophy was complete. Although I believe that Kant never gave up on completing his doctrinal task (PCK, p. 147), I do believe that his conception of both the transition project and physics itself broadened over time. Although it is not initially connected with the gap problematic, once Kant discovers the gap, he redescribes his transition project to bridge it.

One can see just how much Kant’s transition project has broadened in scope by examining the Übergang [Transition] section of the Opus postumum written between May and August of 1799. Kant entitles one draft:

The existence of caloric as the highest principle of the transition from the metaphysical foundations of natural science to physics. (OP, AA 21:600; trans. mine)

Kant himself downplays the role the caloric might play in explaining specific physical phenomena, holding instead that its existence is demonstrable as a condition for experience. As he says,

Caloric is actual: it is not a material feigned for the sake of the explanation of certain phenomena, but rather, a material demonstrable from a universal principle of experience […]. (OP, AA 22:551)

Putting aside what Kant means by “caloric” (something I shall deal with when responding to the other critics), we can see that Kant’s plan for the transition has broadened beyond the doctrinal task of the Oktaventwurf to the conditions of experience itself. As he says:

If it can be proven that the unity of the whole of possible experience is founded upon the existence of such a material [ether] (with its stated properties) so its actuality is also proven, not by experience but rather a priori for experience, merely from the conditions of its bare possibility. (OP, AA 21:572; trans. mine)

If the conditions of experience, as articulated in the Critique of Pure Reason, are themselves incomplete, this would expose a gap in the Critical philosophy itself, one that would be potentially filled by a redescribed transition project. Whereas the transition project articulated in the Oktaventwurf is arguably consistent with the doctrinal task he articulates in the Preface to the Third Critique, the transition project as articulated in the Übergang section is not insofar as it shows that the Critical philosophy is not complete. This is not at all surprising, however, insofar as what stands between the Oktaventwurf (1796) and the Übergang (1799) are Kant’s letters to Garve and Kiesewetter (1798), where he admits that there is a gap in the Critical philosophy that the transition must bridge.

I should also note that Kant comes to redefine ‘physics’ itself over the course of the Opus postumum. In Convoluts 10–11, which were written immediately after the Übergang section and completed sometime in April of 1800, Kant defines ‘physics’ as “empirical cognition in a system” and the concept of the caloric plays a vital role in physics since it serves as the “formal principle of the unification of the moving forces in the subject for the unity of experience” (OP, AA 22:339; trans. mine). In other words, physics consists in the unity of experience as realised in this system of forces. As Kant says:

Physics is the doctrinal system of the moving forces of matter, insofar as it can be exhibited (exhiberi) in experience. (OP, AA 22:511)

Later, he describes “physics as the universal doctrine of experience” (OP, AA 22:488). This is broader than natural history (physica specialissima), broader than the study of the particular properties of bodies (physica specialis), and even broader than study of the universal properties of matter (physica generalis). The proper subject matter of physics has expanded to include the (material) conditions for the possibility of unified experience. When one is talking about the conditions for the possibility of experience, however, one is back in the domain of the Critical philosophy itself and not simply its doctrinal application (e.g. the physica specialis of the Oktaventwurf).

In sum, I can wholeheartedly agree with van den Berg that Kant’s plan for a transition project has to do with establishing the systematic unity of physics. For Kant, however, the scope of ‘physics’ itself broadens and deepens over time. Once we get to Convoluts 10–11, physics deals not only with issues like density, cohesion, and the like (the explanation of physical phenomena), but with the conditions for the unity of experience itself. While the transition was not originally concerned with filling a gap in the Critical philosophy, once Kant discovered a gap in the Critical philosophy, he redescribed ‘physics’ and with it the transition project so that he would be able to fill this gap.

Now that I have outlined some of the main differences between van den Berg’s interpretative approach and my own, I am in a position to respond to the concerns he raises in connection with my methodological principles.

First, when it comes to textual consistency, if Kant does not recognise a gap in his Critical philosophy (1798) until after he writes the Oktaventwurf (1796), it should not be surprising if an interpretation of the gap problematic does not help us in understanding the passages from the Oktaventwurf that are devoted purely to scientific topics.

Second, when it comes to making Kant consistent with himself, I do not offer a “unified interpretation of the entire work” (van den Berg), but rather a developmental interpretation that accepts that Kant changed his mind over time with respect to the nature of his transition project (PCK, p. 12). Although this does not dispel some of the synchronic inconsistencies that one finds in the text, it does dispel a good number of the diachronic ones. The synchronic inconsistencies (e.g. Kant claims in the Übergang section that the caloric is a formal and a material condition for experience) must be resolved by the interpretation itself (PCK, p. 25).

Third, when it comes to an interpretation being philosophically plausible, I appreciate van den Berg’s concern about authority. Since both of us find Kant’s scientific speculations in the Oktaventwurf suspect, however, I would suggest that an interpretation that does not make these speculations central to Kant’s project should be preferred to one that does. This being said, I should have added a ceteris paribus clause to each of my methodological principles. An interpretation that is philosophically plausible should be preferred to one that is not assuming the other methodological principles have been met. I believe that my interpretation clears this bar.

Finally, as long as I am not asked to bring it to fruition, I can wholeheartedly endorse van den Berg’s call for a new edition of the Opus postumum that includes the features that he mentions. In this respect, we echo a call across history (Krause and later Adickes) for an edition of the Opus postumum that is more appropriate for scholarly study (PCK, p. 8).

Response to Jeffrey Edwards

Although Edwards’s general summary of my view is accurate and we certainly agree on the centrality of Kant’s Ether Deduction (from the Übergang section of the Opus postumum) for understanding (at least an important phase of) Kant’s project, there are nevertheless many differences between my view and his own. This is true both of the way he portrays the details of my view as well as the interpretative approach he adopts to argue against it. In what follows, I shall use my principles of interpretation (which van den Berg has discussed at some length) to explain why my interpretative approach should be preferred to Edwards’s own. I shall focus, in particular, on three areas of interpretative difference:

  1. the relationship between the transition project and the gap problematic,
  2. the nature of the purported gap, and
  3. how my version of the gap problematic can be resolved.

As the opportunities arise, I shall also correct mistakes in the way that Edwards has characterised the details of my view.

Ad 1. Edwards grants Förster’s timeline for the transition project (dating its origins to 1790), but unlike Förster, Edwards does not believe that Kant changes his mind with regard to the nature of the transition project over time. He also believes that “transition and gap designate two sides of the same architectonic coin”. Consequently, Edwards believes that Kant does not change his view on the gap in his system of Critical philosophy, i.e. that this gap can be traced back to 1790 as well. Following Tuschling, Edwards believes that the gap in Kant’s system of Critical philosophy stems from Kant’s dissatisfaction with his dynamical theory of matter in the Metaphysical Foundations. Contrary to Förster’s own intention, Edwards argues that the former’s timeline enables “us to understand how Kant’s transition project is inseparably linked to the 1780’s revision in his dynamical theory of matter”.

In the Introduction to PCK, I take some time to explain why I think that other interpretative approaches (including the one Edwards endorses) fail to satisfy the interpretative principles I set out in the book (PCK, pp. 13–23). My first interpretative principle claims that a good interpretation should be maximally consistent with the text. I begin my book by quoting the Preface to the Critique of the Power of Judgement (1790), where Kant claims that he is bringing his “entire critical enterprise to an end” (KU, AA 5:170). Assuming that Kant’s dynamic theory of matter from the Metaphysical Foundations is part of his “critical enterprise”, Edwards’s interpretation would require us to accept that Kant had detected a serious gap in his Critical philosophy at the same time that he is saying it is complete (PCK, p. 15). This violates my second interpretative principle insofar as it imputes contradictory views to Kant in 1790.

I do not think that Kant’s concerns with his dynamical theory of matter in the Metaphysical Foundations, however, pose a problem for the completeness of the Critical philosophy. Scholars (including Tuschling 1971:46–56) point to a circularity in Kant’s theory of matter which was diagnosed by J.S. Beck in a letter from 1792 and can be traced back to claims that Kant makes in the General Remark on the Dynamics in the Foundations (see PCK, pp. 9–10). Kant considered the General Remark, however, to be speculative and not part of the special metaphysical natural science that he develops in the rest of the book (MAN, AA 4:524). In order for a failure in the General Remark to open up a gap in the Critical philosophy, Kant would have had to change his mind with regard to the scope of the Critical philosophy. Again, if Edwards’s timeline is granted, Kant would have had to recognise this gap while simultaneously claiming that the Critical philosophy is complete (violating my second interpretative principle). It does not help, furthermore, that Kant does not return to the circularity issue explicitly in the Opus postumum itself (Friedman 1992:223n8).

Admittedly, Tuschling also has concerns with Kant’s argument for the first proposition of the Dynamics of the Foundations, viz. Kant’s attempt to prove the existence of an original moving force in matter from the presence of mere motion (Tuschling 1971:96–8). That Kant also had this concern is substantiated by the first page of the Opus postumum, which contains a very critical anonymous review of the Foundations from the Göttingische Anzeigen, making the same point, and copied out in Kant’s own hand (OP, AA 21:415). Could a serious defect in the main part (not the General Remark) of the Foundations open up a gap in the Critical philosophy?

Following Tuschling, I view Farrago 1–4 of the Opus postumum (1798) as central for understanding Kant’s view of the gap problematic. Likewise, I also agree with Tuschling that the gap is in the ‘transcendental principles’ of the Critique of Pure Reason (Tuschling 1971:182). The problem with Tuschling’s approach, however, is that it requires a failure in the Foundations to open up a gap in the Critique of Pure Reason. At the beginning of the Foundations, Kant clearly distinguishes the “transcendental part” of the metaphysics of nature (Critique) from its “special part”, i.e. the Foundations as a special metaphysical natural science (MAN, AA 4:469–70). If the gap arises from a failure in the Foundations, then the special part really belongs to the transcendental part, contrary to Kant’s intention. Kant also holds that the metaphysical doctrine of body (Foundations) should be dealt with in an “isolated system” distinct from general metaphysics (Critique) and that doing so “does not impair the completeness of general metaphysics” (MAN, AA 4:477). This suggests that any failure in the Foundations, as an isolated system, would not have an impact on the completeness of the Critical philosophy as articulated in the Critique of Pure Reason. This is a serious textual problem for Tuschling’s interpretation (and by extension Edwards’s interpretation) which violates both my first principle of interpretation (textual consistency) as well as my second principle of interpretation insofar as it makes Kant inconsistent with himself.

My own view of the relationship between the transition project and the gap problematic avoids the above concerns. I have already explained (with textual support) in my response to van den Berg why I think Kant’s systematic aims for the transition project change over time. By holding a developmental (rather than static) view of Kant’s transition project, one can make sense of the texts that Edwards ignores while also avoiding the contradictions that Edwards’s interpretation entails. This puts us in a position to correct Edwards’s most significant misinterpretation of my book. It is simply false that “Hall emphatically denies that this gap has directly to do with the problem of working out a transition from the metaphysical foundations of natural science to physics”. In fact, what I say (repeatedly) is that “far from being separate issues, Kant’s redescribed transition project and the gap problem are intimately connected” (PCK, p. 148; see also pp. 18, 21, and 24–6). The key word here is “redescribed”. Although I think that Kant’s transition from the metaphysical foundations of natural science to physics is supposed to fill the gap in his Critical philosophy, there is very strong reason to believe that Kant’s view of the scope of ‘physics’ changed over time (see my response to van den Berg) and that what he means by ‘metaphysical foundations of natural science’ changes as well over the course of the Opus postumum (specifically with regard to its transcendental part). When it comes to the latter,  Tuschling himself claims that when Kant talks about the ‘metaphysical foundations of natural science’ in the Opus postumum, he does not mean the same thing by this phrase as when he published the Metaphysical Foundations in 1786 (Tuschling 1971:182). Edwards fails to note this crucial point when comparing Tuschling’s interpretation to my own.

Edwards describes the transition as “exploring the consequences of assigning a central role to physical æther (or caloric) in the dynamical explanation of natural phenomena”. As I noted in my response to van den Berg, although this characterisation of the transition project is certainly an accurate representation of Kant’s view in the Oktaventwurf (1796), his ambitions for the transition increase after his acknowledgement of the gap in his 1798 letters to Garve and Kiesewetter. Specifically, Kant comes to believe that the transition is necessary to complete the conditions of possible experience where this experience is understood as unified. Although I already cited a passage from the Übergang section (1799) to illustrate this point when responding to van den Berg, let me cite another passage from Convolut 10 of the Opus postumum (1800) that makes a similar point:

The transition from the metaphysical foundations of natural science to physics is therefore not an aggregation of empirical representations with consciousness, rather the concept of the synthetic unity of these representations for the possibility of experience which at any time is thought as a system of empirical representations (not an empirical system for that would be a contradiction). (OP, AA 22:359; trans. mine)

While Kant is writing the Selbstsetzungslehre (doctrine of self-positing) in Convolut 7 of the Opus postumum (1800), he starts to formulate the transition in still different ways. Whereas up to this point the transition had been characterised as between the metaphysical foundations of natural science and physics, Kant now oscillates between this formulation and two others. One describes the transition as between the metaphysical foundations of natural science and transcendental philosophy (OP, AA 22:129). The other describes the transition as progressing from the metaphysical foundations of natural science to transcendental philosophy and then finally to physics (OP, AA 22:86). The situation becomes even more complicated in the final fascicle, Convolut 1 (1801), where Kant imagines the transition as a multi-part project that comprises:

(1) Transition from the metaphysical foundations of natural science to physics. (2) Transition from physics to transcendental philosophy. (3) Transition from transcendental philosophy to the system of nature and freedom. (4) Conclusion. Of the universal connection of the living forces of all things in reciprocal relation: God and the world. (OP, AA 21:17)

Although Convolut 1 contains only the barest outline of such a project, one thing should be absolutely clear, viz. Kant’s conception of the transition project was not static, but constantly expanded over time to match his philosophical ambitions. Whereas he begins by simply trying to explain the specific varieties of matter, he soon comes to believe that his explanatory principle (the dynamic ether) must also serve as a transcendental material condition of experience. This move from natural philosophy back to transcendental philosophy also leads Kant to reexamine the role of the subject in constituting her experience. Although his theory of Selbstsetzung is initially limited to the theoretical domain, he soon expands it to include the practical. This finally leads him to see the theoretically and practically self-positing subject as generating both the physical as well as the moral worlds. In the final analysis, the physical world governed by natural laws and the moral world governed by God’s practical laws are united and made possible only through the subject and her spontaneous free-activity (PCK, ¶ 0.3).

Ad 2. Once Kant recognises that the transition provides conditions for the possibility of experience, one can see how failing to effect this transition would make him think that there was a gap in the Critical philosophy since the Critique of Pure Reason was itself supposed to provide these conditions. It is important to note that this gap is deeper than a failure to complete the ‘doctrinal task’ he sets for himself in the Preface of the Critique of the Power of Judgement vis-à-vis a metaphysics of nature. As I say in my response to van den Berg, Kant’s desire to apply the Critical philosophy to empirical physics does not constitute a gap in the Critical philosophy itself. For the same reason, the problem is deeper than any failure in the General Remark to the Dynamics of the Foundations which likewise aims to apply the Critical philosophy to topics in empirical physics but does not itself meet the standards of a priori construction. As I have argued, such a gap would even have to be deeper than a failure in the main part of the Dynamics of the Foundations given what Kant says in Farrago 1–4 and his distinction between the “transcendental part” and the “special part” of his metaphysics of nature. As I argue in the book and in my response to van den Berg, the gap must lie in the “transcendental part” of Kant’s metaphysics of nature, i.e. the Transcendental Analytic of the Critique of Pure Reason.

Although both Edwards and I might agree the ether is the “highest principle” (OP, AA 21:600) of the transition, I believe that his discussion of the ether concept is too facile and requires us to accept that Kant did not fundamentally change his mind about the ether over the years. To make this claim, he ties Kant’s pre-Critical reflections on the ether directly to his post-Critical comments in the Opus postumum. Although I note this connection as well (PCK, p. 87n7), Edwards’s account demands we ignore the very dismissive things Kant has to say about the ether in the Critical period (see PCK, Chapter Two) which violates my first principle of interpretation. In the Critique of Pure Reason, Kant describes the ether as “a figment of the brain” and “entirely groundless” (A222–3/B269–70). In the Critique of the Power of Judgement, he characterises it as a “matter of opinion” (KU, AA 5:467). Although the ether plays an important role in the Metaphysical Foundations, it is only regulative, allowing one to think of an alternative to atomism’s empty spaces (MAN, AA 4:535) or of how bodies might cohere (MAN, AA 4:564). In the Foundations, the ether is just a hypothesis for the explanation of certain phenomena, a view that Kant explicitly rejects later in Übergang 11 of OP:

The caloric is real and not merely a feigned material for the explanation of certain phenomena, rather, an a priori given material, analytically provable, by the principle of identity, from a universal principle of experience. (OP 21:572; trans. mine).

Not only is the concept of the ether a priori, but that this concept refers to something actual can be proven a priori “not by experience but rather a priori for experience” (OP, AA 21:572; trans. mine).

If one thinks that (1) the transition and the gap are two sides of the same coin, (2) the Ether Deduction is the key to Kant’s transition project, and (3) the gap itself is in the Transcendental Analytic, then one must search for a gap in the Transcendental Analytic that a successful Ether Deduction might fill. In the version of the Ether Deduction from Übergang 11 (which I reconstruct and evaluate in Chapter 3 of PCK), Kant argues that the existence of a plenum of attractive and repulsive forces is necessary to preclude the experience of empty space and so safeguard the unity of experience (OP, AA 21:572–4). At what point in the Transcendental Analytic does Kant talk about something omnipresent as being necessary to preclude the experience of empty space and safeguard the unity of experience? Edwards himself provides the answer, viz. in the Third Analogy of Experience which he connects to Kant’s conception of the ether in OP (Edwards 2000:147–66). I go a step further than Edwards, however, in claiming that this has to be the root of the gap problem itself. Again, I think it is hard to escape this conclusion if one accepts (1)–(3) above since the only place in the Transcendental Analytic where Kant relies on something functionally identical to the ether is in the Analogies of Experience. As Edwards notes, I point to an equivocation in the way Kant deploys the category of substance in the Analogies. In some cases, Kant takes it to apply to ‘Substance’ (omnipresent and sempiternal). In other cases, he takes it to apply to ‘substances’ (spatially discrete and relatively enduring). Since these are different and mutually irreducible conceptions of substance, Kant faces a dilemma:

If the category of substance applies to Substance, then although this would ensure that experience takes place in a common spatiotemporal framework, one could not individuate substances and perceive their alterations. If the category of substance applies to substances, however, then although one could individuate these substances and perceive their alterations, the category would not pick out a common spatiotemporal framework for one’s experience of substances. In neither case would there be a unified spatiotemporal experience of substances (PCK, p. 36).

Edwards claims that he recognises this tension in his book from 2000, but took it “to be simply too obvious to belabor at any given point in the book’s overall argument”. Although Edwards did not provide a citation (in the version of his comments I was provided) to where he recognises this tension, based on what he does say in his comments, one must look to his discussion of the relationship between the First and Third Analogies (Edwards 2000:28–30). The tension he notes, however, is predicated on granting “the isolation of substances by virtue of empty space” (Edwards 2000:28). He resolves this tension by rejecting empty space and elevating the Third Analogy to pride of place within the Analogies as an integrated set.

Ad 3. The problem I pose, however, arises because Kant requires both something omnipresent that precludes the experience of empty space as well as a causal community of individual substances.  Ultimately, what Kant requires is another a priori concept of substance distinct from the schematised category of substance, which I argue, has proper application only to substances (PCK, pp. 46–50, 52). Thankfully, when Kant discusses the gap in Farrago 1, he also makes reference to the a priori concept of the ether as being vital for bridging this gap (OP, AA 21:625). This a priori concept is articulated in the Elementarsystem section of the Opus postumum (1798) which I shall discuss at greater length when responding to the final critic. As a pure concept, it is “one on which, as a priori condition, experience in general (its form) rests” (A220/B267). Although it might seem strange to talk about a pure concept that is not a category, Kant leaves room for such concepts in the Critical period (A224/B271). Kant also distinguishes, in the Farrago section, between the a priori concept of the ether and the ether itself (OP, AA 21:640). In a particularly cryptic passage from Convolut 10 (1800), Kant distinguishes between the a priori concept of the ether (“one system of forces”) and the role that the Principles of Pure Understanding (including the Analogies and so the schematised category of substance) play in his transition project:

Transition to the concept: (1) Axioms of Intuition. (2) From the intuition to perception, perception to experience Analogies. (3) subjective—(4)Transition to the unity of experience in one system of forces objective. (OP, AA 22:289; trans. mine)

Unlike in the Critique of Pure Reason, where the Principles are objectively valid on their own, in Convolut 10 Kant sees the Principles as effecting a transition from subjectivity to objectivity. Objectivity itself, however, is achieved only when the a priori concept of the ether has been applied through the Principles resulting in the unity of experience. This reveals the formal role that the concept of the ether has as the a priori concept for transition as well as how it is distinct from the category of substance as it is deployed in the Analogies (PCK, p. 135). The material role, by contrast, is revealed through the Ether Deduction which, in key respects, mirrors Kant’s argument in the Third Analogy (PCK, p. 95).

Unlike the Analogies, in the Opus postumum Kant clearly discriminates between two different and mutually irreducible concepts of substance. On the one hand, there is the a priori concept of Substance or the ether (where the latter is simply a post-Critical development of the former), and on the other, the category of substance which in its role as a Principle (First Analogy) has direct application to ordinary empirical objects or substances and makes possible the indirect application of the a priori concept of Substance or the ether to the dynamic force plenum in conjunction with the other Principles. Put in terms of the dilemma, the category of substance (qua Principle in the First Analogy) applies to substances insofar as it generates them (in conjunction with the other Principles). This makes possible the application of the a priori concept of Substance (ether) which generates a unified spatiotemporal experience of substances. In other words, applying the a priori concept of Substance or the ether unifies substances within the spatiotemporal framework that the dynamic force plenum underpins. With these two a priori concepts in hand, Kant is able to overcome the dilemma that faces his theory of substance in the Analogies and so fill the gap in his Critical philosophy (PCK, pp. 144–9).

All of this would be for naught if, as Edwards suggests, my dilemma can easily be overcome by appeal to the single schematised category of substance, which could be applied both to substances and Substance “as long as it is employed in accordance with the condition supplied by its transcendental time-determination (i.e., ‘the persistence of the real in time’ [A144/B183])”. He claims that this possibility is not “raised in the course of [my] book’s argument” and that even if I did he doubts that my book “contains the resources needed” for addressing this possibility. Since Edwards must have missed it, I can only suggest that he reread the first chapter of PCK, where I argue that the schematised category of substance is best understood as having application only to substances (PCK, pp. 48–52).

First, one must recognise that Kant uses ‘persistence’ (Beharrlichkeit) equivocally in the Analogies. Although both Substance and substances persist, they persist in very different ways (sempiternal vs. relatively enduring) and more than one a priori concept of substance (conception of persistence) is required to disambiguate these different and mutually irreducible uses of ‘persistence’.

Second, there seems to be good reason for believing that only relatively enduring objects appear in empirical intuition. Empirical intuitions are both singular and immediate (A320/B377). Particular empirical intuitions surely do not all directly or immediately refer to the same Substance. Presumably, there is a sense in which the object of one empirical intuition does not refer to the object of another.

Third, the nature of Substance (omnipresent) seems to preclude it from being perceived in empirical intuition insofar as (objective) perception requires locomotion (MAN, AA 4:477).

Just as I began with a point of agreement between Edwards and myself, I would like to end by noting that I also agree with his closing remark that “the concept of substantial force that the dynamical theory requires cannot be the concept of the mere relation of substance to its accidental determinations”. Although this requires us to accept that Kant reassessed his view of Spinoza, as Edwards himself has aptly noted elsewhere (Edwards 2000:186–90), Kant does precisely this in the latter fascicles of the Opus postumum. Edwards’s closing remark also makes perspicuous one of the most interesting aspects of Kant’s mature view, viz. that what exists in outer sense is not fundamentally compositional stuff but rather dynamic force. As I have argued, this led Kant to reassess his theory of substance and to distinguish between two distinct though related levels: (1) dynamically constituted Substance to which the post-Critical concept of the ether refers and (2) mechanically related substances to which the Critical-era category of substance/accident applies. I discuss this relationship at much greater length in the book (¶¶ 1.3, 2.2, 5.5), which I would invite readers to examine for themselves.     

Response to Kenneth Westphal

Westphal does not challenge the interpretive principles of my book, but rather quotes them at length before mentioning them twice more: (i) in the beginning of his commentary (¶ 2), to assert that “Hall’s effort is neither coherent nor fruitful” and (ii) at the end, to assert that “Hall neither fulfills his four conditions for a good interpretation (above, ¶ 2), nor does he notice his falling short of his stated goals” (¶ 18). Given that there is no mention of these principles in what intervenes, one can only assume that it is self-evident that my book fails to live up to them. Since Westphal does not challenge the principles themselves and considers himself the authority on scholarly standards (¶ 19), one might expect his commentary to live up to the principles for which I have fallen so short. Below, I examine his commentary to see if this is in fact the case.

Westphal traces the root of my failure to the first page of PCK where I quote the Preface to the Critique of the Power of Judgement (KU, AA 5:170). As mentioned in my earlier responses, Kant claims there that his Critical project is complete and that he will hurry to the doctrinal task of “presenting his metaphysics of nature and of morals”. I suggest that Kant may have well completed this latter task with the publication of his Metaphysics of Morals (MS) in 1797, but that he did not publish a corresponding Metaphysics of Nature. Although this way of reading the passage is nothing new (Förster 2000:54), Westphal views it as not only demonstrably false (i.e. that Kant completed both works), but also the foundation for my interpretation of the gap problematic and the transition project. Westphal claims that the Critique of Practical Reason + MS = the metaphysics of morals while KrV + MAN = the metaphysics of nature. A transition project, in both cases, would consist of the application of these complete metaphysical systems to “actual human rights and obligations” (Westphal, ¶ 3) in the case of a metaphysics of morals and (presumably) empirical physics in the case of the metaphysics of nature.

Although it is neither quoted nor cited by Westphal, Kant does say in the Preface to the Metaphysics of Morals that the Metaphysical Foundations of Natural Science is its “counterpart” (MS, AA 6:205). Although this may suggest that Westphal is right, is his view consistent with Kant’s other texts (showing that his interpretation does indeed meet my first principle)? As I note in PCK (p. 26n2), if what Kant means by “counterpart” is that the Metaphysical Foundations of Natural Science completes Kant’s metaphysics of nature in the same way that the Metaphysics of Morals completes Kant’s metaphysics of morals (as Westphal claims), then Kant would have already completed, in 1786, the task he set for himself (i.e. laying out a metaphysics of nature) in 1790. Kant also makes clear in a 1785 letter to Christian Schütz, that the Metaphysical Foundations of Natural Science only provides “concrete examples” that will help to make his yet to be completed metaphysics of nature “comprehensible” (Br, AA 10:406).

Likwise, Kant reiterates in the B-edition Preface to the Critique of Pure Reason (1787) that “I must proceed frugally with my time if I am to carry out my plan of providing the metaphysics both of nature and of morals” (Bxliii), i.e. Kant does not view himself as having completed his metaphysics of nature in 1786. Westphal does not mention these passages much less try to make sense of them. Even when he does mention a passage that contradicts his view, he says nothing of it. For example, Westphal includes the Metaphysics of Morals in the “official Critical corpus” (¶ 2) while including the nested quotation from the Critique of the Power of Judgement immediately thereafter (¶ 3), where Kant makes clear that the Critical philosophy is complete and that the metaphysics of morals is not a part of it. Not only does Westphal’s view violate my first interpretative principle (textual consistency), but also my second interpretative principle (insofar as Kant is made to be inconsistent with himself).

Secondly, and far more importantly from the perspective of my interpretative principles, the relationship between the metaphysics of morals and the metaphysics of nature is irrelevant to understanding my view of the transition and the gap. I only note the difference in order to start discussing the components of Kant’s metaphysics of nature. Even if, pace Westphal (but contra the Critique of the Power of Judgement and other texts), the metaphysics of nature is complete in 1786 (with the publication of the Metaphysical Foundations of Natural Science), Kant came to recognise in 1798 letters to Garve and Kiesewetter that there was a gap in the Critical philosophy (Br, AA 12:257–8). As I have argued above in response to the other critics, Farrago 1 of the Opus postumum makes it clear that (pace Tuschling) this gap lies in the “transcendental part” of Kant’s metaphysics of nature (OP, AA 21:626). Although Kant’s original plan for a transition was separate from the gap problematic, Kant redescribed his transition project so as to fill the gap that he identifies in 1798. Again, as I note above in response to others, Kant’s conception of the “metaphysical foundations of natural science” changes with the modifications he makes to the transcendental part of the metaphysics of nature, and his views of “physics” and “transition” broaden over time so that he can fill the gap that he discovers in the Critical philosophy. Strangely, given his apparent agreement with Edwards’s view on the timeline (¶ 1), Westphal nonetheless grants that “these alleged issues [gap and transition] appear to have begun separately, though ultimately Kant’s Opus postumum proposes a single solution consisting in his late ‘Transition’ project, Übergang 1–14″ (¶ 3). This is far closer to my view than it is to Edwards’s own. Not only does Westphal’s commentary betray a profound ignorance of the Opus postumum (he does not cite it a single time in support of any claim he makes), it also betrays an equally deep misunderstanding of my book. This again violates my first principle of interpretation (with respect to both the Opus postumum and my book).

Westphal’s next main concern is that whereas Kant is a fallibilist about empirical knowledge I “presume infallibility” (¶ 8). While I argue that Kant believed that there was no “in principle discontinuity between the systematic unity of nature and the subject’s cognition of this systematic unity” (PCK, p. 141), I also say that “I do not want to claim that the transcendental conditions of experience are sufficient to establish the details of experience, though they are sufficient to establish the general conditions under which experience is unified” (PCK, pp. 97–8). Westphal quotes the former while not mentioning the latter. While Kant believes that he can establish that our empirical judgements are not systematically false, he still leaves room for misjudging in individual empirical cases. My concern with a “sufficient mark of empirical truth” applies at the global, not the local level. Since Westphal ignores what I do say, he is forced to impute to me implausible things that I do not say. This violates both my first as well as my third principles of interpretation.

Westphal lodges other objections based on the claims that (1) “Kant’s æther or caloric consists (officially) only in attractive force” (¶ 11) and that (2) “if Kant’s æther were SUBSTANCE or a substance it would have mass” (¶ 12). By “official”, Westphal is presumably referring (though he does not cite or quote it) to Kant’s published view in the Metaphysical Foundations of Natural Science (MAN, AA 4:564). Westphal does not mention, however, Kant’s very different pre-Critical accounts of the ether (discussed by Edwards in his commentary) or Kant’s other Critical accounts (which I discuss in my response to Edwards above), all of which are likewise published. More importantly, by focusing on what is published, Westphal simply begs the question against any study of the Opus postumum (or of the Reflexionen, Correspondence, etc.). Although this may explain, it does not excuse his ignorance of the Opus postumum. At the beginning of Chapter 2 of PCK, I quote a passage from Übergang 2 of the Opus postumum that does a good job of summarising Kant’s mature view of the ether:

There exists a matter, distributed in the whole universe as a continuum, uniformly penetrating all bodies, and filling [all spaces] (thus not subject to displacement). Be it called ether, or caloric, or whatever, it is no hypothetical material (for the purpose of explaining certain phenomena, and more or less obviously conjuring up causes for given effects); rather, it can be recognized, and postulated a priori, as an element necessarily belonging to the transition from the metaphysical foundations of natural science to physics. […]. It is to be acknowledged as a primordially moving material—not hypothetically invented, but one whose forces give it reality and which underlies all motion of matter; a continuum which, taken in its own right, forms a whole of moving forces, whose existence is known a priori. (OP, AA 21:218, 223–4)

Regardless of the name that is used (caloric, ether, etc.), it is a “universally distributed” and “sempiternal” (OP, AA 21:584) plenum of dynamic (attractive and repulsive) forces. Its dynamic activity is the ultimate source of perceptual affection and the material ground for physical bodies that subjects experience in space and time (OP, AA 22:194). Mechanical forces (locomotion in space) depend upon these (internally moving) dynamic forces (OP, AA 22:239). Since it is omnipresent and sempiternal, it precludes the experience of empty space and time (OP, AA 21:219–20). One could metaphysically summarise many of these properties by saying that the ether is a compositionally plastic, intrinsically structural, substrate of dynamic forces. Contra Westphal, the ether is no longer a “hypothetical material in order to explain certain phenomena”, e.g. cohesion through universal attraction as it is in the Metaphysical Foundations. It is likewise false to state that Substance or the ether has mass. Whenever Kant is talking about mass, he is operating at the level of substances and not Substance. In the Elementarsystem section of the Opus postumum (1798), Kant gives a purely negative characterisation of the ether or Substance in terms of the properties that physical bodies (or what I have called ‘substances’) might possess:

Imponderable—incoercible—incohesible—inexhaustible. That all of these moving forces stand under the system of categories, and that one universal [matter] primitively underlies them all. (OP, AA 21:183)

Kant argues that the ether cannot be weighed, forced, cohered or exhausted. Even so, the ether is what makes the weighability, forcing, cohesion and exhaustion of physical bodies (either fluid or solid) possible (PCK, p. 81). Although Westphal would likely consider all of this to be mere “doxography” (¶ 7), my first principle of interpretation requires that we consider what a philosopher actually says before we go on to criticise or defend that philosopher.

Although Westphal has only a passing interest in my book and shows no interest in the Opus postumum (notwithstanding the topic of my book!), he carves out a significant amount of time to talk about his own work. He complains that I ignore (1) his arguments against transcendental idealism (¶ 17), (2) his semantics of singular cognitive judgement (¶¶ 9 and 14), and (3) his counterexample to the First Analogy’s conservation principle (¶ 12). He also bridles at my characterisation of his view as (4) claiming that the three Analogies of Experience could all be explained by Substance (¶ 16) and (5) subscribing to transcendental realism (¶ 17). I shall respond to each complaint in turn.

Ad 1. Westphal claims that “although transcendental idealism is coherent, none of Kant’s arguments for it are valid, and they are shown to be invalid by Kant’s own central analyses and proofs in the Transcendental Analytic” (¶ 17). The central analysis upon which Westphal relies is Kant’s discussion of transcendental affinity in the A-edition Transcendental Deduction. In brief, Westphal argues that the transcendental affinity of the sensory manifold is a non-subjective material condition for experience and since transcendental idealism allows for only subjective formal conditions, this objective material condition undermines transcendental idealism and establishes what Westphal calls “realism sans phrase”. Rejecting this material condition, by contrast, would entail unrestricted subjective idealism (Westphal 2004, Chapter Three). Although others have questioned whether transcendental affinity is a material condition (Schulting 2009:384–5), have denied that rejecting this material condition would entail unrestricted subjective idealism (Dicker 2008:742), or have argued that transcendental idealism need not account for the origin of transcendental affinity (Kannisto 2010:240–1), I attack Westphal’s position at an even more fundamental level. I argue that even if one assumes that there is an objective material condition for experience, that this condition could still be consistent with transcendental idealism.

In ¶ 3.4 of PCK, I argue that the ether (a non-subjective material condition for experience) is “materially necessary”, according to the Third Postulate, since its “connection with the actual is determined in accordance with the general conditions of experience” (A218/B266). In the Übergang section, Kant emphasises the material necessity of the ether, calling it a “necessary phenomenon” (OP, AA 21:584). Westphal’s realism sans phrase describes a world of “spatiotemporal, causally interactive substances” that have these properties “regardless of whether we exist or experience them” (Westphal 2004:85). Although Westphal thinks that we do experience these objects insofar as they possess these properties and their affinity accounts for the regularity of our experience, a realism sans phrase requires that these objects are actual regardless of their connection “with the material conditions of experience” (A218/B266).

Whereas the subjective formal conditions of experience (space, time, categories and apperception) are transcendentally necessary insofar as they are required for the possibility of experience for creatures like us, the ether is also materially necessary in addition to being transcendentally necessary since its actuality is required as a condition of possible experience. As Kant says in Übergang 8, “the all-penetrating caloric is the first condition of the possibility of all outer experience” (OP, AA 21:551). Updating Kant’s conception of transcendental material necessity, the necessity of the ether can be understood in the following way: in all and only possible worlds where there is a unity of experience and creatures cognitively similar enough to us, the ether exists as a non-subjective material condition of experience. In contrast, although Westphal’s realism sans phrase can accept that spatiotemporally, causally interactive substances exist in all possible worlds where there is a unity of experience and creatures cognitively similar enough to us, it cannot claim that these substances exist in only these worlds since he insists that these substances exist regardless of whether we exist or experience them.

The conclusion of the Ether Deduction establishes only the transcendental material necessity of the ether. This is modally weaker than Westphal’s realism sans phrase. Since the ether is actual only relative to the conditions of possible experience, it is transcendentally ideal. Since the ether is actual, according to these conditions, it is likewise empirically real. Consequently, even if there is a non-subjective material condition for experience, this does not undermine transcendental idealism. Notice that I do not appeal to transcendental idealism in order to rebut Westphal’s realism sans phrase (contra what Westphal suggests in ¶ 17). Rather, I argue that a non-subjective material condition of experience does not entail the kind of realism he thinks that it does (for the record, I do the same in Hall 2009). Here, it is important to note how Westphal’s interpretation requires us to accept that Kant fundamentally misunderstood his own philosophical project (i.e. that his arguments in the Transcendental Analytic actually undermine transcendental idealism). This violates my fourth principle of interpretation. Holding all else equal (i.e. that the other interpretative principles are met) an interpretation that does not impute this kind of misunderstanding to Kant (e.g. my own) should be preferred to one that does (e.g. Westphal’s).

Admittedly, Westphal claims that the ether is insufficient for transcendental affinity since “numerical unity alone cannot do the job” of insuring the world “exhibits a humanly identifiable variety and regularity of identifiable individuals exhibiting characteristics of identifiable kinds” (¶ 13). As I have already argued above, the ether (as a dynamic force plenum) possesses other characteristics relevant to establishing this variety and regularity (e.g. by serving as the material ground for substances and the dynamical ground for their mechanical relations). Also, I never claim that the ether alone can do the job that Westphal requires. The final chapter of PCK is dedicated to examining the Selbstsetzungslehre in Convolut 7 of the Opus postumum (1800) which argues, inter alia, that the world Westphal describes (causally related spatiotemporal objects and embodied subjects) emerges from the material activity of the ether in conjunction with the mental activity of the subject. Whereas Westphal believes that these objects are mind-independent, one of the main themes of this chapter is that objects and subjects are interdependent and that appearances are intrinsic relations between them. Contra Westphal, the choice between “realism sans phrase” and “unmitigated subjective idealism” is a false dichotomy. I shall not go into this in greater detail since Westphal himself passes over this entire discussion in silence. I would rather encourage Westphal and the reader to examine it themselves.

Ad 2. Westphal complains that I ignore his semantics of singular cognitive judgement when it comes to the application of the a priori concept of the ether or Substance. Although I recognise that applying this concept through cognitive judgement is a problem that Kant has to solve, on the same page that Westphal cites but mischaracterises (PCK, p. 24), I begin to sketch how Kant thinks this is done. As I note above in response to Edwards, in Convoluts 10-11 of the Opus postumum, Kant argues that the a priori concept of the ether is applied through the Principles resulting in the unity of experience. In addition, Kant proves that this concept is instantiated in the Ether Deduction. Although Westphal baldly asserts that “this proof must be much more exacting and cogent than any such argument sketched by Hall”, he says nothing else of the argument itself as well as its formal reconstruction (see PCK, ¶ 3.2).

Ad 3. Westphal claims that I ignore his counterexample to the First Analogy’s conservation principle. The B-edition principle of the First Analogy claims that

[i]n all change of appearances substance persists, and its quantum is neither increased nor diminished in nature. (B224)

Kant’s argument in the First Analogy is based on the idea that the absolute arising/perishing of substance (i.e., arising from an empty time or perishing into an empty time) would violate the unity of temporal experience and generate disconnected temporal continuums. I argue that the sempiternality of Substance precludes this possibility (PCK, ¶ 1.1). Westphal’s purported counterexample is a ‘recalcitrant billiard ball’ (Westphal 2004, ¶ 56) whose strange behavior cannot be explained in terms of external forces. This is no counterexample to the First Analogy, however, since it neither arises from nor perishes into an empty time. What if his ball were to just pop into or out of existence? This is likewise not a problem if we distinguish between Substance and substances. If the former is sempiternal, then the latter would neither arise from nor perish into an empty time.

Ad 4. When I am not ignoring his work, Westphal claims I misrepresent it (here we share similar views of one another). For example, I say he holds that the three Analogies of Experience can all be explained by Substance. He rejects this characterization, holding instead that he does not appeal to my concept of Substance in any sense. By way of justification, he says:

One single, sufficiently large, perceptible physical (material) substance […] instantiates and illustrates equally well the principles of causal judgment Kant identifies and justifies in the first two Analogies of Experience. A plurality of distinct physical substance is required, however, by the principle of causal judgment Kant specifies and defends in the Third Analogy (¶ 16).

Let us compare this with what he says in the work I referred to in PCK:

On a (roughly) Spinozistic physical monism, there is only one physical object, though it is quite complex and comprises a huge number of distinct parts, aspects, or “modes”. These aspects or modes of substance are causally related […]. In this way one could account for (or at least accommodate) any of our judgments about physical phenomena Kant sought to account for, while nevertheless denying that causal relations hold between distinct substances. While such Spinozism was widely abhorred in Kant’s day, nothing that Kant argues in the first Critique rules it out [citation to Edwards’s account of the ‘physically monistic æther’ in the Opus postumum] […]. The plurality of substances is a mere assumption of Kant’s analysis and is not entailed by the principles of the Analogies. (Westphal 2004:161)

I think one may be forgiven if one concluded from the latter passage that Westphal thought something like Kant’s ether or what I call ‘Substance’ (sempiternal and omnipresent) could account for all three Analogies. In the interest of charity, however, let’s say that Westphal has abandoned this position. What of it? Although he reduces Kant’s argument against empty space in the Third Analogy to a “mere hint” in his comments (¶ 16), in his earlier book it was one of two “key arguments” for realism sans phrase in the Transcendental Analytic (Westphal 2014:121). Since I have shown Westphal’s first argument above (from transcendental affinity) to be invalid, given Westphal’s new position on the Third Analogy, what is left is a realism sans ratio.

As a minor though related point, Westphal says that I simply assume that “Kant’s three principles of cognitive judgement form an integrated set” (¶ 6). This is false. I talk about not only how the three principles stand or fall together (PCK, p. 66n45) but also how my conception of Substance integrates all three (PCK, pp. 39–42). Like so many other arguments and texts already mentioned, Westphal again passes over these in silence.

Ad 5. Finally, although Westphal claims that I misunderstand his ‘realism sans phrase‘ as a form of ‘transcendental realism’, if realism sans phrase “regards space and time as something given in themselves […] [and] represents outer appearances […] as things in themselves, which would exist independently of us and our sensibility” (A369), then is it not a form of transcendental realism? If not, then I must admit that I am too dull (and so is Kannisto 2010:229n9) to discern his meaning. At this point I suspect, however, that like Oscar Wilde before him, Westphal may “live in terror of not being misunderstood” (Wilde 2007:136).

Dennis Schulting remarks that “in his boldness [Westphal] often blatantly misrepresents the textual evidence so as to find support in Kant” (Schulting 2009:385). One can see this same tendency toward blatant misrepresentation in Westphal’s commentary on PCK. Depending on how the misrepresentation is carried out (e.g. through ignoring key texts) and the ends toward which it is applied (e.g. to generate a contradiction within a view, to show a key problem is not solved, or provide a deflationary interpretation), Westphal can be seen as routinely violating all four of my interpretative principles. Far from establishing that my work fails to meet the standards it sets for itself, one can rather establish that Westphal fails to meet the standards of scholarship that he claims to defend. A moment’s reflection is sufficient to show why this could not have been otherwise. My book accepts much of what Westphal says about Kant’s arguments against empty space and what transcendental affinity requires. Even while granting Westphal’s premises, I show that his central conclusion (realism sans phrase) does not follow. This is a very powerful refutation of Westphal’s view. The main goal of Westphal’s commentary is to show that there is nothing to recommend my book. This requires systematic misrepresentation. Approaching my book in a scholarly fashion would make this goal impossible to achieve, though it would have been far more fruitful insofar as he would have had to countenance the very serious problems his own view faces.

Received: 20 October 2016.


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Dicker, G. (2008), Review of Kenneth Westphal: Kant’s Transcendental Proof of RealismPhilosophy and Phenomenological Research 76(3): 740–5.

Edwards, J. (2000), Substance, Force, and the Possibility of Knowledge (Los Angeles: University of California Press).

Förster, E. (2000), Kant’s Final Synthesis: An Essay on the Opus postumum (Cambridge, MA: Harvard University Press).

Friedman, M. (1992), Kant and the Exact Sciences (Cambridge, MA: Harvard University Press).

Hall, B. (2009), ‘Effecting a Transition: How to Fill the Gap in Kant’s System of Critical Philosophy’, Kant-Studien 100(2): 187–211.

Hoppe, H. (1969), Kants Theorie der Physik Eine Untersuchung über das Opus postumum von Kant (Frankfurt a.M: Klostermann)

Kannisto, T. (2010), ‘Three Problems in Westphal’s Transcendental Proof of Realism’, Kant-Studien 101(2): 227–46.

Schulting, D. (2009), Review of Kenneth Westphal: Kant’s Transcendental Proof of RealismKant-Studien 100(3): 382–5.

Tuschling, B. (1971), Metaphysische und Transzendentale Dynamik in Kants Opus postumum (Berlin: de Gruyter).

Westphal, K. (2004), Kant’s Transcendental Proof of Realism (Cambridge: Cambridge University Press).

Wilde, O. (2007), The Complete Works of Oscar Wilde, ed. J. Guy (Oxford: Oxford University Press).

© Bryan Hall, 2016.

Bryan Hall is Professor of Philosophy and Associate Dean for Undergraduate Studies at St. John’s University, New York. Together with two of his undergraduate students, he co-authored The Arguments of Kant’s Critique of Pure Reason (Lexington Books, 2010). He has also published several articles on Kant’s theoretical philosophy that have appeared in journals such as the British Journal for the History of Philosophy, Kantian Review and Kant-Studien.