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


By Jeffrey Edwards 

Bryan Hall’s approach to Kant’s late philosophy is consistent with my own in one important respect. He insists that the Opus postumum’s æther deduction provides the main platform for understanding the surprising directions that Kant’s thinking takes during the final decades of his philosophical career. While recognising that we share common ground with regard to this pivotal supposition, however, my comments will concentrate on a number of areas in which the lines of our interpretative arguments diverge. I shall limit my discussion of these areas of divergence to Hall’s understanding of the gap in Kant’s system of Critical philosophy, and thus to Hall’s account of the tensions and inconsistencies in Kant’s theory of substance.

1. Hall on the Gap in Kant’s Critical Philosophy

The following passages from The Post-Critical Kant allow us to put together a reasonably clear picture of Hall’s account of the gap in Kant’s system:

[A] As I will argue, the gap in Kant’s Critical philosophy lies in the transcendental part of the metaphysics of nature that he presents in the Transcendental Analytic of CPR. In particular, I will claim that the gap stems from problems that face the Analogies in CPR and that Kant would face these problems regardless of whether MFNS is successful. (p. 23)

[B] […] Kant faces a dilemma when applying the category (or a priori concept) of substance. Briefly stated, 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 substance 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 experiences of substances. In neither case would there be a unified spatiotemporal experience of substances. (p. 36)

[C] [W]hen Kant talks about substance he is not always talking about the same thing. There is the relative persistence of individual substances as well as the sempiternal persistence of omnipresent Substance […]. [T]his creates a dilemma for Kant’s theory of substance that he is unable to resolve within  the contexts of CPR. Consequently, this dilemma opens up a gap in the transcendental part of his metaphysics of nature […]. I will argue that Kant can overcome the above dilemma that faces the Analogies [of Experience] by deducing a priori a concept of Substance different from the category (a priori concept) of substance that has its application only to substances that appear in empirical intuition. (p. 50)

[D] Insofar as the application of the category of substance must be limited to substances, Kant requires a new a priori concept of Substance different from the category of substance. In my view, this constitutes a gap in Kant’s Critical philosophy that he is unable to deal with given the tools available to him in CPR. This is a gap in the transcendental part of the metaphysics of nature since it lies at the heart of his project in the Transcendental Analytic, viz. the Analogies of Experience. (p. 51)

[E] [The æther deduction] thus serves a two-part function. (1) It exposes a gap in the Critical philosophy by showing that the cognitive formal transcendental conditions of CPR are not jointly sufficient to guarantee the unity of experience. This is a gap in the transcendental part of the metaphysics of nature and is precipitated by the failure of Kant’s argument for Substance in the Analogies. (2) It seems to fill this gap by deriving a concept of the ether a priori while also proving the existence of the ether. Kant’s post-Critical concept of the ether is consistence with his Critical conception of Substance and the ether itself is a transcendental material condition for the unity of experience. (p. 106)

[F] [O]ne should look for the gap in the Transcendental Analytic of CPR […]. I argued that this gap can be located in the Analogies of Experience in CPR, where Kant faces a dilemma given the fact that he has only one concept of substance (the a priori category) which is insufficient to disambiguate between the two different and mututally irreducible conceptions of substance he makes use of in the Analogies (Substance and substances). (p. 207)

[G] Although Kant cannot overcome this dilemma in CPR, a solution can be found in the transition project of OP. This solution is post-Critical insofar as it modifies the Critical philosophy in certain fundamental ways […] In OP, Kant not only develops his conception of Substance or what he now calls the “ether” […], but also provides an a priori deduction for its actuality in the Übergang section which simultaneously generates an a priori concept of Substance different from the a priori category of substance […]. Having these two concepts in hand allows Kant to avoid the dilemma that he faces in the Analogies of Experience and so fill the gap in the transcendental part of his metaphysics of nature. Kant fills this gap in Convoluts 10–11. (p. 208)

[H] Filling the gap is intimately tied to his transition project in Convoluts 10–11. The twin purposes of the transition are to establish the system of physics in its two aspects, as the (1) unity of experience (absolute unity of consciousness) which corresponds to the (2) unity of matter (ether). Just as there is only one experience, so too is there only one matter that ultimately produces the perceptions that the subject unities through the a priori concept of this matter (i.e., the a priori concept of ether or Substance) into this one experience. / The ether is the ultimate material condition for the objects of experience and the concept of the ether is the ultimate conceptual condition for these objects. (p. 208)

In view of the representative passages just quoted, I take it that Hall’s account of the systematic gap in Kant’s Critical philosophy revolves around ten key assumptions:

  1. Such a gap has nothing directly to do with various problems in the special metaphysical natural science furnished by the Metaphysical Foundations of Natural Science of 1786.
  2. Instead, the gap in Kant’s Critical philosophy lies in the transcendental part of his metaphysics of nature.
  3. This gap results from the theory of substance at issue in the First Critique’s Analogies of Experience.
  4. The Analogies of Experience operate with two distinct conceptions (i.e. views) of substance, viz. (i) the conception of substance involved in Kant’s characterisations of particular substances persisting through time and (ii) the conception of substance involved in Kant’s characterisations of substance as something that persists through time as a single omnipresent entity (i.e. ‘Substance’).
  5. These distinct conceptions of substance stem from Kant’s use of two different a priori concepts of substance, viz. (i) the category of substance, which has its proper application to the particular substrata of time-determination that can be identified in empirical intuition and (ii) the concept of ‘Substance’ furnished by Kant’s dynamical idea of physical æther.
  6. The gap located in the transcendental part of Kant’s metaphysics of nature is a function of a dilemma for Kant’s theory of substance that derives from his failure, in the Critique of Pure Reason, to pull apart the two mutually irreducible conceptions of substance which correlate with the distinct a priori concepts of substance just mentioned.
  7. The Opus postumum’s æther deduction exposes the theoretical deficit linked to this dilemma when it attempts to prove the existence of physical æther as a material transcendental condition, thereby showing that the purely formal and subjective conditions of our possible experience of objects of outer sense (i.e. the strictly formal transcendental conditions established in the First Critique’s Transcendental Analytic) do not suffice to ground the unity of objective experience.
  8. The solution to both the dilemma implicit in Kant’s metaphysical theory of substance and the problem of the gap in his system of Critical philosophy lies in a crucial dimension of the Opus postumum’s transition project: This project’s æther deduction generates an a priori concept of Substance unambiguously different from the category of substance employed in the Transcendental Analytic.
  9. Having these two distinct concepts of substance in hand is what allows Kant to fill the gap in his metaphysics of nature.
  10. The completion of this gap-filling task takes place in manuscript materials written after Übergang 1–14. Specifically, it occurs in X/XI Konvolut, where Kant attempts to work out a causal theory of perception that requires the concept of ‘Substance,’ i.e. the a priori concept of substantial persistence that applies to the æther as the ultimate material condition for our possible experience of objects.

There are two very basic questions raised by the claims just listed: Are they consistent with what Kant actually says about the gap in his Critical philosophy? How do they stack up against what Kant in fact argues about the relationship between substance, substances, and physical æther? I shall answer these questions in the order that I have raised them.

2. Metaphysical Foundations, Transition and the Gap

One of the most striking features of Kant’s thinking in the Opus postumum manuscripts composed after 1796 is his concern with a mediating scientific discipline that he characterised as ‘transition’ (Übergang). Kant’s views on the contents and the scope of his transitional science are not definitively settled in the Opus postumum. Thus, because the notion of transition has always presented a moving target ideal for the generation of interpretative controversy, the secondary literature has never arrived at a stable consensus concerning the significance of Kant’s late transition project for his theory of a priori cognition or for his philosophy of nature in general. Nonetheless, there was until fairly recently a broadly shared tenet that, as it seemed, could reliably play an essential role in most any chronologically sensitive account of that project’s place and purpose in Kant’s late philosophy. The standardly accepted tenet was this: Kant intended the Opus postumum’s transition project to fill the gap in his system of Critical philosophy that he specifically mentions in a letter to Christian Garve dated September 21st, 1798. I quote here the lines in this letter where Kant makes clear his concern with this architectonic gap:

Die Aufgabe, mit der ich mich jetzt beschäftige, betrifft den »Übergang von den metaphys. Anf. Gr. d. N. W. zur Physik«. Sie will aufgelöset seyn; weil sonst im System der crit. Philos. eine Lücke seyn würde. Die Ansprüche der Vernunft darauf lassen nicht nach: das Bewustseyn des Vermögens dazu gleichfalls nicht; aber die Befriedigung derselben wird, wenn gleich nicht durch völlige Lähmung der Lebenskraft, doch durch immer sich einstellende Hemmungen derselben bis zur höchsten Ungedult aufgeschoben. (Br, AA 12:257.8–15)

The problem with which I am now occupied concerns the “transition from the metaphysical foundations of natural science to physics”. It needs to be solved since otherwise there will be a gap in the critical philosophy. Reason’s demands for this do not lessen—nor can [my] awareness of the capacity involved diminish; yet the satisfaction of those demands keeps being postponed to the point of utter vexation, if not by the complete paralysis of my vital powers then by their repeatedly occurring inhibition. (trans. mine)

The natural way of reading these lines is to take Kant as saying that the transition project on which he is currently working is supposed to fill the gap in the architecture of his Critical philosophy that is located between the metaphysical foundations of natural science and physics.[1] According to this prima facie compelling reading, then, ‘transition’ and ‘gap’ designate two sides of the same architectonic coin. And this, it seems, should provide the piece of common currency that must retain its value for every plausible interpretation of Kant’s theoretical concerns in the Opus postumum.

The coin in question started to lose its exchange value in the late 1980s,[2] and the devaluation process hit its crisis stage in 2000 with the publication of Eckhard Förster’s book, Kant Final Synthesis (Förster 2000). According to Förster, the assumption that transition and gap originally refer to two aspects of the same theoretical task amounts to a widespread but unwarranted “dogma in Kant scholarship” (Förster 2000:50); and this dogma has to be deflated if we are ever going to get a grip on Kant’s genuine view of the gap in his system of Critical philosophy. Moreover, the proper way to deflate the dogma is to argue—contrary to appearances—that the gap to which Kant refers in his letter to Garve is simply not the same thing as the systematic shortcoming that Kant wants to remedy by working out a viable transition from the metaphysical foundations of natural science to physics.

So what exactly do these considerations on Förster have to do with Hall’s book? The answer to this question is straightforward enough: The centrepiece of Hall’s overall interpretative endeavour, i.e. his particular account of the gap in Kant’s Critical philosophy, builds on his endorsement of the chief result of Förster’s dogma deflating argument. That is, Hall’s understanding of the gap problematic in Kant’s late philosophy assumes that Kant’s original plan for a transition project (i.e. the project pertaining to the relationship between the metaphysical foundations of natural science and physics) can be kept separate from his recognition of a gap in his Critical system as such (p. 21). To be sure, Hall by no means shares Förster’s particular views on the nature and location of that gap. Nonetheless, Förster’s challenge to the historically standard assessment of the relationship between transition and gap is effectively what furnishes the license for Hall’s attempt to locate the latter at the very core of Kant’s theory of our a priori cognition of objects: the Analogies of Experience. In particular, it is Hall’s acceptance of the key elements of Förster’s deflationary argument that enables him to repudiate, or substantially revise, Burkhard Tuschling’s influential views on the origin of the transition project and the nature of the gap in Kant’s system (pp. 19–21). Thus, if we can show that the type of challenge presented by Förster’s argument cannot be upheld, then we can also be confident that the centrepiece of Hall’s interpretative endeavour lacks support in Kant’s philosophy.

My previously published criticism of Förster’s portrayal of the transition/gap relation is not mentioned in Hall’s list of references in The Post-Critical Kant. But it seems appropriate to drag it out of mothball storage in a conference volume and put it to work for my evaluation of Hall’s corresponding portrayal. The following remarks on Förster and Tuschling are an adaptation of the first and second parts of my article, ‘Transition and Gap in Kant’s Opus postumum (Edwards 2008:231–7).

According to Förster, as we have seen, ‘transition’ and ‘gap’ cannot simply be taken as terms designating two facets of the same theoretical undertaking because the transition project did not originate in the particular systematic concerns to which the notion of gap is linked. The transition enterprise, Förster maintains, originated in connection with the Critique of Judgement’s account of reflective judgement and the problem of the systematicity of nature according to nature’s empirical laws. The structural gap in the system of a priori knowledge, however, was tied to Kant’s acknowledgement of the substantive flaws in the dynamical theory of matter that he had presented in the Metaphysical Foundations of Natural Science (1786). Thus, at least in the manuscripts of the Opus postumum composed prior to midyear of 1799, Kant’s response to the problem of the gap in his Critical system must not be understood in terms of the same set of architectonic issues that stem from the transition’s genetic connection with the principle of the formal purposiveness of nature (Förster 2000:50).

Instead, Kant’s response represents the attempt to redefine and ground anew the conditions for the “real applicability and objective validity” (Förster 2000:59) of the concepts and principles of pure understanding in the face of the flawed theory of matter set forth in the Metaphysical Foundations of 1786. It was only at a relatively late date in the compositional history of the Opus postumum manuscripts that Kant tried to forge a firm link between the transition project and his response to the problem of the system gap—first, by linking a general principle for the classification of nature’s moving forces and varieties of matter to the concept of a universally distributed physical æther; second, by attempting to prove a priori the existence of this cosmic æther as a universal material condition of unified experience; and finally, by endeavouring to demonstrate that the transition’s concepts of moving forces and elementary properties of matter are integral elements of the human knowing subject’s self-positing activity (see Förster 2000:75–116).

So much for the general strategy of argument by which Förster seeks to overcome the purportedly dogmatic attitude that long prevailed in scholarly work concerned with the development of Kant’s late philosophy. To make this strategy work, Förster has to establish the transition project’s chronological priority in the course of this development during the 1790s. In particular, establishing this priority is essential to Förster’s refutation of the competing account of the transition project’s emergence and systematic significance that Burkhard Tuschling gives in his influential book on Kant’s metaphysical and transcendental dynamics (Tuschling 1971). According to Tuschling, Kant’s plan for the transition derived from his realisation that the deductive procedure of the 1786 Metaphysical Foundations was irreparably flawed. This realisation, Tuschling argues, led Kant to recognise that the special metaphysical natural science furnished by this work was untenable, especially the part of this science supplied by the 1786 version of the dynamical theory of matter. Moreover, this recognition is what drove Kant to acknowledge the architectonic gap in his Critical philosophy of nature; and Kant understood this gap to be something that could be remedied only by means of a fundamentally reworked dynamical theory of matter constructed on the basis of a substantially revised conception of natural science’s metaphysical foundations.

On Tuschling’s view, then, the transition project is the attempt to fill the architectonic space left vacant by Kant’s recognition that the Metaphysical Foundations of 1786 was deficient, above all on account of its inadequate version of the dynamical theory of matter. Thus, according to Tuschling, the idea of transition presupposes Kant’s realisation that this published work of 1786 did not suffice to ground physics as an empirical science as well as his de facto admission that a new version of his theory of matter was essential to achieving this end.[3] In brief, the origin of the Opus postumum’s transition project cannot be separated from Kant’s concern to provide a coherent dynamical theory of matter; and this theory is exactly what Kant was concerned to provide in his late work on the theory of physical æther.  

The summary conclusion just stated appears to be well supported by the texts available to us. More precisely, it is strongly suggested by the fact that there is no direct textual evidence for Kant’s engagement with the transition project until well after his first explicit acknowledgement that the dynamical theory of the 1786 Metaphysical Foundations was deficient in carrying out one of its key explanatory tasks. In fact, according to Tuschling, the first clear indications of this engagement stem from 1795; and it was not until the Opus postumum manuscript titled Oktaventwurf (OP, AA 21:373.1–412.4), which dates from 1796 or 1797, that Kant explicitly took up the task of providing a transitional science.[4] Thus, in order to establish that the origin of the transition cannot plausibly be traced to Kant’s revision of his dynamical theory of matter, Förster has to show that the broader inventory of historical evidence allows for a chronology of the transition’s genesis which differs radically from Tuschling’s dating procedure. Förster does this by taking account of certain biographical factors relevant to the interpretation of a letter from Johann Gottfried Carl Christian Kiesewetter that contains the first known reference to Kant’s own use of the term ‘transition’ in connection with the Metaphysical Foundations of Natural Science. By reconstructing the background to Kiesewetter’s relations to Kant from the late 1780s until 1795, Förster is able to argue that the Kiesewetter letter to Kant dated June 8, 1795 (Br, AA 12:23.1–24.25) contains at least indirect indications that Kant had discussed a transition project by autumn of 1790, if indeed not beforehand. This in turn puts Förster in a position to link the transition’s source to the Critique of Judgement, and thus to Kant’s considerations on the principle of the formal purposiveness of nature (see Förster 2000:3, 5–6).

The particular reasons that Förster gives for placing the transition project’s origin in 1790 (if not earlier) are, I think, compelling.[5] I therefore accept that Kant in fact expressed the need for such a theoretical undertaking by autumn of 1790 at the latest. But does granting this chronological point suffice to exclude the type of account of Kant’s transition project that Tuschling advocates?[6] In my judgement it cannot suffice for this purpose. Indeed, I think that Förster’s entirely convincing dating procedure is exactly what strengthens the view that transition and gap must be regarded as two sides of the same architectonic coin. To see why, let us briefly consider some important aspects of Kant’s thinking in the oldest parts of the Opus postumum.

The very oldest components of the Opus postumum—the loose leaves gathered in the fourth fascicle (one of which is datable as early as the end of 1786[7])—clearly demonstrate Kant’s great interest in exploring the consequences of assigning a central role to physical æther (or caloric) in the dynamical explanation of natural phenomena.[8]This concern with physical æther, of course, is the most striking characteristic of the dynamical theory of matter that later (see Oktaventwurf of 1796/97) supplies the concepts used to forge the transition from the metaphysics of corporeal nature to empirical physics.[9] Moreover, that very same concern is also a significant feature of the Dynamics of the 1786 Metaphysical Foundations, where the idea of dynamical cosmic aether figures in Kant’s a priori classification of the special properties of matter and in his defence of dynamical explanation in general.[10] The main point to note here regarding this common ground between the Opus postumum and the Metaphysical Foundations is this: The crucial elements of the dynamical æther theory that Kant eventually employed in the Opus postumum in order to construct his systematic sketches for a transitional science are all elements that predate the account of reflective judgement and the principle of nature’s formal purposiveness that was first published in the Critique of Judgement.[11] 

To be sure, giving this chronological factor its proper due does not require us to suppose that the origin of the transition project is necessarily divorced from Kant’s reflections on the connection between the idea of nature’s formal purposiveness and the problem of the systematic character of physics.[12] By the same token, though, the available textual evidence is such that there is simply no good reason to interpret that origin as something separate from Kant’s efforts to revise his theory of matter in view of the explanatory centrality of the concept of physical æther. In other words, even if we accept that Kant had discussed the need for a transitional scientific discipline by autumn of 1790 at the latest, this cannot suffice to establish that the transition was originally detached from the architectonic issues raised by Kant’s dynamical theory of matter and its revision. For the examination of the oldest manuscript leaves of the Opus postumum shows that it is at least as plausible to maintain that Kant, by 1790, was already working on a fundamental revision of his 1786 Dynamics as it is to insist on the linkage between the Critique of Judgement and the idea of transition.[13] And if this is true, then Förster’s chronological ordering strategy can by no means exclude the competing type of explanation of the transition’s origin considered above.[14] 

Moreover, since this type of explanation does support the notion that ‘transition’ and ‘gap’ designate two sides of the same undertaking, I conclude that Förster’s strategy cannot successfully support his challenge to the historically standard interpretation of the relationship between the transition project and the gap in Kant’s system of Critical philosophy. If we consider the semantically natural (not to mention syntactically compelling[15]) way of reading the lines quoted above from Kant’s 1798 letter to Garve, we can see that this kind of interpretation is well enough founded to begin with. At the same time, we can also see that Förster’s very own scholarly contribution is exactly what shows that the standard interpretation cannot be regarded as a mere dogma of Kant scholarship. For the main upshot of Förster’s quite persuasive chronological argument is that it supports this kind of interpretation by enabling us to understand how Kant’s transition project is inseparably linked to the 1780s revisions in his dynamical theory of matter.

Let us return to The Post-Critical Kant and its account of the gap in Kant’s system. As we have seen, 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. Like Förster, Hall holds that the gap does not originate in Kant’s concern with the revisions to the 1786 Metaphysical Foundations which go hand in hand with the development of his theory of matter in the Opus postumum. Instead, according to Hall, Kant’s acknowledgement of the gap in his Critical system stems from his recognition that the Analogies of Experience are based on an inadequate theory of substance. Specifically, Hall argues, the gap derives from Kant’s recognition that his treatment of the transcendental conditions of unified objective experience in the Analogies generates a dilemma because of his adherence to two distinct conceptions of substance.

Now it is one thing to maintain that Kant’s treatment of transcendental conditions in the Analogies of Experience is inadequate, or indeed incoherent, on account of his failure to distinguish properly between two conceptions of substance and to draw out the implications of this distinction. But it is another thing altogether to claim that the inadequacy of this treatment is what Kant was directly addressing when he referred to the gap in his system of Critical philosophy in conjunction with the problem of a transition between the metaphysical foundations of natural science and physics. To support this latter claim, Hall would have to do two things in order to counter the above-mentioned upshot of Förster’s chronological argument. First, he would have to provide a detailed analysis of the overall development of Kant’s æther theory in the parts of the Opus postumum written up to autumn of 1798. Second, he would have to show how this analysis rules out the historically standard view of the transition/gap relation.

The question, then, is whether The Post-Critical Kant offers enough nuts-and-bolts treatment of Kant’s late version of his dynamical theory of matter to accomplish either of these tasks. I think the answer has to be that it does not. Hall does provide some analysis of various developmental features of Kant’s æther theory during the 1780s and 1790s, mainly in the second chapter of his book. Yet as far as I can see, nothing that he asserts or cites in this chapter (or elsewhere) does damage to the standard view. I therefore conclude that Hall’s understanding of the gap problematic in Kant’s Critical philosophy lacks effective support.

I also hold that there is nothing in the manuscripts of the Opus postumum written after 1798 that calls into question the historically standard view of the transition/gap relation, i.e. the view most obviously consistent with Kant’s own remarks on this relation. This claim, of course, demands a discussion of the overall development of Kant’s dynamical æther theory that carefully considers the nuances in his characterisations of his late transition project, especially in connection with the profound changes that this conception seems to undergo in the manuscripts composed after Übergang 1–14. But this sort of discussion goes far beyond what can be undertaken here. So I end this phase of my comments by stating that I am not convinced by Hall’s interpretation of the gap in Kant’s system of Critical philosophy. In my judgement, Hall’s account of Kant’s own view of this gap remains unsubstantiated; and I do not believe that this particular account can be given firm textual support through analysis of the arguments that Kant actually offers in the Opus postumum. In my view, then, there is just no textually plausible reason to hold that the gap to which Kant refers in his autumn correspondence of 1798 is anything other than the architectonic shortcoming that is supposed to be remedied by the completion of the Opus postumum’s transition project, i.e. the project which requires a coherent dynamical theory of matter based on the idea of physical æther as a universal plenum of materially constitutive forces.

3. Substances and Substance

The previous section was primarily concerned to expose the inconsistency between Kant’s characterisations of the gap in his metaphysics of nature and Hall’s view of its systematic location. But my considerations on this architectonic topic have essentially amounted to a brush-clearing exercise. They are intended to deal with the gap problematic in Kant’s late philosophy by clearing the field to the point where we can start digging into a substantive issue of far greater philosophical importance. This is the question of ‘substance vs. Substance’ as it pertains to the Analogies of Experience and the Opus postumum’s æther deduction.

As it happens, there is a good deal of overlap between Hall’s approach to this question and my own. I was therefore somewhat surprised to read the following remark in the first chapter of The Post-Critical Kant:

Both Edwards and Westphal spend some time discussing Kant’s arguments against empty space in the Third Analogy and how these arguments support an omnipresent and dynamical view of substance. Even so, they fail to detect any tension within Kant’s theory of substance. See Edwards, Substance, Force, and the Possibility of Knowledge, 26–43 and Westphal, Kant’s Trancendental Proof of Realism, 80–82. (p. 65, note 20)

I shall let Kenneth Westphal speak for himself regarding his contribution to our alleged failure. For my part, let me set the record straight by making several very brief observations: I do not maintain that there is no tension in Kant’s theory of substance. In the book cited by Hall, I call attention to exactly this point when treating the relationship between the Third Analogy’s argument against empty space and the First Analogy’s considerations on the substratum of time determination (see Edwards 2000:29n24). More significantly, it may be noted that this work as a whole revolves around the problem of substance presented by the relationship between (i) Kant’s dynamical theory of matter, with its inherently monistic conception of æther qua universal force continuum, and (ii) Kant’s theory of the dynamical community of substances (commercium substantiarum). In fact, my overarching aim when tracing the developmental lines of this relationship back to the Essay on Living Forces of 1746 was to show why Kant, in the final fascicles of the Opus postumum, ends up dealing with the question of Spinozism when he attempts to come to grips with various implications of his dynamical æther theory as an inescapably monistic theory of material substance. Thus, the notion that there are tensions in Kant’s theory of substance is something that I took to be simply too obvious to belabour at any given point in the book’s overall argument.

That said, there are some fundamental differences between my approach to the substance vs. Substance problematic and Hall’s. My remaining comments will bring out the nature and the implications of these differences in two main stages: I shall briefly sketch the pivotal developments in Kant’s philosophy of material nature that give rise to that problematic.[16] In view of these developments, I shall then show why Kant had good reason to deal with it in the framework of his dynamical æther theory.

The essential task of his dynamical theory of matter is one that Kant shares with other representatives of dynamistic natural philosophy in the eighteenth century.[17] It is the endeavour to explain corporeal nature in accordance with the notion that matter is constituted through attractive and repulsive forces. In 1755, Kant makes use of Newtonian forces of attraction and repulsion when working out the general æther theory provided by De igne as well as the theory of cosmogenesis found in the Universal Natural History.[18]

But it is in the Monadologia physica of 1756 that we encounter Kant’s first concerted attempt to work out a comprehensive theory of matter based exclusively on dynamistic assumptions. Kant grounds this attempt in a monadological view of substance, thus explicitly calling attention to the historical connection between his theory of matter and Leibniz’s metaphysics of nature. Contrary to Leibniz, however, Kant wants to demonstrate that metaphysical first principles of natural philosophy require the conception of the monad as a physical unit. Such principles, according to Kant, do not involve the Leibnizian supposition that the monad’s function as an independent source of substantial activity must ultimately be understood in terms of a force of representation or of appetition (vis repraesentativa, vis appetitiva).[19] Physical monadology, Kant maintains, must explain the constitution of physical bodies by employing the notion that each of the fundamental entities of which bodies are composed generates a sphere of activity (sphaera activitatis) through the self-limiting interplay of its attractive and repulsive forces.

After the Monadologia physica, Kant does not provide a fully systematised published account of his thinking on the theory of matter until the Metaphysical Foundations of Natural Science of 1786. Nonetheless, there are number of handwritten fragments from the 1770s that shed considerable light on what happens to the dynamical theory after the early physical monadology.[20] In his 1770s Reflections on Physics, Kant continues to demonstrate his concern to work out a comprehensive dynamical theory of matter based on the supposition that matter, as we can cognize it, is constituted through the interplay of attractive and repulsive forces. Yet there is also a fundamental difference between Kant’s early physical monadology and the dynamical conception of the 1770s. This difference has to do with the central role played by physical aether in the explanation of material nature.

The view of physical aether as an imponderable elastic matter is an abiding characteristic of Kant’s philosophy of nature throughout the course of its development. We find elements of this view in Kant’s earliest published work, the Essay on Living Forces of 1746 (see GSK, AA 1:29.4–14, 115.6–10). It also features prominently in the general aether theory of De igne (1755) (see e.g. DI, AA 1:376.18–377.18). Additionally, the view is integrated with the first systematic version of the dynamical theory of matter given in the Monadologia physica (see MonPh, AA 1:487.14–18). In Kant’s physical monadology, however, æther plays a merely peripheral role in the dynamistic account of material nature. It is this peripheral status that changes markedly in the 1770s Reflexionen. By the mid-1770s, Kant comes to maintain that the whole of cosmophysical space must be thought of as continuously filled by an elastic, expansive, and all-penetrating material medium. Moreover, he asserts that this cosmic æther must be understood as a materially omnipresent entity that serves as the generative source of all physical bodies and corporeal formations as well as a ground of causal community throughout the entire universe (see Refl., AA 14:295.5–7, 343.1–2).

Given his conception of the universal efficacy of physical æther, Kant is confronted with questions concerning his cosmic matter’s internal constitution as well as the ontological standing of corporeal particulars included in its field of activity. One place where Kant addresses these questions is found in a passage from Reflexion 44:

Wenn die Welt comparativ Unendlich ist, so hat der durch die gravitation condensirte æther allenthalben gleiche Dichtigkeit […]. Die Materien können als so viel verschiedene anziehende Punkte angesehen werden, aber von verschiednen Graden, nach deren Maaße ihre Masse ein verdichteter æther ist, und so ist æther nicht eine besondere Art Materie, sondern (sofern die) was die expansibilität betrift undurchdringlichkeit betrift, sondern alle Materien bestehen aus æther, der auf in verschiedenen Graden angezogen wird. Diese Anziehung ist nicht die der gravitation, sondern welche die Zitterungen des æthers hemmt. (Refl, AA 14:334.1–336.6)

If the world is comparatively infinite, then the æther which is condensed by gravitation has everywhere the same density […]. Matters can be regarded as so many different attractive points, according to whose measures there is a thickened æther, and hence æther is not a special kind of matter, as concerns impenetrability, but rather all matters consist of æther, which is drawn together [angezogen] in different degrees. This attraction is not that of gravitation, but rather that which checks the tremors of the æther. (trans. mine)

Kant works here with the idea that there is a single force of repulsion that furnishes the ground of all material reality.[21] He also introduces what can be called the collective and distributive views of attraction.[22] The collective view of attraction pertains to the Newtonian idea of universal gravitation. On Kant’s interpretation of this idea, attractive force acts formatively on the whole of the cosmic æther. Considered distributively, however, attraction also proves to be a short-range material force that acts to check the æther’s wave action, thus limiting the dispersive effects that repulsion has on basic material particulars. These material particulars themselves are thought of as points from which attractive force is exerted in such a way that material masses or composite bodies are formed.

The idea of æther as the material basis of a universal system of dynamical interactions furnishes the foundation for the monistic account of material reality that Kant addresses in Reflexion 44. Thus, long before the Opus postumum Kant shows himself willing to explore what follows from the supposition that matter, as we can know it, must be understood as a continuum of the forces that causally determine the whole of physical space. According to this supposition, corporeal particulars are heterogeneous features of a universal material plenum. They can be represented using the notion of individual force centres, or focal points from which force is exerted. Their physical reality, however, is intelligible only with reference to the æther’s all-encompassing field of activity—a field internally structured in virtue of the limitations imposed on the expansive force of repulsion by the bifold force of attraction. Kant thus puts in place the key elements of a dynamical theory of matter that builds on the concept of a universal force continuum.

If we compare the conception of physical reality evidenced in Reflexion 44 with that at issue in the monadology of 1756, then we can clearly discern the tendency toward a radical change in the thematic orientation of Kant’s dynamical theory. By the mid-1770s, physical monads no longer serve as fundamental entities in Kant’s account of material nature. While Kant makes use of the notion of individual centres of force exertion, he employs that notion heuristically as a means of representing how corporeal entities and systems of interacting composite bodies can emerge from a universal material ground. His emphasis on the inclusive substantial reality of a single matter that fills space goes hand in hand with the denial of the causal and ontological self-sufficiency of individually identifiable substances.[23]

Neither the explicitly cosmological orientation nor the metaphysical ramifications of the 1770s æther theory is readily apparent in the version of the dynamical theory of matter that Kant offers in the second part of the Metaphysical Foundations of Natural Science. In the Dynamics of the Metaphysical Foundations, Kant lays out the elements of a theory of matter that conforms to his previous repudiation of the physical monad as the fundamental entity relevant to scientific explanation. But the idea of physical æther as a universal continuum of moving forces and as substance in space is not part of Kant’s core exposition of the concept of matter according to its dynamical definition. Although this idea by no means disappears from Kant’s account of the principles of dynamical explanation, it has a merely subsidiary theoretical status.[24] It is not methodologically central to the Dynamics’ portrayal of material forces and its specification of the metaphysically basic properties of matter.

The status of the dynamical æther concept, however, changes again soon after the publication of the Metaphysical Foundations in 1786, when Kant’s critics made him aware of the highly damaging flaws in the deductive procedure of the Dynamics.[25] Striving to remedy these flaws, Kant again makes the role of physical æther central to his concern with the dynamical explanation of the physically real: The earliest fascicles of the Opus postumum very clearly demonstrate Kant’s renewed engagement with the metaphysical assumptions underlying the 1770s version of the dynamical theory. In the Opus postumum, the concept of cosmic æther once again becomes the thematic centrepiece of Kant’s considerations on the dynamical theory of matter and the metaphysical foundations of natural philosophy. The æther theory of the Opus postumum thus represents an extension of the type of dynamical theory at issue in the 1770s Reflexionen on Physics. Although Kant connects his theory with updated appropriations of contemporaneous research in the physical sciences, his basic views on physical æther remain the same as those worked out in the 1770s. In the Opus postumum we find the same description of æther as an elastic, imponderable, all-penetrating, and expansive medium, and as a universal material plenum. Kant also characterises physical æther as a ground of the community of corporeal entities, as the highest ground of corporeal reality in space, and as the generative source of all corporeal formation and systems of interaction.[26] Most importantly, however, Kant endeavours to put in place the conceptual framework for a comprehensive account of the physically real based on the idea of a universal force continuum. This project has its roots in Kant’s earliest work on the philosophy of nature, and the dynamical æther theory of the Opus postumum gives evidence for a remarkable undercurrent of continuity in Kant’s thought concerning the metaphysical foundations of natural science.

So what exactly does this undercurrent have to do with the substance vs. Substance problematic that Hall locates in the transcendental part of Kant’s metaphysics of nature? Let us approach this question in view of a textual fragment from 1769 that Erich Adickes placed in volume 17 of the Academy Edition under the heading of Kant’s Reflexionen on Metaphysics:

Man kann annehmen, daß die Bewegung eines Korpers nur eine successive Gegenwart einer großen Wirksamkeit der impenetrabilitaet im Raume sey, wo nicht die Substantz den platz verändert, sondern diese Wirkung der impenetrabilitaet in verschiedenen Orten nach und nach succedirt, wie bey dem Schalle die Luftwellen. Man kann auch annehmen, daß es im Raume gar keine substantzen gebe, sondern eine großere oder kleinere Wirksamkeit einer eintzigen obersten Ursache in verschiedenen Örtern des Raumes. Daraus würde folgen, daß die Materie unendlich theilbar wäre. (Refl 3986, AA 17:376.24–377.6)[27]

One can suppose that the motion of a body is merely the successive presence of a greater efficacy of impenetrability in space, where it is not substance that changes its place, but rather this effect of impenetrability gradually progresses [succedirt] in different locations, just as air waves do in the case of sound. One can also suppose that there are no substances at all in space, but rather a greater or lesser efficacy of a single highest cause in different locations of space. It would follow from this that matter is infinitely divisible. (trans. mine)

In this Reflexion of 1769, Kant works with three key suppositions that concern the relationship between materially constitutive force, bodies, and substance: (1) Bodies are comprehensible as particular spatial fields determined by relatively greater concentrations of repulsion.[28] (2) The local motion of these corporeal particulars can be understood in terms of the wave action of a substance that does not change its place. (3) There is a single highest cause whose efficacy in different locations obviates the need to suppose that there are particular substances in space. Thus, if we interpret the 1769 Reflexion in view of Kant’s 1770s dynamical theory, it is evident that the idea of physical æther as a universal force continuum is what ties together all three of the suppositions just mentioned.[29] For it allows us to understand the connection between force-constituted ‘body’, the action of ‘a substance’ that does not change its spatial location, and efficacy of ‘a single highest cause’ that counterweighs the tenet of pluralism in the metaphysics of material substance. Specifically, it enables us to see how Kant’s field-theoretical conception of body goes hand in hand with his dynamistic view of the universal causal efficacy of a single material substance as well as with his corresponding thought that there may be no multiplicity of substances in space.

Clearly, then, Hall is entirely right to underscore the substance vs. Substance problematic that is built into Kant’s dynamical æther theory. Kant himself addresses it when setting the stage for this theory’s early formulation. Nonetheless, I think that there are some crucial difficulties in Hall’s particular account of that problematic as it bears on the relationship between the First Critique’s Analogies of Experience and the developments in Kant’s transcendental theory which take place in the Opus postumum.

One difficulty should be obvious from the criticism offered above in the first section of my comments. As we have seen, Hall contends that the gap in Kant’s system of Critical philosophy is a function of the dilemma for Kant’s account of substance that derives from his failure to pull apart two mutually irreducible conceptions of substance, i.e. the distinct conceptions which correlate with (i) the category of substance, which has its proper application to ‘substances’, and (ii) the concept of ‘Substance’ furnished by Kant’s dynamical idea of physical æther. Thus, if my criticism of this view of the gap in Kant’s system is correct, the substance vs. Substance problematic that underlies the Analogies of Experience cannot be what Kant has specifically in mind when he refers to the architectonic shortcoming in his metaphysics of nature.

Getting clear about this point, of course, does nothing to address the metaphysical issue that underlies Kant’s dealings with the different conceptions of substance just mentioned. But it does clear the path for taking up a second crucial difficulty in Hall’s treatment of the relationship between these two conceptions: Just why is it that the proper application of the category of substance should be restricted to substances as particular substrata of time determination? In other words, why is it that the a priori concept of substance furnished by Kant’s dynamical idea of physical æther (i.e. the rational concept of a universal continuum of materially constitutive forces) cannot simply be specified in terms of the features of the category of substance?

Given Hall’s particular view of the gap in Kant’s Critical philosophy, it seems to me that questions like these should be of central concern to his treatment of the aforementioned dilemma for Kant’s theory of substance, especially as it pertains to the relationship between the First and Third Analogies of Experience. As far as I can see, though, such questions are not directly raised in the course of his book’s argument; and it is not obvious that this argument contains the resources needed for answering them.[30] Let me therefore explain what I think is fundamentally at issue.

As a pure relational concept of the understanding, the category of substance is that “Of Inherence and Subsistence (substantia et accidens)” (A80/B106). It is thus the a priori concept of the relation of inherence and subsistence understood as the relation between accident and substance. Why, then, should this concept of substance’s relation to its accidental determination(s) not be applicable to both ‘substances’ (as appearances [cf. A188/B231]) and ‘Substance’ (qua universal force continuum) 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])?  

I shall not pretend to provide an adequate response to this last question here. But the following thoughts should at least put us in a position to discern what the underlying metaphysical problem is and what it entails for Kant’s theory of substance as well as for the related developments in his transcendental theory that are apparent in the later fascicles of the Opus postumum.

The problem itself can be stated quite simply, as follows: (1) The dynamical theory of matter requires that force (or forces) must be thought of as that which constitutes, i.e. is, material substance. (2) The conceptually coherent formulation of such a theory therefore calls into question the substance/accident scheme of things that the category of substance is supposed to ground.

For insight into the inferential connection between these two propositions, let us consider the criticism of Spinoza’s definition of substance that Kant offers in the context of his polemical treatment of Eberhard in 1790.[31] Kant rejects there the proposition “the thing (the substance) is a force” since he considers this to be “in conflict with all ontological concepts” (ÜE, AA 8:224n.24–6). Accordingly, he holds that a metaphysical theory which insists on the identity of force and substance must be one that forfeits the very concept of substance. Specifically, it must give up the ‘concept of […] inherence in a subject’ (ÜE, AA 8:224.27–8) and put the concept of causal dependency in its place, which is exactly what Spinoza in fact did when he made “universal active [wirkende] force itself into a substance” (ÜE, AA 8:224.31–2). Spinoza thus effectively conflated the two distinct categorial functions of the understanding in question:

Eine Substanz hat wohl außer ihrem Verhältnisse als Subject zu den Accidenzen (und deren Inhärenz) noch das Verhältniß zu eben denselben, als Ursache zu Wirkungen; aber jenes ist nicht mit dem letzteren einerlei. Die Kraft ist nicht das, was den Grund der Existenz der Accidenzen enthält (denn den enthält die Substanz): sondern ist der Begriff von dem bloßen Verhältnisse der Substanz zu den letzteren, so fern sie den Grund derselben enthält, und dieses Verhältniß ist von dem der Inhärenz gänzlich unterschieden. (ÜE, AA 8:224.33–9)

A substance does indeed have, besides its relation as subject to the accidents (and their inherence), also the relation to these of cause to effects. But the former relation is not identical with the latter. Force is not that which contains the ground of the existence of the accidents (for the substance contains this ground). Rather, it is the concept of the mere relation of substance to the accidents, insofar as it contains their ground, and this relation is completely different from that of inherence. (trans. mine)

Whether or not Kant gives (in 1790) an accurate assessment of the basic assumptions of Spinoza’s philosophy of substance is beside the point as far as our present purposes are concerned. His grappling with Spinoza is of interest to the evaluation of Hall’s book only to the extent that it sheds light on the fundamental metaphysical problem involved in Kant’s use of the concept of materially constitutive force throughout the entire history of his dynamical theory of matter, i.e. the developmental history that stretches from the Monadologia physica to the Opus postumum. The problem is this: If force is what constitutes matter as substance in space, then (contrary to Kant’s view of the proper relation between force and that which contains the ground of accidents’ existence) the concept of substantial force that the dynamical theory requires cannot be the concept of the mere relation of substance to its accidental determinations.

There is solid evidence for Kant’s concern with this problem in the Opus postumum, and there is very good reason for his concern.[32] By the time he composes the manuscript segments gathered under the title of Übergang 1–14, the stakes are nothing less than the categorial resources that his transcendental dynamics can command in order to provide an alternative to Spinozism as he understands it. Hall’s book has the distinct merit of bringing us very close to the question of these resources.

Invited: 24 October 2014; received: 22 July 2016; revised: 21 October 2016.


[1] The correctness of this natural reading seems confirmed by the following passage from the letter to Kiesewetter of October 19th, 1798: “Mein Gesundheitszustand ist der eines alten, nicht kranken, aber doch invaliden; vornehmlich für eigentliche und öffentliche Amtspflichten ausgedienten Mannes, der dennoch ein kleines Maas von Kräften in sich fühlt, um eine Arbeit, die er unter Händen hat, noch zu Stande zu bringen; womit er das critische Geschäfte zu beschließen und eine noch übrige Lücke auszufüllen denckt; nämlich »den Übergang von den metaph. A. Gr. der N. W. zur Physik«, als einen eigenen Theil der philosophia naturalis, der im System nicht mangeln darf, auszuarbeiten” (Br, AA 12:258).

[2] See Förster (1987).

[3] According to this interpretation, the transition represents in effect an ad hoc solution to the systematic difficulties that arose for Kant’s conception of metaphysical knowledge when Kant admitted the fundamentally flawed character of the theory of matter presented in the Metaphysical Foundations of 1786. See Tuschling (1971:31–2, 61–5, 157–60).

[4] As Tuschling points out (2000, 31and 46), Kant did not mention the need for such a project even when he acknowledged that his dynamical explanation of variation in the density of matter—a central point in the explanation of key material properties—was circular. See Kant’s letter to J. S. Beck of October 16th, 1792 (Br, AA 11:375.28–377.33, especially 376.30–377.4).

[5] Note well my agreement with Hall on this particular point.

[6] In addition to Tuschling (1971), see Edwards (2006:163n14) and Ermundts (2004:15–26, 150–5).

[7] Leaf 25 of the Opus postumum’s fourth fascicle includes Kant’s handwritten excerpt from the first review of the Metaphysical Foundations of 1786, an anonymous review that was published in the December 2nd, 1786 edition of the Göttingsche Anzeigen für gelehrten Sachen, pp. 1914–18. For discussion concerning authorship, see Tuschling (1971:47–56) and Fambach (1976:34).

[8] See OP, AA 21:417.18–418.23, 423.12–425.21, 428.14–30, 443.24–444.15, 452.16–453.5, 466.21–467.11, 468.16–469.10.

[9] See e.g. OP, AA 21:373.1–375.27, 378.7–383.34, 410.1–20.

[10] See MAN, AA 4:426.12–34 (also 563.39–564.9), 533.21–534.18. For detailed discussion, see Edwards (2000:132–44).

[11] Moreover, the basic assumptions of Kant’s dynamical aether theory are quite clearly recognizable at least as early as the Reflexionen on Physics that stem from 1770s. For discussion of the overall development of Kant’s dynamical æther theory, see Edwards (2000:112–44, 152–69) and Förster (2000:24–47, 61–74).

[12] I am inclined to think, however, that this connection does not become an issue of key systematic significance in the Opus postumum before Elem.Syst. 1–7, when Kant comes to focus his attention on the account of a world system of material formations as one of two main parts of the Transition’s system of the moving forces of matter (see e.g. OP, 21:155.9–14, 197.10–24, 199.23–201.1). For further consideration of this view, see Edwards (2004:162n14). Rollmann (2015) provides the best analysis of this aspect of Kant’s late thought.

[13] For a general treatment of Kant’s reasons for dissatisfaction with the Dynamics of the Metaphysical Foundations (1786), see Edwards (2000:138–44).

[14] I should also point out in this context that the standard interpretation is quite capable of accommodating research into the textually specific links between the Opus postumum and the Critique of Judgement. On this, see Edwards (2004:188n72), especially the comments on ¶ 58 of the Critique of Judgement and the background references to Cinzia Ferrini’s work.

[15] Consider again the second sentence of the quotation: “Sie [i.e., the task or problem that concerns the transition from the metaphysical foundations of natural science to physics] will aufgelöset seyn; weil sonst im System der crit. Philos. eine Lücke seyn würde.”

[16] The sketch of these developments tracks the account given in Edwards and Schönfeld (2006), which in turn summarises chapter 7 of Edwards (2000).

[17] For discussion of the Newtonian and Leibnizian roots of eighteenth-century dynamical theories, see Edwards (2000), Chap. 6. See also Schönfel (2000:17–95, 111–17, 138–54, 161–79).

[18] For details, see Edwards (2000:114–18) and Schönfeld (200o:84–9).

[19] On Kant’s relation to Leibniz as well as to Chrisitian Wolff, see Edwards (2000:63–72) and Schönfeld (2000:131–79).

[20] The relevant Reflexionen are found in volume 14 of the Academy Edition of Kant’s works. Erich Adickes’s extensive editorial commentary and exposition of sources makes this volume arguably the most important collection of materials pertaining to the overall development of Kant’s philosophy of nature.

[21] Regarding this idea, see Refl, AA 14:295.5–7, 343.1–2.

[22] Regarding the use of ‘distributive’ and ‘collective,’ see AA 4:526.12–35; 14:287.1–288.2; Reflexionen 4046, 4149, 4169, 4490, 5840 (AA 17 and 18).

[23] On Kant’s elimination of the monadological interpretation of substance from the philosophy of material nature, see Refl., AA 14:153.12–14, 161.1–2. For discussion, see Edwards (2000:128–32).

[24] See jointly MAN, AA 4:526.12–35, 534.5–535.10, 563.39–564.9.

[25] On this, see Tuschling (1971:39–61) and Förster (2000:33–47).

[26] For extensive lists of references to the relevant passages in the Opus postumum, see Edwards (2000), Chap. 8, notes 25, 26, 28, 36, 37, 38, 40, and 41.

[27] For criticism of Adickes’s contextual placement and interpretation of this passage, see Edwards (2000:176, 180–1).

[28] From 1756 onwards, Kant always explains impenetrability in terms of the effect of repulsive force. In the passage under consideration, his characterisation of the body as the ‘presence of a greater efficacy of impenetrability in space’ necessarily presupposes that the dispersive effect of repulsion is limited by attractive force.

[29] I have argued that we must interpret this reflection in connection with the development of Kant’s 1770s æther theory. See the references to Edwards (2000) in note 26.

[30] While Hall comes close to raising the essential questions (see pp. 59–60), he ultimately does not come to grips with them. This evidently has to do with his concern to show (see p. 59) that ‘substances’ cannot coherently be thought of as accidents or as accidental properties of ‘Substance.’ I confess that I cannot see how this could ever be an issue on Kant’s own terms.

[31] This paragraph’s analysis of the critical broadside that Kant levels against Spinoza’s definition is adapted from Edwards (2000:162–3).

[32] See (in chronological order) OP, AA 21:311.26–312.7, 338.8–11, 350.22–9, 541.20–543.11; AA 22:327.4–8, 346.2–10, 349.21–4, 358.1–9, 360.3–18, 360.26–361.4, 378.18–24, 402.26–403.10, 471.20–472.8, 475.26–30, 508.14–509.11, 514.21–5, 523.19–33, 535.10–15, 438.17–26, 450.14–16. The majority of these passages involve the attempt to show that what we ordinarily call substances are actually particular moving forces, while substance as such is nothing less than the collective whole of dynamical matter. Much of what Kant says is broadly consistent with the account of the relationship between physical æther and material particulars that we encounter in work from the 1770s. But things get to be remarkably complicated when he deals directly with the substance/accident issues raised by this kind of account (see, for instance, OP, AA 22:394.2–18).



Edwards, J. (2000), Substance, Force, and the Possibility of Knowledge in Kant’s Philosophy of Material Nature (Berkeley: University of California Press).

——— (2004), ‘One More Time: Kant’s Metaphysics of Nature and the Idea of Transition’, in C. Ferrini (ed.), Eredità kantiane (1804–2004): Questioni emergenti e problemi irrisolti (Napoli: Bibliopolis), pp. 155–88.

——— (2008), ‘“Transition” and “Gap” in Kant’s Opus postumum’, in V. Rohden et al. (eds), Akten des 10. internationalen Kant-Kongresses, vol. 5 (Berlin and New York: de Gruyter), pp. 231–43.

Edwards, J. and M. Schönfeld (2006), ‘Kant’s Material Dynamics and the Field View of Physical Reality’, Journal of Chinese Philosophy 32: 109–23.

Emundts, D. (2004), Kants Übergangskonzeption im Opus postumum (Berlin and New York: de Gruyter).

Fambach, O. (1976), Die Mitarbeiter des Göttingschen Gelehrten Anzeigen (Tübingen: Universitätsbibliotek).

Förster, E. (1987), ‘Is there “a Gap” in Kant’s Critical System?’, Journal of the History of Philosophy 25: 536–55.

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

Rollmann, V. (2015), Apperzeption und dynamisches Naturgesetz in Kants Opus postumum: Ein Kommentar zu ‘Übergang 1–14’ (Berlin and New York: de Gruyter).

Schönfeld, M. (2000), The Philosophy of the Young Kant: The Pre-Critical Project (Oxford: Oxford University Press).

Tuschling, B. (1971), Metaphysische und transzendentale Dynamik in Kants Opus postumum (Berlin and New York: de Gruyter).

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

© Jeffrey Edwards, 2016.

Jeffrey Edwards is Associate Professor of Philosophy at Stony Brook University, New York. He is the Stony Brook Director of the Transatlantic Collegium of Philosophy. Edwards’s areas of concentration are in Kant and the history of modern philosophy and he has published widely on Kant’s relations to the history of modern science, metaphysics, ethics and political philosophy. He is the author of Substance, Force, and the Possibility of Knowledge in Kant’s Philosophy of Material Nature (Univ. Calif. Press, 2000). He is also the editor, together with Allegra de Laurentiis, of The Bloomsbury Companion to Hegel (Bloomsbury 2015). His next monograph Autonomy, Moral Worth, and Right. Kant on Obligatory Ends, Respect for Law, and Original Acquisition is forthcoming from de Gruyter.