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


By Kenneth R. Westphal 

In both structure and substance, Kant’s posthumous manuscripts on transcendental philosophy of nature (henceforth Opus postumum) are deeply challenging, problematic and controversial. Bryan Hall bravely ventures to make sense of them in his recent book, The Post-Critical Kant: Understanding the Critical Philosophy through the ‘Opus Postumum’. In his own comments on Hall’s book for this forum, Jeffrey Edwards ably summarises the main thrust of Hall’s interpretation and re-examines how Eckart Förster’s chronological findings reinforce, rather than undermine, Burkhard Tuschling’s interpretation of Kant’s late manuscripts, an interpretation Edwards (2000; 2004) has significantly augmented. Edwards’s re-examination of Förster’s chronology matters to assessing Hall’s views because Hall relies on Förster’s chronology to counter Tuschling’s interpretation. In re-examining this chronology, Edwards also highlights important features of Kant’s thinking in these manuscripts, features which count against Hall’s views.

Accordingly, I shall forego summarising Hall’s views and focus instead on more methodological issues. These raise further substantive issues regarding how, or whether, Hall has correctly identified the problems within the official Critical philosophy to which Kant purportedly responds in his late manuscripts on transcendental philosophy of nature. These substantive issues reveal that Hall has misunderstood both the substance and the methods of Kant’s Critical philosophy, thus confounding his treatment of Kant’s Opus postumum.


To sort “good interpretations from bad ones” Hall proposes these four interpretive conditions:

1) A good interpretation should be maximally consistent with the text. This includes not only providing textual evidence for the interpretation, but also addressing texts that seem to conflict with the interpretation. As I will argue, this requires not only taking into account Opus postumum, but Kant’s Critical-era texts as well.

2) A good interpretation should make Kant maximally consistent with himself. Although one could make a textual case that Kant simply contradicts himself in Opus postumum, a good interpretation should, as best as possible, make sense of these apparently conflicting passages. Furthermore, since Kant believes the transition project fills an important gap within the Critical philosophy, a good interpretation should try to make the post-Critical Kant as consistent as possible with the Critical Kant. Otherwise, one risks filling the gap in the Critical philosophy only by sacrificing the Critical philosophy itself.

3) A good interpretation should be philosophically plausible. Interpretations that make Kant’s view philosophically incoherent or fail to solve the philosophical problems they identify should be rejected in favor of interpretations that are philosophically coherent and fruitful.

4) A good interpretation should reflect Kant’s intent for Opus postumum. As mentioned above, Kant considered Opus postumum the keystone of his philosophical efforts and he believed that the transition filled an important gap within the Critical philosophy. Holding all else equal, an interpretation that makes good on Kant’s intent should be preferred to interpretations that are deflationary or hold that Kant misunderstood his own philosophical project. (pp. 5–6)

The issues regarding Kant’s “intent” in Opus postumum (condition 4) all turn upon correctly identifying whatever problem(s) Kant thought he had identified within his official Critical corpus, the three Critiques together with the Metaphysical Foundations of Natural Science and the Metaphysics of Morals. The issues regarding the philosophical plausibility of Kant’s Opus postumum (condition 3) require careful assessment of whether Kant is correct about that problem (or about those problems)—or at least whether he could have had persuasive reasons to believe there was such a problem (or were such problems). There is thus no question of whether Kant’s published Critical corpus pertains to the understanding and assessment of his Opus postumum mss. (conditions 1 & 2). In this regard, I regret to say, Hall’s effort is neither coherent nor fruitful, for several reasons.


Kant’s Opus postumum mss. discuss both an unexpected “transition” from metaphysical to physical principles, and an allegedly glaring “gap” in his entire Critical philosophy. These alleged issues appear to have begun separately, though ultimately Kant’s Opus postumum proposes a single solution consisting in his late “transition” project, Übergang 1–14.

Hall states his point of departure in these terms:

In the Preface to the Critique of the Power of Judgment (CJ), Kant claims to have brought his ‘entire critical enterprise to an end.’ Even if the Critical philosophy is itself complete, however, Kant holds that the ‘doctrinal’ task remains of presenting the ‘metaphysics of nature and of morals.’ Although Kant arguably completes the latter task in 1797 with the publication of the Metaphysics of Morals (MM), Kant never published a corresponding Metaphysics of NatureAll we have is the Metaphysical Foundations of Natural Science (MFNS), a ‘special metaphysical natural science’ which determines the empirical concept of matter (the movable in space) in accordance with the ‘transcendental part’ of the metaphysics of nature (MFNS 4:469–470). (pp. 1–2)

Hall’s claim about this lack in Kant’s corpus is incorrect. Kant’s Metaphysical Foundations of Natural Science and his Metaphysics of Morals are corresponding works. Both use the same Critical account of legitimate metaphysics: The a priori specification of the fundamental principles of a logically contingent concept of a specified kind of being. In the former, this is the concept of “matter as the moveable in space”; in the latter, the concept is of “finite rational embodied agent”. The lack of correspondence Hall alleges is merely titular: Kant’s term ‘Anfangsgründe’ appears in the title of Metaphysical Foundations of Natural Science, though not in the title of Metaphysics of Morals. However, Kant’s Metaphysics of Morals has only two parts, ‘The Metaphysical First Principles (Anfangsgründe) of Justice’ and ‘The Metaphysical First Principles (Anfangsgründe) of Virtue’.

In the Critique of Practical Reason, Kant notes that the modal categories of possible free acts (forbidden, permissible, obligatory) provide “the transition from practical principles as such to the practical principles of morals” (KpV, AA 5:67). This is the earliest published mention (1788, nine years prior to the parallel claim in MS/TL, ¶ 45) by Kant of a “transition” from Critical metaphysical principles to their domain of application. This “transition” is not simply a restriction of scope, focussing upon a specifically moral sub-set of practical principles. The main point of Kant’s transition is to move from the purely a priori principles of morals considered up to this point in the Critique of Practical Reason to more specific principles required for a doctrine of morals. This doctrine is, in Kant’s specifically Critical sense, metaphysical. “Metaphysics” in general, Kant holds, is “a system of a priori knowledge from concepts alone” (MS, AA 6:216). If these concepts are a priori, their analysis provides a general metaphysics; if a specific, contingent, empirical concept is also included, the analysis provides a ‘specific’ metaphysics pertaining to that concept (and its instances). In this regard, Kant’s Critique of Pure Reason provides a ‘general metaphysics’ of nature. Kant’s Metaphysical Foundations of Natural Science provides a ‘specific’ metaphysics of nature by a priori analysis of the contingent concept ‘matter’ (MAN, AA 4:470.1–12). Kant’s ‘general’ metaphysics of morals is contained in the Critique of Practical Reason and in the Preface and Introduction to the Metaphysics of Morals. Kant’s ‘specific’ metaphysics of morals results from a priori analysis of the contingent concept of our finite, human form of rational agency, as developed in his Doctrines of Justice and of Virtue.

In both the Groundwork and in the Metaphysics of Morals Kant insists that his pure rational principles of practical reason require “practical anthropology” to be applied to us as human beings, to generate specific moral injunctions or permissions (GMS, AA 4:388, 412; MS, AA 6:216–17). This practical anthropology is a “proper appendix” to Kant’s practical philosophy (MS/TL 6:469); it provides the contingent, determinate concept of our species of finite human rational agency, including pervasive features of our worldly context of action. Though Kant never composed this “appendix”, his examples and analyses of our moral obligations provide much information about it (Westphal 2016a, ¶¶ 11.1, 21, 32, 38). If there is a first and original model for Kant’s “transition” from his Critical metaphysics of nature—comprising both Critique of Pure Reason and Metaphysical Foundations of Natural Science—it must be Kant’s “transition” from his Critical metaphysics of morals—comprising both Critique of Practical Reason and Metaphysics of Morals—to our actual human rights and obligations (both strict and broad; justice and virtue) via his unwritten though not unremarked “practical anthropology”.


Hall argues that Kant requires two quite different concepts of substance within the Analogies:

One concept is of relatively enduring individual empirical objects, or what I call “substances”. The other concept is of a sempiternal and omnipresent material, or what I call “Substance”. Since Kant has only the category (a priori) concept of substance at his disposal in the Analogies, however, I will argue that his theory of substance faces a dilemma and that he lacks the tools, within the context of CPR, which would be necessary and sufficient to resolve this dilemma. Assuming that the three Analogies stand or fall together, if Kant is unable to resolve this dilemma, there will be a significant gap within the Critical philosophy. This gap will lie at the heart of Kant’s project in the Transcendental Analytic and so in the transcendental part of the metaphysics of nature. (p. 24)

(I shall designate Hall’s concept with capitals: SUBSTANCE.) This SUBSTANCE, Hall contends, is required in order to provide for the unity of our experience of nature. This fundamental role Kant’s Opus postumum assigns to a material æther or caloric (Wärmestoff):

Kant recognizes that the transcendental formal conditions for experience that he presents in CPR (space, time, categories, and apperception) are not sufficient to guarantee the unity of experience. In addition to these cognitive conditions, the ether must exist as a transcendental material condition for experience. At the same time, Kant’s a priori proof strategy in the Ether Deduction delivers an a priori concept of the ether that corresponds to Kant’s concept of Substance in the Analogies and is importantly different from the category of substance. Although the Ether Deduction offers an a priori proof for the existence of Substance and provides Kant with the conceptual resources necessary to avoid the dilemma that faces his theory of substance in the Analogies, he must still explain how the a priori concept of the ether is applied for the unity of experience in order to finally bridge the gap in his Critical philosophy. (p. 24)

In order for human experience as a whole to be unified, there must also exist, corresponding to it, a unified causal-dynamic whole, i.e., the ether as a plenum of attractive and repulsive forces. This will complete the transition from a redescribed “metaphysical foundations of natural science” to his very broad conception of “physics”. Far from being separate issues, Kant’s transition project in Convoluts 10–11 and the gap problem are intimately connected and it is only by recognizing both the transcendental material and formal functions of the ether that the transition can be effected and the gap in Kant’s Critical philosophy filled. (p. 25)

These claims challenge the credulity of Critical Kantians, yet Hall contends that we must take them seriously because Kant’s Critical philosophy must not only legitimate our projecting an integrated natural order; Kant comes to believe he can demonstrate that there is such an integrated natural order through an a priori, transcendental proof of a material æther. Hall argues as follows:

Kant discusses the systematic unity of cognitions in the appendix to the Transcendental Dialectic. He says there that the systematic unity of the understanding’s cognitions can only be a projected unity, i.e., a mere idea of reason which cannot be produced by the understanding itself. Reason must attempt, nevertheless, systematically to unite its findings with understanding’s cognition of nature. Since transcendental apperception cannot produce a systematic unity of the understanding’s cognitions, it also cannot produce the systematic unity of nature. Reason can only presuppose such a unity as objectively valid and necessary. This presupposition is itself necessary, however, since without it there would be no coherent use of the understanding:

For the law of reason to seek unity is necessary, since without it we would have no reason, and without that, no coherent use of the understanding, and, lacking that, no sufficient mark of empirical truth; thus in regard to the latter we simply have to presuppose the systematic unity of nature as objectively valid and necessary. (CPR A651/B679)

Kant’s claim here should give the reader pause. If there is “no sufficient mark of empirical truth”, i.e., no guarantee of the “agreement of cognition with its object” (CPR A58/B82), Kant’s whole theory of cognition in CPR might be undermined. (Hall pp. 139–40)

How serious a threat is represented by this modal phrase “might be”?


Clearly, there is a shift in Kant’s late thinking about the modalities of his Critical claims, and about what modalities he can prove transcendentally. Hall notes Kant’s shift in these terms:

Kant’s project changes in Convoluts 10–11 insofar as he believes that he need not merely presuppose but can actually establish a correspondence or harmony between the subject’s cognitions and the systematic unity of nature a priori. The systematic unity of nature is itself deduced a priori in the Ether Deduction. The systematic unity of the subject’s cognitions via the absolute unity of consciousness is established in Convoluts 10–11, as is the harmonization of this absolute unity of consciousness with the systematic unity of nature. Kant’s project, if successful, would dispel the top-down/bottom up problems since there would be no in principle discontinuity between the systematic unity of nature and the subject’s cognition of this systematic unity. (p. 141)

Kant’s transcendental cum metaphysical ambitions grow enormously across the Opus postumum manuscripts. Hall should not have accepted them so unCritically for several reasons, including the following.


Hall should have been alerted to issues about what can and cannot, and what ought and ought not, be “guaranteed” by Kant’s transcendental Critique by Paul Guyer’s (1987) detailed, critical examination of Kant’s transcendental idealism. Guyer’s examination of Kant’s claims about the scope and character of human knowledge has been subjected to much criticism; nevertheless, it contains important philosophical and interpretive insights which surpass most of the subsequent literature. One of these is Guyer’s finding that Kant’s three principles of causal judgement in the Analogies of Experience form an integrated set: none can be used without conjoint use of all three because causal judgements are discriminatory. I highlighted and augmented Guyer’s finding in my own book Kant’s Transcendental Proof of Realism (Westphal 2004, ¶¶ 36–8). This finding remains widely neglected or rejected; Hall simply assumes it (p. 24; see above, Section 3).

In connection with Hall’s construction, Guyer’s single most important finding is that Kant’s transcendental analyses and proofs can establish conditional necessities, that for any apperceptive human being, the necessary a priori conditions of the possibility of self-conscious human experience are satisfied. To explain how those conditions are satisfied, and to prove unconditionally that they are and must be satisfied, requires Kant’s transcendental idealism. However, none of Kant’s arguments for transcendental idealism are valid. These findings I have corroborated and augmented in Westphal (2004). Hall’s exposition neglects these issues and findings.


Perhaps the late Kant “believes” he “can actually establish a correspondence or harmony between the subject’s cognitions and the systematic unity of nature a priori“, as Hall states in the passage quoted in Section 4, but the philosophical question must be whether Kant did or can justify that belief, and if so, exactly how? Otherwise we lapse into mere doxography.


Hall contends (as noted) that

[i]f there is “no sufficient mark of empirical truth”, i.e., no guarantee of the “agreement of cognition with its object” (CPR A58/B82), Kant’s whole theory of cognition in CPR might be undermined. (pp. 139–40)

Now Kant was a fallibilist about cognitive justification, both regarding empirical knowledge (A766–7/B794–5), and—as I have argued en detail several times (Westphal 2004; 2006; 2007)—about his transcendental reflections, analyses and proofs regarding the structure and functioning of our cognitive capacities. Most relevant here, where the concern is “empirical truth” and the (purported) systematic unity of nature, is Kant’s fallibilism about empirical knowledge. “Might be” is relevant to empirical justification only if sufficient justification for empirical knowledge requires eliminating all logically possible alternatives. This is the Cartesian deductivist ideal of infallibilism. Kant’s fallibilism about empirical justification demonstrates that infallibilist ideals of cognitive justification pertain only to strictly formal domains, and are in principle irrelevant to all non-formal domains, including the entirety of morals and of empirical knowledge.

There is no reason to suppose, and excellent reason not to suppose, that Kant’s remark about a “sufficient mark of empirical truth” must be an infallible mark of empirical truth. Truth, accuracy and sufficient justification are plenty for empirical knowledge, without presuming infallibility, as Hall does.


Kant’s Critique of Pure Reason contains an original and incisive semantics of singular, specifically cognitive reference which has important implications for epistemology, philosophy of science and metaphysics.[1] Kant’s cognitive semantics undergirds the following set of distinctions we must consider in any claim to empirical knowledge, or in any cognitive judgement about empirical states of affairs. The following are five distinct (proto-)cognitive achievements:

  1. Description, i.e., predicate concepts, classificatory concepts;
  2. Ascription, i.e., predication of or attribution of characteristic(s) to some particular one has (presumptively) localised;
  3. (Approximately or sufficiently) accurate or true ascription;
  4. Cognitively justified ascription;
  5. Sufficiently cognitively justified ascription.

Only the last class (5) counts as empirical knowledge. (What kinds or extent of cognitive justification suffice for knowledge need not be considered here.[2]) Kant’s point against infallibilism and its appeal to mere logical possibilities to defeat putative cognitive justification is that no mere description (intension), hence no mere logical possibility, is by itself even a candidate cognition; a description can become a candidate cognition only by Someone referring it in some specific way to some (presumptively) ostended spatio-temporal particular. This requires locating the (allegedly) relevant particular within space and time. This is the cognitive-semantic lesson of Kant’s critique of Leibniz in the Amphiboly of the Concepts of Reflection (A260–8/B316–24). Kant’s cognitive semantics achieves the key aim of verification empiricism—proscribing transcendent metaphysical claims—without invoking verificationism! (For concise details, see Westphal 2016b, ¶ 2.) Kant’s cognitive semantics also directly refutes infallibilism about cognitive justification within all empirical knowledge. Hall’s worry about what “might be” is incautiously unCritical.


Hall (p. 24; above Section 3) may be correct—Edwards (2000; 2004) has argued brilliantly that this is correct—that Kant argues that “the ether must exist as a transcendental material condition for experience”. However, the relevant sense of ‘material’ in “material condition for experience” contrasts to ‘formal’ conditions for the possibility of unified, apperceptive human experience, i.e., Kant’s judgemental forms, categories and two forms of sensible intuiting. Kant’s æther is a ‘material’ condition insofar as it exists within space and time, and insofar as it (purportedly) fulfills a transcendentally necessary role in the possibility of human apperceptive experience. This role, Kant indicates in the Third Analogy, is to be a conduit conducting transeunt causal influences between particular interacting substances (A213–14/B260–1). This claim may be puzzling intrinsically (what sort of ‘conduit’ is this, and why do transeunt forces require a conduit, not merely space and time?), and may be very puzzling as the purported conclusion of a transcendental proof. However those puzzles may be resolved, these observations point up a fatal equivocation in Hall’s account: that the æther is (supposed to be) a “transcendental material condition for experience” does not as such mean that this alleged æther is matter in the form of any substance, nor any SUBSTANCE: According to Kant, matter is constituted by a dynamic counter-balance between attractive and repulsive forces, whereas Kant’s æther or caloric consists (officially) only in attractive force.—My surmise is that Kant’s distinction between nature considered formaliter and materialiter (A418–19/B446n.) may help to elucidate in what Critical sense the æther is to be a “transcendental material condition” for our apperceptive experience, without entailing that this æther qua conduit of transeunt forces is any material substance or SUBSTANCE. Yet even if this distinction is relevant, it won’t save Kant’s dynamic theory of matter, for reasons examined in Westphal (2004), ¶¶ 41–51.


If Kant’s aim in the Metaphysical Foundations of the Science of Nature (and the Opus postumum) is to provide the fundamental principles required for Newtonian physics, the æther for which Kant argues cannot be a substance, nor a SUBSTANCE. If Kant’s æther were SUBSTANCE or a substance it would have mass. If it had mass, it would destroy Newton’s precise measures of the masses of orbiting bodies and his entire dynamical explanation of periodic motions. This consideration ultimately ruled out all of Newton’s attempts to devise mechanical explanations of gravitational attractions. Physics today continues to regard gravitational attraction as a fundamental force. Kant’s attempts to grapple with the (alleged) foundations of Newtonian mechanics requires understanding the fundamentals of Newtonian mechanics.[3]


The ‘substance’ which Hall supposes to be sempiternal is—Kant indicates—whatever material substance survives radical transformations within nature, such as combustion (A185/B228). This substance Kant cannot specify philosophically; its constitution instead must be investigated scientifically by chemistry and, much later, nuclear physics. As Weizsäcker (1964) noted, Kant’s First Analogy argues for a conservation principle of nature. This substance as whatever matter persists through transformations of spatio-temporal physical particulars can and does have mass (as Kant mentions in his example).

However, Kant cannot prove a priori that it is altogether impossible for material substances to come into existence uncaused, or to be destroyed without remainder (to vanish from nature). Kant may be able to prove that we can never explain either kind of event; he may be able to prove that we can never identify such an event. However, he cannot demonstrate that no such event is possible, not even within the further strictures of transcendental idealism—despite Kant’s claims to the contrary. For this result I argued by counter-example (Westphal 2004, ¶¶ 56, 61.2; cf. Harper 2007). This point undermines any claim by Kant to prove the sempiternity of matter or substance. The most Kant’s transcendental analyses can prove is that there is sufficient conservation of material substance for us to identify and individuate enough spatio-temporal objects and events to distinguish them from ourselves and our awareness of them—an extent which cannot be specified a priori. Hall neglects my analysis of and findings on this important point.


Furthermore, the alleged omnipresent sempiternal SUBSTANCE would provide the wrong sort of unity to nature. On Hall’s account, the one omnipresent sempiternal SUBSTANCE is some one single substance which is nature, and so is a unified—numerically singular, unique—nature. Now even if nature were altogether one and the same substance—more or less Spinozistic, or a Cartesian material plenum—that would not underwrite the required “systematic unity” of our “experience” of nature (Hall, p. 141; above Section 4). This because any one single omnipresent sempiternal material substance may have such a plethora of chaotically changing characteristics that we could form no judgements about it nor about those features, even if they were to affect our forms of sensory receptivity, occasioning sensations in us. In any such world, apperceptive human experience would be impossible. The relevant “systematic unity” of nature must satisfy, not the constraint of being a numerically unitary SUBSTANCE, but rather the constraint of the transcendental affinity of the sensory manifold. In brief, any world in which we human beings can enjoy apperceptive experiences must be a world which exhibits a humanly identifiable variety and regularity of identifiable individuals exhibiting characteristics of identifiable kinds (Westphal 2004, ¶¶ 22–27). Numerical unity alone cannot do the job.

Conversely, numerical unity of SUBSTANCE is not required to do the relevant job. Instead, a causally integrated nature comprising causally interacting, perceptible, humanly identifiable particular substances undergoing some humanly identifiable motions or transformations does suffice—just as Kant says—without invoking any one, singular, omnipresent, sempiternal material SUBSTANCE.


Finally, Hall’s concept of SUBSTANCE cannot be applied to any particular(s) whatsoever—pace Hall (p. 24; see above Section 3), because it cannot be used in any determinate cognitive judgements, per Kant’s semantics of singular cognitive judgement (above, Section 8). If instead such a concept of SUBSTANCE is not to be ‘applied’ in or through cognitive judgements (nor sub-personally via the transcendental power of imagination), but rather its being instantiated is to be proven ostensively (directly) by transcendental proof, then that proof must be much more exacting and cogent than any such argument sketched by Hall.


Now perhaps Kant in his later years came to believe that he must, and could, prove stronger and much more controversial existence claims than are allowed by the published Critical philosophy, but I have argued in detail that Kant’s transcendental analyses and proofs in the Critique of Pure Reason are in several important regards much more sound, powerful and insightful than Kant recognised. When Kant discovered fundamental problems in the Critique, his views confronted philosophical divide (Westphal 2004, ¶ 59). Kant chose to raise his transcendental idealist aspirations to preserve his official ‘top down’ model, so that transcendental philosophy undergirds Critical metaphysics, which undergirds empirical physics or human morals. In taking that option, Kant’s ambitions far exceeded his philosophical results. By subjecting Kant’s Critique of Pure Reason to strictly internal critique, Hegel identified exactly how to disentangle Kant’s sound Critique of Judgement—cognitive, moral and aesthetic (Westphal 2015a, ¶¶ 8, 9, 21)—from Kant’s unwarranted transcendental idealism (Westphal 2009; 2015b, c).


These considerations afford a concise reply to a serious misunderstanding of, and a misguided objection to, my interpretation and assessment of Kant’s views expressed by Hall. Hall states:

Both Kenneth Westphal and I trace the gap in Kant’s Critical philosophy back to the Analogies of Experience. For Westphal [2004, 172], the gap consists of the fact that Kant needs to establish the metaphysical causal thesis that ‘every physical event has an external physical cause’ which requires that there be spatially individuated substances. Westphal does not believe that Kant establishes the metaphysical causal thesis since all three Analogies can be explained simply in terms of Substance.[*] In other words, Westphal takes the Substance interpretation one step further than I do by claiming it is not only necessary but also sufficient for explaining all three Analogies. (p. 46; cf. p. 80)

[*] Although Westphal believes that the Analogies require the metaphysical causal thesis, Kant only argues for this thesis explicitly in Proposition Three of the Mechanics chapter of MFNS (his Second Law of Mechanics). Westphal holds that this latter argument fails. Specifically, he argues that all changes in matter could be due to a Spinozistic or living matter (hylozoism) capable of producing its own alterations. (p. 65n.32)

The first error in Hall’s claim is that my interpretation, analysis and assessment of Kant’s views appeal to any sense or concept of SUBSTANCE. For reasons give above (Sections 9–13), I find no reason to appeal to Hall’s conception of SUBSTANCE. My point regarding Kant’s Analogies of Experience and the need for Kant to specify adequate principles for individuating individual physical substances turned only on showing that one single, sufficiently large, perceptible physical (material) substance with a variety of perceptible characteristics or features, some stable though rotating whilst others change (replace one another), instantiates and illustrates equally well the principles of causal judgement Kant identifies and justifies in the first two Analogies of Experience. A plurality of distinct physical substances is required, however, by the principle of causal judgement Kant specifies and defends in the Third Analogy. Consequently, Kant’s justification of transeunt causal interaction between spatio-temporal substances—his Critical response to Hume and to Leibniz—cannot lie in the Second Analogy (alone). Because causal judgements are discriminatory, they require conjoint use of all three causal principles Kant identifies and defends in all three Analogies of Experience, Kant in fact justifies causal judgements only with regard to interacting spatio-temporal physical substances (Westphal 2004, ¶¶ 36–38). None of this requires or involves Kant’s hint in the Third Analogy of an æther in the form of „allerwärts Materie“ in space (A213–14/B260–1), which Hall proposes to view as SUBSTANCE.

I further argued that Kant needs to justify, not the general causal principle, that each event has a sufficient cause, but what I called (on Kant’s behalf, and correctly quoted by Hall), the metaphysical causal thesis that ‘every physical event has an external physical cause’. This principle does indeed require that there be spatially (and temporally) individuated substances. However, I argued in detail that Kant does justify this specific causal principle, though by appeal to his semantics of singular cognitive reference (see above, Section 8). Kant’s success in this important regard is one of “Three Kantian Insights” identified and defended in my concluding chapter (Chap. 7, esp. ¶ 62).


Hall (p. 35n.115) claims I ascribe to Kant a “transcendental realism”, yet does not elaborate. However, the designation ‘transcendental realism’ has a specific, unambiguous sense within Kant’s nomenclature, to which Hall appealed previously. In Hall (2009:208–9), he acknowledged that my interpretation of the ‘gap’ Kant identified in his Critical system affords a “devastating” objection to his own interpretation. There (2009:210) he rejoins by ascribing to me a “transcendental realism”, which he rejects simply by appeal to Kant’s quadruple distinction between empirical and transcendental senses of the distinction between realism and idealism (A369–70; cf. A491–3/B519–21).

This rejoinder fails for two reasons. First, Kant’s quadruple distinction is not at all self-evident. Kant knows that he can justify this set of distinctions only by justifying his transcendental idealism. My objections to Kant’s transcendental idealism are strictly internal, and demonstrate—I respectfully submit—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. By refuting Kant’s arguments for transcendental idealism, I likewise remove all justification Kant provided for his quadruple distinction. No replacement justification is on offer from any quarter. Hence my analysis, interpretation and in many regards defence of Kant’s Critical philosophy and its transcendental analyses and proofs cannot be rebutted simply by citing Kant’s quadruple distinction. To do that is to ascribe to Kant a gross petitio principii, and to commit an equally crude petitio against my analysis.[4]

Second, I do not ascribe to Kant any ‘transcendental realism’! I repeatedly and deliberately designate the (more or less) commonsense realism about perceptible spatio-temporal particulars I argue Kant can and did prove transcendentally as “realism sans phrase“, precisely to warn against such misleading qualifications as ‘transcendental’ or ‘empirical’—or ‘internal’, ‘metaphysical’, ‘naïve’ or ‘indirect’—realism (Westphal 2004:1, 5, 34–5, 67, 72, 94, 126, 248, 250, 267–8, 270).


I shall not examine Hall’s views further. These initial problems show that he has not examined Kant’s texts and issues – nor the relevant secondary literature – with sufficient care and discernment. Regrettably, Hall neither fulfils his four conditions for a good interpretation (above, Section 1), nor does he notice his falling short of his stated goals. As these observations suggest, I have good reasons to have remained reticent about Kant’s late manuscripts on transcendental philosophy of nature.


It is not a welcome task to expose such weaknesses as Hall’s book exhibits. Yet in today’s academic environment on occasion it becomes obligatory. The shortcomings in Hall’s book are ever more characteristic of recent ‘scholarship’: publications which exhibit the trappings of scholarship, but without its substance or acumen, and so fail to contribute to our understanding of their chosen topics, but instead distract incautious readers from the best research scholarship has produced. These shortcoming do not merely lie with their authors: they are likewise shortcomings of their teachers, advisors and reviewers consulted by publishers for their presumed expertise.

These kinds of oversights and errors result inevitably from the accelerated working pace imposed ever more widely and forcefully upon faculty and students alike by managerially minded academic administrators,[5] who have failed to anticipate and respond constructively to financial contractions within academia which were known, predicted and publicised more than forty-five years ago by Byrnes & Tussing (1971). We can and we must do much better to preserve and augment academic integrity for the simple reason that if we scholars do not, no one else will, because no one else can. These issues about academic, scholarly and institutional integrity have ramifications far beyond the walls of the academy (Westphal 2016c): the ‘culture’ of low, simplistic or misguided expectations is destroying far more than just the life of the mind.[6]

Invited: 24 November 2014; received: 28 August 2016.


[1] See Hanna (2001), Westphal (2004; 2013) and Bird (2006).

[2] See Harper (2011) and Westphal (2013). I risk the pleonasm some may find in ‘cognitive justification’, but others speak of other forms of justification with regard to beliefs or claims, so that the phrase ‘cognitive justification’ is no longer redundant.

[3] See Harper (2011). For concise discussion of some key points in connection with Kant, see Westphal (2013).

[4] The same petitio is committed by Kannisto (2010:229n.9).

[5] See Head (2011), Thomas (2011), Watson (2012), Ginsberg (2011), Schekman (2013), Ferrini (2015), O’Neill (2015) and Scott (2015).

[6] See Berle & Means (1933), Burnham (1941), Rourke (1966) and Curren (2008). My new institutional home in İstanbul—Boğaziçi Üniversitesi—provides proper working conditions for sound teaching and research; what a joy!


Berle, A. and G. Means (1933), The Modern Corporation and Private Property (New York: Macmillan).

——— (1991), The Modern Corporation and Private Property, revised edition with new introductions by M. Weidenbaum and M. Jensen (New Brunswick, NJ: Transaction Publishers).

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——— (2006), ‘How does Kant Prove that We Perceive, and not merely Imagine, Physical Objects?’, Review of Metaphysics 59(4): 781–806.

——— (2007), ‘Consciousness & its Transcendental Conditions: Kant’s Anti-Cartesian Revolt’, in S. Heinämaa et al. (eds), Consciousness: From Perception to Reflection in the History of Philosophy (Dordrecht: Springer), pp. 223–43.

——— (2009), ‘Does Kant’s Opus Postumum Anticipate Hegel’s Absolute Idealism?’, in E.-O. Onnasch (ed.), Kants Philosophie der Natur. Ihre Entwicklung bis zum Opus postumum und Nachwirkung (Berlin and New York: de Gruyter), pp. 357–83.

——— (2013), ‘Kant’s Cognitive Semantics, Newton’s Rule Four of Natural Philosophy & Scientific Realism Today’, in Kant Yearbook 5: 127–68.

——— (2015a), ‘Kant: Vernunftkritik, Konstruktivismus und Besitzrecht’, in A. Travesonni-Gomez & J.-C. Merle (eds), Kant’s Theory of Law (Archiv für Rechts- und Sozialphilosophie, Beiheft 143), pp. 57–100.

——— (2015b) ‘Hegel’s Pragmatic Critique & Reconstruction of Kant’s System of Principles in the 1807 Phenomenology of Spirit’, in Hegel Bulletin 36(2): 159–83.

——— (2015c), ‘Hegel’s Pragmatic Critique & Reconstruction of Kant’s System of Principles in the Logic & Encyclopaedia’, Dialogue 54(2): 333–69.

——— (2016a), How Hume and Kant Reconstruct Natural Law: Justifying Strict Objectivity without Debating Moral Realism (Oxford: Clarendon Press).

——— (2016b), ‘Mind, Language & Behaviour: Kant’s Critical Cautions contra Contemporary Internalism & Causal Naturalism’, in S. Babür (ed.), Felsefede Yöntem/Method in Philosophy, special issue of Yeditepe’de Felsefe/Philosophy at Yeditepe 10 (İstanbul: Yeditepe Üniversitesi Press), pp. 102–49.

——— (2016c), ‘Back to the 3 R’s: Rights, Responsibilities & Reasoning’, SATS 17(1) [forthcoming].

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© Kenneth R. Westphal, 2016.

Kenneth Westphal is Professor of Philosophy at Boğaziçi University Istanbul, Turkey. He has published widely in Kant’s theoretical and practical philosophy, German Idealism (specifically Hegel), moral philosophy, aesthetics and epistemology. His latest book is How Hume and Kant Reconstruct Natural Law: Justifying Strict Objectivity without Debating Moral Realism (Oxford UP, 2016).