KIYOSHI CHIBA | Kants Ontologie der raumzeitlichen Wirklichkeit | Walter de Gruyter 2012
By Henny Blomme
The goal of Chiba’s book is to answer the following question: Is Kant’s ‘transcendental idealism’ ‘realism’ or ‘idealism’? (Chiba 2012:2) Chiba concludes that Kant is an anti-realist: objects do not exist independently of our cognition. Chiba’s book contains a lot of interesting and precise analysis of parts of Kant’s argument in the Critique of Pure Reason. So it should be clear that the following remarks, although they express disagreement or reservation, are in no sense meant to hold back anyone from reading Chiba’s book. The contrary is the case: although I do not agree with everything Chiba affirms and defends, I can recommend his in its detail very informative dissertation to anyone who is interested in the attempt to link Kant’s theory to the contemporary ‘realism’ debate.
My critique will concentrate on three points. First, the analysis of the question that Chiba poses will bring me to a critique of the task he has set himself. Secondly, I address Chiba’s account of things in themselves. Thirdly, I criticise his assumption of a transcendental affection through such things in themselves. I’ll end with some concluding remarks on Chiba’s undertaking.
1. The Main Question
As Chiba himself notes, at first the question “Is Kant’s ‘transcendental idealism’ ‘realism’ or ‘idealism’?” seems to be superfluous, because it would be strange if ‘transcendental idealism’ was not (at least some kind of) ‘idealism’ (Chiba 2012:2). But, as Chiba points out, some Kant-commentators do see themselves as offering a realist interpretation of Kant’s position (Chiba 2012:2). It is helpful to define the way in which the labels ‘realism’ and ‘idealism’ are commonly understood. Succinctly stated, ‘realism’ holds that the ‘objects of our cognition exist independently of us’ whereas ‘idealism’ holds that these object are “in some sense dependent on us” (Chiba 2012:2). It is striking that the given definitions of ‘common realism’ and ‘common idealism’ do not exclude the possibility of a philosophical theory having to be characterised both as realism and as idealism. Such a theory would hold that, while objects of our cognition are ‘in some sense dependent on us’, they do “exist independently of us”. The problem for Chiba’s main research question is that such a characterisation (both realism and idealism) seems to offer a good description of Kant’s position—but if that were the case it would make his question unanswerable.
In order to be able to answer his main question, Chiba thus has to transform the definitions of realism and idealism in such a way that they mutually exclude each other. For a non-ambiguous result, Chiba needs definitions that make it possible to state that Kant’s philosophical position is either “idealism and in no way realism” or “realism and in no way idealism”. A first step is to specify the formula ‘objects of our cognition’ and to talk about realism or idealism with regard to objects in space and in time (Chiba 2012:11). In light of this, Chiba then also transforms his thesis as follows: Kant’s transcendental idealism with respect to spatiotemporal objects is anti-realism, but Kant’s transcendental idealism with respect to ‘things in themselves’ is realism (Chiba 2012:14).
A second step is inspired by the discussion of the so-called analytical realism-debate in the work of Michael Dummett, and seeks to define more precisely what realism and anti-realism are. In light of Dummett’s input, Chiba then defines realism as stating that truth and falsehood of propositions about spatiotemporal objects are determined independently of our cognition of these objects, so that the question if we can verify them or whether they can possibly be verified is fully irrelevant for the truth of these propositions. Anti-realism is defined as a position that does not accept this, and considers that the truth of propositions about spatiotemporal objects is in some way dependent on their (possible or actual) verification (Chiba 2012:11).
At this point, I want to comment on the way in which Chiba presents his thesis with respect to Kant’s position. A first remark concerns the fact that Chiba summarises Kant’s position by naming it ‘transcendental idealism’. Although Chiba, in doing so, follows an already long tradition, this is not unproblematic. In order to see this, we have to get back to some early readers of Kant. Kant himself does not refer to the Critique of Pure Reason as the exposition of the philosophical position (or the system of) ‘transcendental idealism’. As we know, his critical solution involves both transcendental idealism and empirical realism, both with respect to space and time (in the Aesthetic) and with respect to spatiotemporal objects (in the Fourth Paralogism of the A-Edition).
Now, from the very moment that the Garve-Feder review of the first Critique stated that the critical solution presents a ‘system of transcendental idealism’ and amounts to some kind of Berkeleyan idealism, readers of the Critique have been under the spell of ‘transcendental idealism’, whereas Kant’s commitment to the complementing ‘empirical realism’ was kept in the dark. It would be better to speak of Kant’s critical solution, which urges us to take a twofold stance on the status of spatiotemporal objects: we have to defend both their transcendental ideality and their empirical reality.
A second remark concerns the definition of ‘idealism’. In the year following the publication of the Garve-Feder review, Kant reacted to the ‘accusation’ of idealism. In the Prolegomena, he writes:
Idealism consists in the claim that there are none other than thinking beings; the other things that we believe we perceive in intuition are only representations in thinking beings, to which in fact no object existing outside these beings corresponds. I say in opposition: There are things given to us as objects of our senses existing outside us, yet we know nothing of them as they may be in themselves, but are acquainted only with their appearances, i.e., with the representations that they produce in us because they affect our senses. […] Can this be called idealism? It is the very opposite of it. (AA 4:288–9)
The end of this passage is quite clear: Kant does not want his position to be called ‘idealism’. The reason seems to be that he uses another definition of idealism than the one Chiba proposes at the very beginning of his book under the heading ‘idealism in the common sense’. For Kant, in this passage, idealism is “the claim that there are none other than thinking beings”, not the conviction, that “objects are in some way dependent on us”. If idealism is understood in the way in which Kant understands it here, then transcendental idealism of spatiotemporal objects does not necessarily imply idealism (‘in the common sense’).
In light of this, it is no bad choice of Chiba after all, to speak of ‘anti-realism’ instead of ‘idealism’, but it would have been helpful to find a discussion of the Kantian definitions of ‘idealism’ right at the beginning of his book. It is only on page 179 of his book that Chiba discusses it and remarks that Kant’s definitions of idealism do not correspond to what he (Chiba) called (on the first page) ‘idealism in the common sense’. After having quoted another passage of the Prolegomena, where Kant states that idealism in the common sense amounts to doubting the existence of what we consider to be outer things (see AA 4:293), Chiba remarks: “This is an indication of the fact that one cannot simply project the contemporary understanding onto Kant’s conception” (Chiba 2012:179). But if this is the case (and both Chiba and I think so), then this remark comes very late.
It is indeed only in part 5 that Chiba starts to discuss the different kinds of ‘idealism’ that are to be found in Kant’s text of the Fourth Paralogism in the A-edition of the Critique of Pure Reason. Chiba’s analysis (as almost every analysis in his book) is precise: ‘dogmatic idealism’ and ‘sceptical idealism’ are specifications of ‘empirical’ or ‘material’ idealism. ‘Empirical’ or ‘material’ idealism denies or doubts the existence of outer objects: ‘dogmatic idealism’ denies their existence, whereas ‘sceptical idealism’ doubts their existence. Chiba then remarks that “sceptical and dogmatic idealism […] are neutral with regard to realism / anti-realism” (Chiba 2012:181). Again, I think that this clarification should have been made right at the start, because one of its consequences is that Kant’s empirical realism does not necessarily exclude Chiba’s anti-realism (See Chiba 2012:57–9).
We thus get the following picture: On the one hand, we find Kant writing explicitly that his transcendental idealism is no idealism in the common (received) sense. Moreover, he explicitly defends empirical realism with regard to spatiotemporal objects. On the other hand, we find Chiba defending that transcendental idealism is idealism in the common sense and that it is to be interpreted as anti-realism of spatiotemporal objects. Although there is, following Chiba, no blatant contradiction to be found here once the terms get properly defined, it is a confusing terminological situation to start with. Chiba himself remarks that, once one uses his definitions, the characterisation of a position as ‘anti-realist’ is not very informative (Chiba 2012:22).
This brings me to my next point. As we saw above, the Dummett-inspired definition of anti-realism that Chiba gives in the beginning of his book is as follows: the truth of propositions about spatiotemporal objects is dependent on the (actual or possible) verification of those propositions. During his analysis of Kant’s Critique, most of the time Chiba uses a more general definition of anti-realism, which only affirms that the existence of spatiotemporal objects is (in some way) dependent on our cognition. But later on, Chiba states that the anti-realism he defends should be taken to be compatible with the following thesis:
How spatiotemporal objects are constituted (in other words: which propositions relative to spatiotemporal objects are true and which are false) is already determined before all actual realisation of cognitions, namely through conditions which are independent from such realisation. (Chiba 2012:383)
That this thesis is incorporated into the anti-realism that Chiba takes to be Kant’s position shows in my opinion how right Kant was to speak both of (some kind of) idealism and of (some kind of) realism with regard to the existence of spatiotemporal objects. For Chiba, though, the determination in question is one that takes place on the level of things in themselves: the truth of propositions about spatiotemporal objects is determined before the verification of these propositions, because the things in themselves determine the spatiotemporal objects with regard to their matter.
In what follows, I would like to propose an alternative reading. While I do agree with the thesis that the truth of propositions about spatiotemporal objects is determined independently of their verification, I think that this determination doesn’t concern things in themselves but the empirical objects to be encountered in experience. In order to give a short sketch of my alternative reading, I will first critique Chiba’s interpretation of the thing in itself (Section 2) and then comment on his defence of transcendental affection (Section 3).
2. Things in Themselves
Chiba states the following: “Things in themselves do affect us in order to bring forth in us [in unserem Gemüt] the sensible matter for empirical cognition” (Chiba 2012:332). As a consequence, he must affirm the existence of things in themselves. In the following, I evaluate these claims. Chiba distinguishes between two main interpretations of the thing in itself: (I) It is essentially an object of thought (in this case, the possibility that things in themselves exist has to be excluded); (II) It is a thing that is defined as a something that is independent of our cognition. With regard to II, Chiba further distinguishes between (IIa): Things in themselves cannot be said to exist, but neither can we prove that they don’t exist; and (IIb): Although we cannot know anything in particular about things in themselves, we do know that they must exist (Chiba 2012:336). Chiba then argues for interpretation IIb. Although Chiba would certainly deny that such an interpretation can be coherent, I will argue for a combination of I and IIa.
In the third chapter of his book, Chiba gives an overview of the debate between defenders of the so-called two-world and two-aspect interpretations of the thing in itself. While this overview is well-written and helps to mark subtle differences between contemporary commentators, I think Chiba doesn’t sufficiently heed its most important message: there is no such thing as a two-world interpretation and a two-aspect interpretation. That is of course nothing new, but I think that Kant commentary has failed to take it as an indication that the whole debate is wrong-headed from the start. The distinction between ‘two worlds’ and ‘two aspects’ is still referred to in almost every discussion about the thing in itself as if it would entail a perfect disjunction, although it is clear that it doesn’t (see also Dennis Schulting’s excellent introduction to Schulting & Verburgt 2011).
I think that overviews of the current debate like Schulting’s and the one in Chiba’s third chapter do teach us an important thing, namely that the ‘two world’ and ‘two aspect’ distinction has had its best time: Kant scholars should acknowledge that it only adds to confusion. In my view, Kant’s theoretical philosophy does neither allow us to affirm the existence of a ‘second world’ (that is: a ‘world’ of things in themselves), nor does it allow us to state that ‘in-itself-ness’ is an ‘aspect’ of appearances without thereby generating unnecessary new problems of interpretation. In my opinion, a fruitful interpretation of the status of the thing in itself has to start with leaving aside the artificial distinction between ‘two worlds’ and ‘two aspects’ interpretations.
To be able to give a rough-and-ready sketch of the alternative reading that I want to propose, it’s good to start with a passage in Kant’s Critique that I consider to be crucial—and I think that its importance hasn’t been fully appreciated in Kant commentary. In the Amphiboly-appendix, Kant says that, from the four pairs of concepts of reflection, it is the pair “matter” and “form” that is the most important:
Matter and form. These are two concepts that ground all other reflection, so inseparably are they bound up with every use of the understanding. The former signifies the determinable in general, the latter its determination (both in the transcendental sense, since one abstracts from all differences in what is given and from the way in which that is determined). The logicians formerly called the universal the matter, but the specific difference the form. In every judgment one can call the given concepts logical matter (for judgment), their relation (by means of the copula) the form of the judgment. In every being its components (essentialia) are the matter; the way in which they they are connected in a thing, the essential form. […] The understanding, namely, demands first that something be given (at least in the concept) in order to be able to determine it in a certain way. Hence in the concept of pure understanding matter precedes form […]. (A266–7/B322–3)
Our understanding automatically takes matter to precede form. So the natural way of thinking the relation between matter and form in the transcendental sense is that matter, as the determinable in general, has to be given first, so that it can consecutively be determined by the form. This order pertains to the pure understanding in its capacity to build judgements, because it is reflected by the rules of (syllogistic) logic. For this reason, says Kant, Leibniz had to pose ‘monads’ to function as transcendental matter. A consequence thereof was that Leibniz had to think of space and time as forms that were the sensible expression of the relation between monads, that is, as mere determinations of things in themselves. So for Leibniz, in line with the basic and natural rules of pure thought, the monads (Leibnizian things in themselves) had to precede every possible determination or accident of them and thus also space and time.
Now one of Kant’s revolutionary moves consists in inversing this ‘natural order’ of our understanding. Of course he does not deny the logical order of determination, where (in the most general sense) matter precedes form, but he limits the validity of this order to the domain of the pure understanding. He states explicitly that it is not valid when we consider things given by our senses, that is, things to which corresponds an intuition. The natural order would be valid for given objects, if space and time were determinations of things in themselves. But as we know, for Kant this cannot be the case: space and time cannot be determinations of things in themselves, because then we would find ourselves in the unexplainable situation that we intuit determinations of things that are themselves not given in intuition (and from which we thus cannot affirm that they exist—the presence of an intuition being one of the conditions of the real possibility of a ‘thing’). As Kant says: “[N]either absolute nor relative determinations can be intuited prior to the existence of the things to which they [i.e., these determinations] pertain […]” (A26/B42).
The consequence of the fact that space and time are not determinations of things in themselves, but a priori intuitions that function as necessary forms of intuition, is that the natural or logical order of determination (matter preceding form) is not valid when it comes to objects of intuition: here form precedes matter. Again, Kant writes that if time and space
[…] are only sensible intuitions in which we determine all objects merely as appearances, then the form of intuition (as a subjective constitution of sensibility) precedes all matter (the sensations), thus space and time precede all appearances and all data of experience and instead first make the latter possible (A267/B323; translation amended).
When it comes to appearances (that is, the undetermined objects of sensible intuition), we have to affirm that form precedes matter. This insight is crucial for the interpretation of the status of things in themselves, because it entails that the all too natural thought that some ‘transcendental matter’ has to lie at the ground of appearances, is false. That this has been overlooked by almost all scholars who tried to give a valid interpretation of the status of things in themselves, is an indirect proof of the automatism with which we think about the relation between “determinable” and “determination”. But if we apply the natural way of thinking about this relation (that is, the order that pertains to the laws of pure understanding) to appearances, then we construct a logic of illusion [Logik des Scheins] and have fallen prey to dialectical thought.
In my opinion, notwithstanding his valuable analysis of the contemporary debate on the status of the thing in itself, Chiba is but another victim of this all too natural but dialectical conclusion that there must be some kind of ‘transcendental matter’, some kind of ‘determinable something’ that precedes the forms of intuition. But the forms of intuition are given as originary forms, that is, as determinations that precede all matter which they determine and make possible. Kant writes:
But since sensible intuition is an entirely peculiar subjective condition, which grounds all perception a priori, and the form of which is original, thus the form is given for itself […]. (A268/B323–4)
Hence, no thing in itself is needed for the possible realisation of the forms of intuition as forms of empirical objects. In other words: the empirical reality of space and time does not presuppose any transcendental reality, that is, neither the transcendental reality of space and time nor the transcendental reality of things in themselves.
As I mentioned above, regarding Chiba’s distinction between possible interpretations of the thing in itself, I would like to argue for a combination of I and IIa, because I think we can distinguish between two aspects (pun intended) of the concept ‘thing in itself’. The first aspect is grasped when the ‘thing in itself’ is considered to be the concept that is logically opposed to the concept ‘appearance’. In this sense, it is a concept of the pure understanding in its merely logical use. Because Kant teaches that it is the determination by the merely subjective forms of space and time that obliges us to regard given objects as “mere appearances”, and because we inevitably think that the determination through forms must be preceded by some ‘determinable’ transcendental matter, we automatically form the concept of a thing in itself. That is the sense of the passages that are quoted by Chiba to prove that Kant affirmed the existence of things in themselves. Consider the following examples (Chiba 2012:80):
Thus if one asks (in respect of [the conception of] a transcendental theology) […] whether there is anything different from the world which contains the ground of the [cosmic] world order and its connection according to universal laws, then the answer is: Without a doubt. For the world is a sum of appearances, and so there has to be some transcendental ground for it, i.e., a ground thinkable merely by the pure understanding. (A695–6/B723–4)
Therefore the understanding, just by the fact that it accepts appearances, also admits to the existence of things in themselves […]. (AA 4:315)
First of all, we should observe that the first example is not very well chosen by Chiba, because it is clear from the context that with ‘ground’ Kant does refer here to the ens realissimum as the deistic conception of God and not to the thing in itself. Nevertheless, we can indeed use it indirectly for the interpretation of the thing in itself, in that ‘thing in itself’ and ‘God’ are both to be classified as necessary entia rationis, that is, merely thought objects of concepts to which corresponds no (sensible) intuition: both are empty concepts without objects that can be intuited. That’s why Kant states, in the first passage quoted above, that this ground (that necessarily must be thought) is “thinkable merely by the pure understanding”.
In the second passage, we should indeed observe that Kant says that the understanding (that is, pure understanding as opposed to the understanding in its empirical use) admits to the existence of things in themselves naturally (or logically) in so far it also admits that something is merely appearance and not thing in itself (namely the spatiotemporal object). But this existence is a merely thought existence: we have no intuitional content, which is always required to admit to the existence of an object within empirical thought (that is, existence as a modal category). Following this line of thought, we end up with the thing in itself as in interpretation I.
Now, while the characterisation of the thing in itself as ens rationis (Gedankending) does imply that it is an empty concept, it does not imply that we can affirm that things in themselves do not exist. Again, as is the case with other entia rationis such as ‘God’, theoretical philosophy must leave the question about their existence undecided. When Kant writes that entia rationis, for example noumena, cannot be counted among the possibilities, he adds immediately that this doesn’t mean that they can or must be said to be impossible (A290/B347). It is merely their real possibility that must be denied. That’s why interpretation IIa is also valid. Not because the thing in itself is defined by the characteristic ‘being uncognisable’ (it is defined by being not an object of the senses, from which it follows analytically that it cannot be cognised), but because we can affirm nothing with respect to its existence: neither that it exists, nor that it does not exist.
There is nothing wrong with the conception of a thing in itself (its concept is eo ipso generated by the laws of the pure understanding), as long as we do not affirm that such a thing does indeed exist or that it appears in the Critique to secure Kant’s private ontology (Adickes 1924:16,60,93). Although we inevitably must think the thing in itself as something which precedes the forms of intuition, that is, as something that gives us the ultimate ground for the fact that spatiotemporal matter is given to us (and thus also as something that is somehow affecting us), we can state nothing about its real possibility. With respect to the existence of things in themselves, Kant teaches us to be agnostic.
3. Transcendental Affection
In the above section, I criticised Chiba for failing to see the actual independence of the forms of intuition from a given transcendental matter. That is also the reason why he thinks that we must accept a transcendental affection through things in themselves. In chapter 8, Chiba proposes the following argument for transcendental affection:
Step 1. In order to have empirical cognition, it is necessary that sensible matter is given to us (and sensible matter is indeed given to us).
Step 2. There has to be something numerically different from us that affects us, in order to bring forth the sensible matter (as impression) in us.
Step 3. That which affects us has to be something that is independent of our cognition, because something that is dependent on our cognition cannot bring forth the matter for our cognition.
Step 4. That which affects us cannot be a spatiotemporal object, because, following Kantian anti-realism, spatiotemporal objects only exist as dependent on our cognition and that which exists as dependent on our cognition cannot be the same thing as that which exists as independent of our cognition. Therefore, that which affects us must be a thing in itself […]. (Chiba 2012:351-2)
If what Kant writes about the precedence of the forms of intuition (with respect to given intuitions) is right, then Chiba’s conclusion cannot be true. The weak point in his argument is to be found in Step 4, and more precisely in the statement “spatiotemporal objects only exist as dependent on our cognition”. This statement is true when we take the object as phenomenon, but it is false when we take the object as mere appearance. Kant uses the term ‘object’ for both the undetermined object of empirical intuition that he calls appearance, and the determined object of empirical intuition that he calls phenomenon.
Now, with regard to mere appearances, we cannot state that they are dependent on our cognition. An object as appearance is merely the empirical manifold in intuition, as being still undetermined with respect to the dynamical categories and thus not necessarily an ‘objective’ object. It is not an object that depends on our cognition (because cognizing an object supposes that is has been determined with respect to all categories), but it is of course a spatiotemporal object. So, while the ‘thing’ that affects us is necessarily spatiotemporal (because, as matter given in empirical intuition it is necessarily dependent on the a priori forms of our intuition), it is at the same time independent of our cognition.
Hence, Chiba’s statement in step 4 above, that the thing “which exists as dependent on our cognition cannot be the same thing as that which exists as independent of our cognition” is false: the object as phenomenon is the same ‘thing’ as the object as appearance, but only the former is dependent on our cognition. As a consequence, I cannot agree with the formulation of Chiba’s leading thesis, namely that the fact whether spatiotemporal objects exist or do not exist independently of our cognition determines whether Kant is realist or anti-realist. Indeed, because he formulates his Kant interpretation with the jargon of analytical epistemology , Chiba fails to see that his thesis about the ‘ontological’ status of spatiotemporal objects in Kant (namely that “the existence of spatiotemporal objects is – in some way – dependent on our cognition”) is necessarily ambiguous.
When we refer to Kant’s table of categories, one should remark that Kant mentions two categories that express existence. The first is the category of reality (under the title ‘quality’), the second is the category of actuality (under the title ‘modality’). Mere appearances (undetermined objects of empirical intuition) do exist independently of our cognition because they are real, which means that there is a corresponding sensation, through which they are given as intensive magnitudes in perception. But they do not exist in the sense that they are modally determined as actual —that is, objective—objects, which means that they are not determined with respect to the relation between our faculty of cognition and the object as an object of our empirical cognition.
Chiba’s book shows how tricky it is to use current distinctions and discussions in the interpretation of Kant’s thought. While these discussions (e.g. the realism debate) are interesting enough, I don’t see how anyone could easily grasp Kant’s multi-layered theory of the object of possible experience with the terminological distinctions that are currently used in these debates. Of course, every attempt to show in which sense Kant’s thought is still topical is laudable in itself, but I believe that the central problem one faces in relating Kant to current debates or vice versa is that Kant’s distinctions are not always dualistic, whereas most definitions in current analytical epistemology are constructed in such a way that they should be (in order to arrive at biconditionals).
The jargon of analytical epistemology thus is basically built on disjunctive propositions. These disjunctions are meant to be exclusive but I believe that most of them reveal to be inadequate once one wants to employ them in interpreting Kant. With respect to Kant’s theoretical philosophy, the disjunction that Chiba uses (“the existence of objects is independent from our cognition or the existence of objects is dependent on our cognition”) is not exclusive as long as it is not specified what is meant with object and what is meant with existence. But if Chiba would specify in which Kantian sense he wants the terms ‘existence’ and ‘object’ to be understood, I surmise that it wouldn’t appear to be very relevant anymore to want to decide whether Kant was a realist or an idealist, because then one would always end up with the interpretation of but ‘one aspect’ of his theory.
Adickes, E. (1924), Kant und das Ding an sich (Berlin: Pan).
Blomme, H. (2014), Kant et la matière de l’espace. Le problème d’une fondation transcendantale de l’expérience extérieure (Hildesheim/New York : Olms).
Chiba, K. (2012), Kants Ontologie der raumzeitlichen Wirklichkeit. Versuch einer anti-realistischen Interpretation der Kritik der reinen Vernunft (Berlin/New York: de Gruyter).
Schulting, D. & J. Verburgt (eds) (2011), Kant’s Idealism: New Interpretations of a Controversial Doctrine(Dordrecht: Springer).
 I develop this thesis in detail in Sections 1.6 and 2.4-2.6 of my book Kant et la matière de l’espace. Le problème d’une fondation transcendantale de l’expérience extérieure (Blomme 2014:125–34;162–76). For those who don’t read French, I am currently working on an English version.
© 2013, Henny Blomme
Henny Blomme is a Research Fellow at the Centre for Classical German Philosophy of the Ruhr-Universität Bochum (Germany) and a specialist of modern philosophy. Among other articles and contributions to books, he recently published the article ‘The Completeness of Kant’s Metaphysical Exposition of Space‘ in Kant-Studien. His monograph Kant et la matière de l’espace. Le problème d’une fondation transcendantale de l’expérience extérieure is forthcoming in 2014 from Georg Olms Verlag.