OMRI BOEHM | Kant’s Critique of Spinoza | Oxford University Press 2014


By Omri Boehm 

I thank Sebastian Gardner and Nick Stang for taking the time to offer comments on and criticisms of my Kant’s Critique of Spinoza. Ideally, I would have been able to respond to their comments concurrently, addressing separate topics rather than reviewers. However, given the differences between the reviews’ structure and content, it would be difficult to do so effectively. In the following, therefore, I provide a brief context of the book’s main thesis and trajectory, before proceeding to address some of Gardner’s and Stang’s comments, in that order.


It has been for a long time a common practice among Kant interpreters to assume that Spinoza’s philosophy was basically ignored by the Critical philosopher. The Critique of Pure Reason has been interpreted and studied alongside texts and challenges from Hume’s scepticism and Leibnizian metaphysics—or Descartes’ or Berkeley’s idealism, and many others—but Spinoza’s philosophy remained virtually ignored. The few more recent scholars who have been willing to consider Spinoza’s relevance to Kant commonly turned to the Pantheismusstreit (1785) as the starting point of Kant’s engagement with Spinozism—i.e. after the revolutionary arguments of the First Critique (1781) had been presented.[1]

In Kant’s Critique of Spinoza, I hoped to show that this reflects an oversight that ought to be corrected. In several bold remarks, made admittedly after the break of the Streit, Kant writes: “Spinozism is the true conclusion of dogmatic metaphysics” (Refl. 6050, AA 18:436); or—the following text would be more familiar—

if this ideality of time and space is not adopted, nothing remains but Spinozism, in which space and time are essential determinations of the original being itself, while the things dependent upon it (ourselves, therefore, included) are […] merely accidents inhering in it. (KpV, AA 5:101–2)[2]

I argue in the book that Kant is not only genuinely committed to these bold-though-brief claims—more on his commitment below—but that he holds the same position already when writing (the first edition of) the First Critique. If this is so, Kant did not, as so often assumed, discover Spinoza with Jacobi’s aid or through the Pantheismusstreit. Rather, he developed the Critical turn in conscious dialogue with Spinoza’s challenge. Arguably, he was also motivated by Spinoza’s challenge: not exclusively, of course—another word on this, too, shortly—but crucially. Kant’s Critique of Spinoza elaborates this no doubt controversial thesis, and attempts a (beginning of a) defence of Kant’s position vis-à-vis Spinoza.

Chapter 1 provides an interpretation of Kant’s pre-Critical One Possible Basis (1763), drawing on the Principle of Sufficient Reason (henceforth also: PSR), arguing that Kant’s well-known ‘possibility proof’ commits him to Spinozist monism. I also suggest that Kant was back then already aware of this commitment.

Chapter 2 takes up the First Antinomy (concerning the world’s ‘age and size’), arguing that the Antithesis’s conception of the world as infinite in space and uncreated in time reflects a Spinozist position—not a Leibnizian position, as is often assumed. (Leibniz asserts that the world is indefinite, not infinite, reserving infinity exclusively to God. Spinoza, who identifies God and world, holds that the world is infinite and uncreated.)

Chapter 3 continues along these lines to the Third Antinomy. Here too I argue that the Antithesis position—rejecting freedom by an argument from PSR—doesn’t represent a Leibnizian position, as is often assumed, but Spinozist necessitarianism. (Leibniz doesn’t offer an argument from the PSR against freedom—quite the contrary, he argues from the PSR for freedom. It is Spinoza who offers such an argument.)

As I point out, Spinoza’s metaphysics is, in fact, capable of challenging Kant’s argument in the antinomies. For whereas the Antinomies crucially depend on the claim that it is impossible to conceive of an infinite whole by collecting infinitely many finite parts, Spinoza’s cosmology views the whole as prior to its parts—not as constructed from them.

In Chapter 4, this challenge is addressed, tackling the legitimacy of Spinoza’s reliance on a notion of the totum analyticum. Previous chapters had argued that the reliance on a pre-given infinite and complete whole is illegitimate unless this whole can be adequately conceived (by Spinoza’s understanding of the term ‘adequate’). Spinoza’s most promising (and necessary) notion for such an adequate conception is that of the causa sui (necessarily, because if causa sui cannot be adequately conceived, nothing can be.) But the adequacy of that notion, I argue, stands or falls with the traditional ontological argument. If existence is not a first order predicate—in the book I defend the claim that it isn’t, but Kant’s argument here I believe is seriously lacking—then causa sui turns out to be an illusory notion—the notion of self-causation becomes the notion of no causation at all. Self-explanation, if existence is not a predicate, turns out to be a brute fact—Spinoza’s metaphysical challenge to Kant’s Dialectic falls apart.

On the other hand, if causa sui can be adequately conceived, Spinoza can probably answer the challenge presented to his metaphysics by the Antinomies.

Chapter 5 provides, from the book’s novel perspective on Kant’s relation to Spinoza, a brief historical retelling of the Pantheismusstreit. The Streit represents, I argue, not the moment in which Kant discovered Spinoza, but the moment in which the dialogue with Spinozism—which previously was left in the Critique’s background—moved to the fore. Jonathan Israel has shown that the phenomenon is familiar for other key Enlightenment thinkers. On this I agree with Israel, extending his case deep into the working of Kant’s Critical philosophy.[3]


Early in Sebastian Gardner’s acute and generous comments—which among other things involve a powerful alternative reading of Kant’s Beweisgrund—he raises a general worry, one that had been raised by others before. I now think that I should have addressed it more clearly in the book:

[O]ne may have doubts about the extent to which Boehm allows Spinoza to dominate the narrative of Kant. Is it necessary to allow as much as Boehm suggests to rest squarely on the motive of resisting Spinozism? […] [W]e do not lose anything, as far as I can see, by viewing Kant as engaged in a complex multi-sided manoeuvre, whereby the deficiencies of several philosophical positions are resolved at a single stroke—the greater the number of early modern philosophers whose difficulties can be exposed as deriving from their tacit commitment to transcendental realism, the stronger the case for transcendental idealism. Reading the Critique of Pure Reason as a critique of Spinoza should not lead us to forget that it is also and equally a critique of Hume and Leibniz, among others.

As Gardner points out, Anthony Bruno, who had reviewed the book in NDPR, already raised a similar worry, insisting on the obvious point that Kant “might respond as much to Hume as to Spinoza”—most significantly for our purposes when addressing the PSR.

There are two different answers to this question. And, despite the tension between them, I’m going to suggest both.

First, I certainly agree with what no one can deny: Kant’s philosophy is elaborated as a “multi-sided manoeuvre”. We would not lose anything if we see him as engaging a whole range of philosophers, philosophies and philosophical problems that can’t be reduced to his occupation with Spinoza. If the book gave a different impression—apparently, it did—then this was due to my struggle to convince readers, against a long tradition of interpretation, that Spinoza and Spinozism must be brought to the heart of Kant’s encounter with metaphysics. Spinoza dominates the story because I wanted to show how important his challenge is for Kant, not because I think that Hume, Leibniz, Descartes, Berkeley and a host of other philosophers aren’t.

Moreover, as Gardner I think implies we actually do lose quite much if we do not recognise Kant’s “multi-sided manoeuvre”. Transcendental idealism is all the more interesting, fruitful and powerful if it can show the way in which the commitment to transcendental realism has led astray a diversity of philosophical positions.

Nevertheless—without denying the obvious ways in which a ‘liberal’ consideration of a plurality of philosophers is the only accurate way to read Kant—I do also think that something goes lost if we overlook a pressure coming from a less liberal perspective. The illiberal trend would be familiar to most from Jacobi’s slogan, adopted from Lessing’s assertion in their infamous Wolfenbüttel discussion, that “there is no philosophy other than Spinoza’s”. Lessing and Jacobi clearly agree with Bertrand Russell’s later comment, according to which “Leibniz fell into Spinozism whenever he allowed himself to be logical”. They insist that only a Blendwerk separates Leibniz’s philosophy from Spinozism.

Kant, or so I argue in the book, is committed to the same proposition. Some of the relevant quotes were already brought above. He claims: “Spinozism is the true conclusion of dogmatic metaphysics.” Or, “those who take space as a thing in itself or as a property of things are forced to be Spinozists, i.e., they take the world as the embodiment of determinations from one necessary substance” (V-Met-K3E/Arnoldt, AA 29:132). In the Second Critique Kant writes:

[I]f this ideality of time and space is not adopted, nothing remains but Spinozism, in which space and time are essential determinations of the original being itself, while the things dependent upon it (ourselves, therefore, included) are […] merely accidents inhering in it. (KpV, AA 5:101–2)

And, in the paragraph that preceded this claim, Kant had explained that the Leibnizian aspiration to view space and time as “essential determinations” without ascribing them to “the original being” is arbitrary and illegitimate. In fact, he writes that this Leibnizian version of transcendental realism is insincere.[4]

Needless to say, this boldly illiberal position concerning transcendental realism is not just offensive, but extremely controversial. One might wonder whether Kant was ever seriously committed to it—i.e. whether he ever argued for it. I believe that Kant was, and that an argument for this commitment can be found in the Observation on the Thesis of the Fourth Antinomy. The book reconstructs this argument (p. 125–6), and I briefly reconstruct the argument in reply to Stang below.

It is perhaps worthy of notice (the book mentions this only briefly in a footnote) that Kant reiterates the claim that Leibnizians cannot avoid Spinozism also in a comment that he adds to the B-edition of the Critique’s “General Remarks” on the Transcendental Aesthetic. There, Kant writes:

In natural theology, where once conceives of an object that is not only not an object of intuition for us but cannot even be an object of sensible intuition for itself, one is careful to remove the conditions of time and space from all of its intuition […]. But with what right can one do this if one has antecedently made both of these into forms of things in themselves, and indeed ones that, as a priori conditions of the existence of things, would remain even if one removed the things themselves?—for as conditions of all existence in general they would also have to be conditions of the existence of God. If one will not make them into objective forms of all things, then no alternative remains but to make them into subjective forms of our kind of outer as well as inner intuition, which is called sensible because it is not original, i.e., through which the existence of the object of intuition is itself given […]. (B71–2)

As I understand Kant, his rhetorical question by “what right” can a transcendental realist “remove time and space” as “conditions of the existence of God” repeats the same claim—made in the Second Critique while mentioning Spinoza and Leibnizian insincerity—that he cannot “see” how transcendental realists “justify themselves” in viewing space and time as properties of “created beings” but not of the “original being” itself (KpV, AA 5:102–3). Thus at least insofar as rationalist Leibnizian alternatives to Spinozism are concerned, there is at least some value in recognising the merits of a less liberal perspective. When Kant is engaging transcendental realism, the position he engages—in some sense—needs to be Spinozist.

A somewhat similar (but certainly not identical) point can be made also concerning the impact of Hume’s empiricist challenge. I cannot develop this point sufficiently here, but the issue is worth at least a brief promissory comment.

Hume’s argument against causality depends on a strong understanding of causality, according to which causation between two objects requires a conceptual connection: if one object (or event) causes another, then not only are they necessarily connected; the necessity itself is also conceptual such that causality amounts to  “a demonstration, and wou’d imply the absolute impossibility for the one object not to follow, or to be conceived not to follow upon the other” (Treatise[5] Drawing on this conception, Hume proceeds to “deconstruct” causality by claiming that there cannot be such conceptually necessary connections between distinct objects. Specifically, given that causes and effects are distinct (or so Hume, perhaps, assumes), and given that all distinct objects can be separately conceived—given, lastly, that conceivability for Hume implies possibility—no conception of one object could show “the absolute impossibility for the one object not to follow […] upon the other”.

The assumption that Hume is making here—again, if he is making this assumption—is that there are distinct things, specifically that causes and effects are distinct. But then while this argument indeed presents a serious challenge to most philosophers, it leaves Spinoza’s position untouched: given Spinoza’s monism, causes and effects just aren’t distinct. This is a crucial point, of which Hume seems to be well aware. In the Treatise, he characterises Spinoza’s monism thus:

[W]hatever we discover externally by sensation; whatever we feel internally by reflection; all these are nothing but modifications of that one, simple, and necessarily existent being, and are not possest of any separate or distinct existence. (T

Given this situation, Hume can only dismiss Spinozism as a “hideous hypothesis” (T But he did not offer an argument against his monism, and not against his conception of causality.

All this is to point out that also when we’re dealing with Hume’s challenge—which to be sure agitated Kant as Hume’s challenge, not Spinoza’s—we discover the relevance of Kant’s claim that transcendental realists are “forced to be Spinozists”. His claim is that if transcendental idealism is not adopted, “only Spinozism remains”.[6]

For these reasons, while I obviously agree that we “lose something” if we reject the accurate ‘liberal’ approach,  according to which the Critique of Pure Reason engages transcendental realism by addressing a fruitful variety of different philosophies and philosophers, I also believe that we lose something if we overlook a less liberal pressure. According to the latter, when Kant takes transcendental realism to task, and encounters obvious transcendental realist interlocutors such as Leibniz or Hume, the discussion is one way or another fraught with the realisation that transcendental realists are “forced to be Spinozists”.

Gardner’s suggests next that, by contrast to my assumptions, Kant’s One Possible Basis argument for God’s existence does not draw on the PSR, but on an alternative insight (another word on that insight below). According to Gardner—who by this claim consciously challenges not just my own interpretation, but a much broader trend—Kant had in fact expressed misgivings about the PSR already in the New Elucidation. In the Beweisgrund, he “gives no sign of relying” on it. Indeed, for Gardner, the thrilling novelty (literally taking Jacobi’s breath away) of Kant’s argument lies in turning its back on an old principle such as the PSR, and introducing an idea that is “genuinely distinguished from early modern rationalism with regard to its method”. According to this idea, “we cannot think away the situation of thinking’s being possible.” Or as he puts it elsewhere:

Kant’s claim, as I understand it, is that thinking manifests immediately the reality of possibility in a way similar to that in which, according to Descartes, it manifests the reality of a thinker, that is, without any inference […]. If the reality of possibility is testified directly by our thinking, then no principle of thought, such as the PSR, is needed […].

(To be on the safe side, this paragraph appears in a specific context, where Gardner argues that this principle sustains Kant’s claim that, necessarily, something is possible. But if I understand him correctly, he means the same principle to systematically replace my [and others’] tendency to fall back on the PSR in reconstructing Kant’s argument.)

Since I find the suggestion ingenious and illuminating—and since, as Gardner points out, it does not undermine the book’s thesis, nor even the possibility that the One Possible Basis at least in some sense invites Spinozism—I do not wish to argue here against it. But I do wish to briefly register a remark and a question. First, it seems to me that the evidence for Kant’s reliance on the PSR in the Beweisgrund is stronger than Gardner allows. For one thing, despite Kant’s “misgivings about Wolff’s use of the PSR” (Gardner) in the New Elucidation, the essay’s fifth proposition actually provides a definition, and a purported proof, of an unrestricted version of it, according to which “nothing is true without a determining ground” (PND, AA 1:393). Moreover, it seems that in the Beweisgrund Kant is still willing to “subscribe” to it (BDG, AA 2:158).[7]

Gardner’s criticism of my PSR-based reconstruction of Kant’s argument also proceeds by claiming that

[i]f the PSR is stated simply in the standard form of the requirement that nothing be (allowed to be thought to be) the case without (its being thought that there is) sufficient reason for its being the case, i.e., simply as answering ‘why?’ questions, then it does not of itself tell us what ontological status, if any, is to be assigned to whatever it is that counts as sufficient reason.

On this understanding of the PSR’s “standard form”, I do differ from Gardner. The PSR, as I understand it in the book—the same I think goes for Kant’s “Supreme Principle of Pure Reason” in the Critique, which I understand as his formulation of the PSR he would be attacking—states that for every thing, event or state of affairs there is a sufficient explanation. If the ultimate reasons for a thing’s existence do not actually exist, they cannot function as an ultimate explanation. For the why-question as for the reason for these reasons’ existence would still be lacking. This threatens to generate an indefinite regress, which would undermine the notion of sufficient explanation. Therefore, I do believe that once the PSR is stated in its unrestricted form we get an ontological status assigned to “whatever it is that counts as sufficient explanation”. In my view, this can be plausibly read as the basic idea standing behind Kant’s insight that existence must be prior to possibility.[8]

Concerning Gardner’s suggestion that Kant’s argument assumes the idea that “the reality of possibility is testified directly by our thinking”, I have one (so to speak) honest question about it. Depending on the type of answer one would give, it could perhaps either challenge Gardner’s alternative approach or support it.

As Gardner remarks in the paragraph quoted above, Kant’s idea that thinking manifests possibility immediately, is analogous to the Cartesian idea that thinking immediately “manifests the reality of a thinker […] without any inference”. It would be intriguing to see Gardner elaborate his position in relation to the contrast, stressed by James Conant (2003), between the Cartesian and the Kantian verities of scepticism. According to Conant, whereas Cartesian scepticism assumes the possibility of thought and questions the actuality of knowledge, Kantian scepticism questions thought’s very possibility. A Cartesian sceptic asks, “How do I know that this thought is true”, or “How do I know that this interpretation is correct?” A Kantian sceptic asks, by contrast, “How can I so much as think?” or “How can there be so much as meaning at all?”. The Kantian sceptic thus asks a question not merely about the possibility of knowledge, but about the possibility of experience, understood as a worry about mindedness as such; it is the possibility that thought itself is even “less than a dream” (A112).

Since the Kantian sceptic questions the possibility of thinking itself, her state of mind—if it can be called that—isn’t properly stated doubt, but utter despair. To the extent that doubt is understood as a mode of thinking, it isn’t clear that this state of mind, properly understood, is possible at all. What gets questioned is the very capacity to frame the question. Conant therefore calls this state of mind not doubt, but “a boggling of the mind”:

[H]is mind boggles. Such boggling of the mind, in the face of a looming conclusion that can neither be approached nor avoided—neither fully comprehended nor simply dismissed on the grounds of its incomprehensibility—is the mark of entanglement in a variant of the Kantian problematic. (Conant 2003:112)

The violence with which here, in what Kant calls scepticism, reason turns against itself is a violence of the most extreme possible sort. What reason questions is itself. Our faculty for rational thought arrives at the point where it asks itself (not just how this or that cognitive capacity is possible, but) how it itself is possible, questioning the possibility of the exercise of the very capacity exercised in the framing of such question. (Conant 2003:114)

The experience of one’s mind boggling that Conant is speaking of here, as far as I can see, confronts us precisely with the opposite of Gardner’s suggestion. From this perspective, at least, Kant’s deep insight is that thinking does not, as perhaps it did for Descartes, “immediately manifest the reality of possibility”.[9]

In Gardner’s reconstruction of Schelling’s dialectical return to the pre-Critical Kant, he writes:

If I am to think—and I do think!—then there must be possibility, and in order for there to be possibility, there must be some being which pre-dates thought and possibility, and hence which also pre-dates the PSR.

As far as I can see, this is just the insight, or assertion, in relation to which the Kantian variety of scepticism stands with a boggle.

As I said above, I can think of different ways in which one could reply. I’m not sure how I would. But the answer one will accept here will also have everything to do with one’s stance on Schelling’s “movement forward” from Kant by returning to the old “idea” that Kant “had glimpsed but left behind”.


Nick Stang’s sixty-page review proceeds, after a brief introduction, by methodically going through each of the book’s parts—from the Preface to Chapter 5 (excluding the Introduction). He correctly points out that the Preface contains a “reawakening” of the Pantheismusstreit, although he misrepresents the book’s aim and scope when he implies that such “reawakening” is presented as the book’s main scholarly starting point, and on that basis proceeds to undermine its motivation.

I suggest in the Preface—in consciously broad brushes that seemed appropriate for a book with a Preface and an Introduction (another word on the latter below)—that the Pantheismusstreit’s challenge still presses us today. For a rational account of nature that is consistent with a satisfying conception of value is, I believe, missing. In order to give an account of anything (and hence also of value, or of normative thinking) it is necessary to explain it in relation to something—an anchor either in the world or outside it (Stang dislikes my use of the word ‘anchor’). Spinoza’s form of rationalist naturalism, however, to the extent that it isn’t undermined by Kant’s critique of metaphysics, undercuts both alternatives. First, it (obviously) renders futile the attempt to account for value in relation to anything outside the world, or outside of nature. But, given Spinoza’s attack on teleology, his metaphysics also renders futile any attempt to rationally choose an anchor of value within the world that isn’t as good (and hence arbitrary) as any other.

Furthermore, given Spinoza’s conception of nature, and his attack on teleology, I can hardly refer to my (or another’s) capacity to set ends as a ground of ethics, because this capacity to set ends (what some Spinoza interpreters today call ‘goal directed’ action) is in fact the mark of inadequate ideas (another word on this below). Thus to the extent that the ethics of Spinoza’s Ethics does offer (let’s call it) redemption, it does so by overcoming the tendency to normative thinking. Spinoza is a greater ironist than Nietzsche: the Ethics could have been called just as well “Beyond Good and Evil”. As I point out in the book, I believe that Spinoza thinks of this ethics—probably in continuity with (his understanding of) Maimonides—along the lines with which God answers Job from the tempest. God basically answers Job’s cry for justice with a metaphysical tautology: I am that I am. If you demand justice, you didn’t get it. That is the nihilism or fatalism that, with Jacobi, I attribute to Spinoza. And that is the sketch of the challenge with which the book begins: given this challenge—coupled with Kant’s claim that if his own philosophy is rejected “only Spinozism remains”—Kant’s hope to ground ethics in our capacity to set ends depends on a successful destruction of Spinoza’s metaphysics.

Stang complains that

[t]he significant point to notice is that there is no real argument here. What does it mean for value to be “anchored”? Why must value be “anchored” in the world? And assuming that value is “anchored”, why does the denial of teleology entail that its anchor is arbitrary? Why can’t value be necessarily anchored in whatever anchors it?

I am personally not convinced that the English word ‘ground’, in the very broad sense required by the brief Preface, would have conveyed a deeper metaphysical truth than the word ‘anchor’. I also doubt that my discussion here would have gained much rigour if it had started by pointing out that in order to give a philosophical account of anything, it is necessary to explain it in relation to something—some anchor. (Some philosophers have anchored it in nature, others in reason, some in God. Others gave up.) Contrary to Stang’s suggestion in the passage, I did not claim that value has to be anchored “in the world”; I quite obviously do claim, however, that it has to be anchored in the world if an account of value is to be given at all and Spinozist naturalism is true. Concerning Stang’s next question, the reason for which lack of teleology undermines a worldly anchor was pointed out above. If teleological explanations of nature are excluded, any choice of a natural anchor would be as good as any other. More specifically, ascribing value to a thing because of its nature would be arbitrary, as would be ascribing it value due to anything that isn’t its nature.

Stang’s following question is, “why can’t value be anchored necessarily in whatever anchors it?”. I’m not completely sure that I follow the question. I don’t think that my view is much challenged by the fact that I didn’t explain why value can’t be anchored in “whatever”. Presumably, also necessity can, according to some, be brute, hence one could ask why value cannot be “necessarily anchored in whatever anchors it”. I do not think that such necessary anchoring in whatever would provide an account of value that would satisfy a rational thinker. It is possible that Stang’s next sentence is supposed to flesh out the notion of necessary grounding in whatever:

Contrary to Boehm’s suggestion […] the blindness of nature does not entail that its effects are “accidental”. Spinoza after all thinks that nature is “blind” in the relevant sense (does not act for purposes) but that everything that happens is necessary.

If this sentence was supposed to explain the notion of necessary anchoring in whatever, then I’m not completely sure that I see how it would do so. Either way, this sentence seems to me to misunderstand the (relevant sense of the) concept ‘accidental’. A metaphysics in which both nature itself and all its effects exist by blind necessity does entail that all effects are accidental. For ‘accidental’ here need not mean contingent: it means that nothing, even if it exists necessarily, exists for a reason. All effects (even if necessary) are accidental because even if there is a reason to the existence of this or that effect—this metaphysics after all is an expression of the PSR—then the term ‘reason’ assumed in this sentence doesn’t carry the normative significance that the term carries for Leibnizian, Kantian or Hegelian philosophers.

Referring to my quote from the Third Critique in which Kant says that Spinoza would have to “give up” morality as “impossible” (KU, AA 5:453) Stang elaborates on the familiar point that, for Kant, morality will remain just as “binding” even if God doesn’t exist. Spinozists, accordingly, have to give up “not the validity of the moral law”, but the possibility of achieving the “highest good”:

Spinoza and other deniers of natural teleology are forced, according to Kant, into a conflict in practical reason: they are rationally obliged to set an end (the highest good) but they also believe this end is impossible. They must give up, not the validity of the moral law, but the highest end morality sets us (the highest good).

However, I never denied the obvious fact that, for Kant, the moral law—if it can be shown to be a categorical imperative—is binding whether one believes in God or not. What I do say—and Kant, with a nod to the Pantheismusstreit, seems to be thinking the same—is that insofar as Spinozist metaphysics remains standing, this (the claim that the moral law is a categorical imperative) cannot be shown. If transcendental realism, which Kant thinks entails Spinozism, isn’t destroyed, the moral law in fact is not a categorical imperative. Here is a paragraph that Kant added to the B-Preface of the First Critique—as the Pantheismusstreit is in full swing—and which makes the point particularly clear:

If we grant that morality necessarily presupposes freedom (in the strictest sense) as a property of our will; if, that is to say, we grant that it yields practical principles—original principles, proper to our reason—as a priori data of reason, and that this would be absolutely impossible save on the assumption of freedom; and if at the same time we grant that speculative reason has proved that such freedom does not allow of being thought, then the former supposition—that made on behalf of morality—would have to give way to this other contention, the opposite of which involves a palpable contradiction. For since it is only on the assumption of freedom that the negation of morality contains any contradiction, freedom and with it morality, would have to yield to the mechanism of nature. (Bxxviii-Bxxix; trans. Kemp Smith, emphasis added)

Kant also writes in the same B-Preface that because his Critical philosophy “removes an obstacle which stands in the way of the employment of practical reason, nay threatens to destroy it, it has in reality a positive and very important sense” (Bxxv). The confrontation with Spinoza—in Chapter 5 of my book I try to show that this comment is a direct reference to the Streit—does not just defend the employment of practical reason, but its very possibility. This is what I mean when I say in the Preface that, for lack of a Kantian answer to Spinoza, the moral law would be given up as “meaningless”.

Stang concludes this part of the review by writing:

In fairness to Boehm, it is standard practice to begin a book with some dramatic claims, to get the reader’s attention. Further, all of these issues are apparently going to be dealt with in greater detail in a future book. But its effect on this reader was to make me question the author’s grasp of the issues.

Since this paragraph uses the term ‘fair’ only sardonically, it isn’t surprising that it isn’t. The Preface in fact was a prelude, presenting a general problem in large terms: the book moves on from the Preface to an introduction, ignored by Stang, which is written in a different style from the Preface, and which presents the book’s scholarly ambitions in a different light. There, the discussion begins with a brief discussions of the historical reasons for which Spinoza has been ignored when reading the Critique; continues by arguing against these reasons; enumerates some positive textual and philosophical reasons for why Spinoza should be taken into account, and states the book’s scholarly thesis, namely, “one will have to consider whether in attacking transcendental realism, Kant had Spinoza clearly in mind. I will argue that he did”.

This ambition is somewhat “dramatic” (I would like to think), and should “get the reader’s attention”. But contrary to the assertions made in the Preface, the book certainly does elaborate at length those very controversial claims by (no doubt controversial) lengthy discussions. To ignore this difference between the Preface and the Introduction while stating “in fairness” that it’s a “standard practise to begin a book with some dramatic claims”, and then to doubt my “grasp of the issues”, is—to be as charitable as I can—less than charitable.

Stang addresses next my characterisation of Spinozism. He enumerates Spinozism by possible doctrines, SP1–7:

SP1. There is only one substance (God); everything else is a mode of this one substance. (Ip14–15).

SP2. God is extended. (Id6, Ip15s)

SP3. Every finite being (mode) follows necessarily from a ‘preceding’ one. (Ip28)

SP4. Everything is a necessary consequence of the existence of a necessary being. (Ip29)

SP5. There is no incompatibilist free will, either in God or in finite beings. (Ip17s, Ip29)

SP6. Nothing happens for a purpose; there is no teleology in nature. (I, Appendix)

SP7. God does not ‘create’ the world, does not act for purposes, etc. (I, Appendix)

According to Stang, “Boehm frequently identifies one of these doctrines as a target of Kantian criticism and then describes Kant as criticising the ‘Spinozistic’ position”. The problem, he argues, is that “while all of these doctrines are upheld by Spinoza, some of them are upheld by non-Spinozists as well”, e.g. by Leibniz and Wolff, who hold (the argument goes) SP3–SP5. Stang then argues that I “barely discuss” in my argumentation “SP1” and focus “most of [my] attention” on SP2–5; at least SP3–5, as he says, are also held by Leibniz and Wolff.

These claims are never substantiated by serious references (the one reference I found is discussed below), and, as far as I can see, they are false. When a position is identified in the book as Spinozist, this is done almost exclusively on the basis of what Stang calls “SP1” (namely substance monism). The first chapter, for example, argues that Kant’s possibility proof, provided in the One Possible Basis, commits him to Spinozism because it commits him to substance monism. (This claim is very controversial in its own right, of course, but for our purpose here this is beside the point.)

The second chapter, on the First Antinomy, identifies the antithesis position as Spinozist by (a) the notion of the world’s infinity rather than indefinite nature, which requires, I argue, the identification of the world with God; and relatedly (b) through Kant’s claim that the antithesis reflects a view in which the unconditioned is “conceived” of as consisting in an entire cosmological “series in which all the members without exception are conditioned and only the totality of them is absolutely unconditioned”—i.e. through substance monism (“SP1”). Naturally, in this chapter reference is also made to what Stang calls “SP2”, i.e. the view that God is extended. But it is hardly controversial that this, too, is a Spinozist thesis that Leibniz or Wolff would deny.

The third chapter, on the Third Antinomy, indeed involves discussions that could seem relevant to Stang’s SP4, but it does so precisely by arguing (see below) the distinction between Leibnizian determinism and Spinozist necessitarianism. Stang’s SP4 is presented as neutral to that distinction—stating merely that “everything is a necessary consequence of the existence of a necessary being”—but this is misleading, because Spinoza’s position isn’t neutral to that distinction. Furthermore, also this chapter identifies the antithesis as Spinozist by reference to Stang’s SP1 (substance monism), because it ultimately falls back on Kant’s claim that the antithesis is conceived as an unconditioned “consisting of the entire series in which all the members without exception are conditioned and only the totality of them is absolutely unconditioned” (A417/B445).

Contrary to Stang’s claim that the book “barely discusses” monism, it actually discusses different conceptions of it, most significantly through the question whether Spinozist monism can be one in which the unconditioned is composed of its parts, or prior to them. As far as I can see, that is the central relevant question about monism in this context, because it tackles directly Kant’s argument in the Antinomies (to wit: that it is impossible to conceive the unconditioned by completing “an infinite successive synthesis”). As I show—Stang actually refers to this discussion—it was a common but very misleading practice in eighteenth century philosophy to dismiss Spinoza’s monism (!) by claiming that he constructs an infinite unconditioned whole by collecting infinitely many finite parts. Some scholars have argued that because Kant does not commit this mistake—he conceives his (arguably) monistic conceptions such as the All of reality as prior to its parts—his view isn’t Spinozist. I have argued that this is misleading—the fact that Kant doesn’t buy into the prevalent clichés of the time about Spinoza’s monism but construes a conception that is rather adequate to it is a good indication that he understands the view. Here is a paragraph from Kant, quoted in the book, that shows his sensitivity to the misconceptions regarding Spinoza’s monism quite well:

Pantheism still has Spinozism as a species under it […]. I can say, everything is God, and this is the system of Spinozism, or I can say the ‘All’ is God, like Xenophanes said, and this is pantheism. Pantheism is either one of inherence, and this is Spinozism, or one of aggregates […]. Spinoza says: the world inheres in God as accident, and so worldly substances are his effects, but only one substance exists in itself […]. In Spinozism, God is the ground [Urgrund] of everything that is in the world. In pantheism he is an aggregate of everything that is in the world. (V-Met-K2/Heinze, AA 28:794-5; trans. mine)

To propose that the book does not identify Spinozism through SP1, that monism is barely discussed, or that the identification of Spinozism proceeds through doctrines SP2-5, several of which Spinoza shared with non-Spinozist philosophers, is therefore very misleading.

Stang proposes that the reason for my omissions is that I take Spinoza as a “stalking -horse for dogmatic rationalism in general”. While it is true that that is how I view Spinoza, for the reasons stated above it isn’t true that this explains the alleged conflations of characteristically Spinozist and non-Spinozist doctrines.

It is indeed crucial to the book’s argument that also Kant views Spinoza as such a “stalking-horse”. In a passage that I admittedly quote too often in the book, Kant more or less says just as much (KpV, AA 5:101–3). Stang reproduces a part from this longer quote:

Therefore I do not see how those who insist on regarding time and space as determinations belonging to the existence of things in themselves would avoid fatalism […]. Hence, if this ideality of time and space is not adopted, nothing remains but Spinozism, in which space and time are essential determinations of the original being itself, while the things dependent upon it (ourselves, therefore, included) are not substances but merely accidents inhering in it. (KpV, AA 5:101–2)

According to Stang,

While Boehm quotes this passage several times he never fully explains or reconstructs Kant’s argument that if spatiality and temporality are properties of things in themselves then God is extended (SP2), everything else (ourselves included) is a mode of God (SP1), and every action is a necessary consequence of a preceding state (SP3). (Emphasis in the original)

In fact, Section 6 of Chapter 3 begins thus:

Returning to the second Critique passage, the crucial question is what argument brings Kant to conclude that those who regard space and time as properties of things-in-themselves are committed to regarding them as properties of God. His assertion draws on the proposition that it is arbitrary [to do otherwise] […]. Much of an argument [however] this is not, and it is therefore important to notice that Kant is in fact only alluding to an argument he had defended in the first Critique—namely, in the fourth Antinomy. (p. 125; emphasis in the original)

This statement is followed by a five-page reconstruction of Kant’s argument, and its connection to the Second Critique.

Somewhat surprisingly, Stang is more or less aware of this discussion. His claim that I never “fully” explain Kant’s argument ends up with a footnote referring to it and dismissing it offhand. (This practice repeats itself in the review, as we shall see.) To be sure, footnotes can often legitimately qualify propositions made in the main text. But when they flatly contradict them, perhaps the propositions themselves should have been reconsidered. Stang’s footnote contains no explanation of the five-page reconstruction of the argument, only a reference to it and the following dismissal:

He does, however, argue that this passage in the Second Critique is a reference back to the proof of the Thesis of the Fourth Antinomy (A458/B486) […]. There are reasons not to be satisfied with this, though. First, both the proof of the Thesis and the Antithesis appeal without further argument to the problematic claim in this Second Critique passage that if God is the cause of space and time then he is in space and time (A455/B483; A455/B483) […]. Secondly, Kant claims in the Second Critique that if God is in space and time then we are modes of him, something he does not argue for in the Fourth Antinomy. Thirdly, Kant’s argument in the Thesis of the Fourth Antinomy is from the PSR to the spatiotemporality of God, not from the latter to fatalism (as it is in the Second Critique passage). (Emphasis in original)

In fact, I do not refer to the “proof of the Thesis” of the Fourth Antinomy, as Stang says, but to the Fourth Antinomy much more generally. The reason is that Kant provides the argument that I turn to reconstruct not in the proof of the Thesis, but in the Observation. Stang’s quick claim that the fourth Thesis provides no “further argument” that could support my reading of the Second Critique is therefore true, but off the mark.

As I argue in the book, Kant’s argument in the Observation on the Thesis is based on a general principle that, he thinks, holds for cosmological arguments (the fourth Thesis gives a cosmological argument):

[S]omething regarded as a condition must be taken in just the same significance as it has in the relation of conditioned to its condition in the series, if it is to lead this series to its highest condition through a continuous progress. (A458/B486)

By this principle, Kant means to say that the grounding relation that obtains between the unconditioned and the conditioned members that it grounds has to be of the same type as that obtaining between the cosmological series’ conditioned members. As I argue in the book, I consider this demand plausible, because cosmological arguments proceed by positing the existence of an unconditioned being in order to explain the termination of a regressing explanatory series. Therefore, one is only justified in positing that unconditioned being if it can successfully fulfil this explanatory function. However, it can function as an explanation of the series’ termination only if it stands in the same grounding relation to the series itself as the series’ members stand to one-another: the unconditioned doesn’t explain the termination of a regressing series if it doesn’t share its essential property. As I point out—and make sure to clarify that I do not claim direct historical influence—the principle Kant provides de facto upholds, by the PSR, an idea captured by Spinoza’s EId2 (namely a thought can be determined by a thought, and a body by a body, but not a body by a thought [or vice versa]); or, similarly, by Spinoza’s EIa5 (namely, things that have nothing in common cannot be understood by means of each other).

As I point out in the reconstruction of the argument, Kant’s Observation on the Thesis applies this principle to transcendental realism. Transcendental realists view explanatory grounding relations among things in the world as spatio-temporal. Therefore, in order to explain how this worldly spatio-temporal series terminates by grounding it in an unconditioned being, the unconditioned being has to be spatio-temporal as well. When Kant all-too-briefly writes in the aforementioned Second Critique passage that he cannot “see” how transcendental realists “justify themselves” when allowing space and time to be “conditions necessarily belonging only to the existence of finite and derived beings but not to that of the infinite original being” (KpV, AA 5:101–2), when he writes in the Second Critique that Leibnizians cannot but fall back on Spinozism, he seems to be falling back on an argument, motivated by the PSR, that he had provided in the First Critique.

As I point out in the same reconstruction, this argument, if successful, only shows that transcendental realists must regard the unconditioned as spatio-temporal (what Stang calls SP2). This position is of course rejected by Leibniz and Wolff, but endorsed by Spinoza. The book nevertheless makes sure to point out that this is an argument for the so-called SP2 only, and therefore can only provide—on a first look—an argument for a part of what Kant claims in the Second Critique passage. Significantly, it does not seem at first to provide an argument for Kant’s Second Critique claim that if transcendental idealism is not adopted, Spinozist monism follows. There, Kant said also that if transcendental idealism is not adopted, all finite beings are “not substances but merely accidents inhering in it” (Stang’s SP1).

From this clarification, however, the reconstruction proceeds to show that, in fact, Kant’s Observation also provides an argument for monism. Very briefly here: if the unconditioned being exists in time (on this view, it does), then it always existed. But then, also the cosmological series following from it always existed as a whole: as Kant writes in the Third Antinomy, if a temporal unconditioned cause always existed, all its consequences would have also always existed (A444/B472). Stang’s second objection in the footnote is therefore inaccurate as well. In fact Kant does have an argument—or at least the resources for an argument from his position in the Antinomy, which I spell out in the book—for the claim that if God is in “space and time then we are modes of him”. After all Kant does say in the Fourth Antinomy that if the unconditioned is not a thing “distinct from the world”, it is just “the world itself” (die Welt selbst)(A456/B484).

Lastly, the third brief dismissal in Stang’s footnote—according to which Kant’s argument in the Fourth Antinomy Thesis proceeds “from the PSR to the spatiotemporality of God, not from the latter to fatalism (as it is in the Second Critique passage)”—is also inaccurate. For one thing, does Stang recognise that Kant provides an argument—“from the PSR”, i.e. just as the book actually did reconstruct it—for the spatio-temporality of God after all? His claim so far, both in the body of the text and in the beginning of the same footnote—a claim that indeed could have had crucial implications for the book’s thesis—was that the book offers no such reconstruction. Second, as we saw, the Fourth Antinomy argument as reconstructed also supports monism, not just God’s spatio-temporality. Necessitarianism goes hand in hand with monism. More generally speaking, as I try to show in my repeated treatment of the Second Critique passage, Kant’s claim in it maps onto Kant’s position in the antinomies as a whole. His general stance, according to which transcendental realists are committed to Spinozism (Stang’s SP1 and SP2) falls back on the structure of the unconditioned and its relation to the world, as discussed in the Fourth Antinomy. This structure corresponds to the aforementioned characterisation, offered early in the Antinomies, in which the unconditioned is conceived (on one alternative) as “consisting of the entire series in which all the members without exception are conditioned and only the totality of them is absolutely unconditioned” (A417/B445).

To overlook this discussion while complaining in bold terms that the book never reconstructs “Kant’s argument that if spatiality and temporality are properties of things in themselves then God is extended (SP2)” is one thing. To then actually refer to this reconstruction in a footnote but still ignore it—and, in the same breath, to claim that the book refers to Spinozism through SP2-5, held by Wolff and Leibniz, not to SP1—is another.

Stang argues next that “given the absolutely central role that the PSR plays in this book, it is striking that Boehm never clearly articulates what this principle is, nor does he distinguish different versions of it and their relative strengths”. He moves on to introduce eight different formulations of it enumerated from (i) to (viii). I shall not quote all of them here, because Stang continues to point out, accurately, that “[t]here are passages that suggest that Boehm thinks that (viii) is the PSR and that endorsement of anything else is a failure to live up to the true requirements of rationalism”. Stang’s (viii) is the principle according to which “all truths whatsoever have determining grounds and there is no infinite regress of grounds”. But it is rather misleading to say that “there are passages that suggest” that that is the version of the PSR assumed in the book, because it is obvious throughout the book that that is the version that I am assuming. To characterise the Spinozist commitment to the PSR—here, more than anywhere else, as a “stalking-horse” of dogmatic rationalism—I have repeatedly used the simplest and I believe most ambitious formulation, according to which ‘there are no brute facts’—for every thing, event or a state of affairs, there is the complete explanation of the thing’s existence.

More significantly, the book argues at some length that Kant’s “supreme principle of pure reason”, according to which if the “conditioned is given, the whole series of conditions, subordinated to one another—a series which is therefore itself unconditioned—is likewise given, that is, is contained in the object and its connection” (A307/B364)—is nothing but the formulation of the PSR addressed by Kant (and by the book). This version of the PSR is explained at some length, and distinguished carefully from Kant’s subjective formulation of the same principle: “[F]ind the unconditioned for the conditioned cognitions of the understanding, with which its unity will be completed” (A307/B364).

Here too, however, the claim that I never articulate my understanding of the PSR is modified with a footnote (i.e. footnote 10):

The closest he comes is distinguishing what Kant calls the logical principle of reason (for every conditioned object, find its condition) from the pure principle of reason (for every conditioned object, the unconditioned series of its conditions is given)[…]. But there are many things ‘the rationalist PSR’ could be (given in the main text) and each of these principles demands further explication. What does ‘condition’ (ground) mean here? And what falls within the scope of the ‘conditioned’? And does this principle allow for infinite regresses of grounds?

Again, Stang should have seen that his footnote doesn’t qualify his proposition, but contradicts it. For at pages 51–6 in the book, where I explain my understanding of the PSR with reference to Kant’s ‘logical’ and ‘pure’ principles of reason (following Michelle Grier, I call them P1 and P2), these questions are all answered in plain words: “Kant uses ‘conditioned’ here broadly, referring to anything that could be an object of cognition: any thing, event, or state of affairs which requires a condition other than itself in order to be given as a fact.” A footnote substantiates this by reference to Kant’s general use of ‘conditioned’ in the Dialectic to objects, events, etc. Then further: “A ‘condition’ is the cause or the reason of what would count as an explanation of a conditioned that is given as a fact. Following Baumgarten, Kant speaks of ‘conditions’ interchangeably with ‘grounds’, the latter being what one cites in an answer to a why-question.” Further still: “An unconditioned is thus an ultimate condition, an ultimate explanatory ground, of what is given as condition. It is ultimate in the sense that it does not itself require further grounds for being given (not, in any case, other than itself).”[10] Lastly, I specify that when Kant speaks of the condition or the unconditioned “as ‘given’ (gegeben), he seems to mean that they exist”. (A footnote substantiates this claim by reference to his interchangeable use of ‘given’ and ‘exists’ in other antinomies.)

Knowing some of Stang’s work, which I appreciate, I have no doubt that valuable comments and criticisms of the book’s argument could be found in his sixty-odd pages long commentary. But distilling them here from the review’s uncharitable gross misrepresentations—coupled with denunciations in the harshest possible terms—would require a generosity that I do not have. Perhaps another occasion will one day be found.

Received: 30 December 2016.


[1] See e.g. Beiser (1987) or Lord (2010).

[2] For equally unequivocal statements, some of which I provide below, see also V-Met-K3E/Arnoldt, AA 29:132 and V-Met-L2/Pölitz, AA 28:567.

[3] My significant disagreement with Israel concerns his characterisation of Spinoza as a ‘radical Enlightenment’ thinker and of Kant as an arch ‘moderate Enlightenment’ philosopher. For a brief interaction with Israel’s work, see my review of his ‘radical Enlightenment trio’.

[4] Kant says that the Leibnizians show “shrewdness” but not “sincerity” when they hope that no one would notice that their position collapses into Spinozism (KpV, AA 5:102). 

[5] My position here is heavily indebted to Michael Della Rocca’s argument in Della Rocca (2014).

[6] Much more needs to be said here. For one thing, Kant almost certainly did not read Hume’s Treatise. But I’m not suggesting here that Kant actually took such realisations about Spinozism from Hume. Another point is that Hume’s impotence vis-à-vis Spinoza can be stated even more boldly. Della Rocca argues in the aforementioned chapter that, in fact, Hume cannot assume, without begging the question, that causes and effects are distinct things. He can only assume that “If there are causally and thus necessarily connected things, then those things are merely rationally distinct” (emphasis added). Hume is therefore, according to Della Rocca, “playing with fire”: given his repeated assumption of “rationalist friendly” principles, he may end up committed to a Spinozist view according to which all apparently distinct things are merely rationally distinct, and that there are causal connections after all. From the perspective of this argument—which of course is only insufficiently presented here—one can provide a particularly bold version of Kant’s statement that “transcendental realists are committed to Spinozism”. For Kant did, for better or worse, view Hume as a transcendental realist.

[7] See also Andrew Chignell (2009:157–8) and Chignell (2012:651). Note however that I do not wish to make too much of Kant’s “subscription” to the PSR in this reference, which is done somewhat indirectly.

[8] To be sure, I do agree that the unrestricted version of the PSR is false—for reasons that I explore in the book’s fourth Chapter—and arguably incoherent, for reasons that I shall not elaborate here.

[9] I actually disagree with Conant’s reading of Descartes as a Cartesian sceptic. Neither Descartes, as attested by his evil deceiver hypothesis and its connection to his controversial doctrine of the creation of the eternal truths, assumes thought’s possibility. (Conant of course is aware of this challenge, but more or less dismisses it by adopting Frankfurt’s weak interpretation of the creation of the eternal truths. There is no need to enter this debate here.)

[10] In his comments, Stang offers here an argument for the claim that the unrestricted formulation of the PSR is “incoherent” because identities are primitive (they just cannot have “grounds”, he argues). While I do believe that the PSR’s unrestricted formulation is ultimately false, perhaps even incoherent, I do not think that that is the case for the reasons marshalled by Stang. Spinoza can reject primitive identity if substance’s identity is self-explanatory, and all other identities are given through substance. Stang offers here this example: “2 is the successor of 1. What is the ground of this truth? Perhaps, it is grounded in the essence of 2, the fact that to be 2 is to be the successor of 1. What grounds that truth? At this point, it is very plausible that we hit explanatory bedrock.” Spinoza wouldn’t be bothered by this example because he would deny that numbers in general can be spoken about properly (or thought about adequately); indeed he would even deny that substance properly speaking is ‘one’. See for example CM I 6; G I 246; or his letter to Jarig Jelles (50), June 2, 1674, G IV 240. I’m drawing here on the recent work of Mogens Laerke (2012) as well as an unpublished paper by Della Rocca.



Beiser, F. (1987), The Fate of Reason: German Philosophy from Kant to Fichte (Cambridge, MA: Harvard University Press).

Chignell, A. (2009), ‘Kant, Modality, and the Most Real Being’, Archiv für Geschichte der Philosophie 91(2): 157–92.

——— (2012), ‘Kant, Real Possibility, and the Threat of Spinoza’, Mind 121(483): 635–75.

Conant, J. (2003), ‘Varieties of Scepticism’, in D. McManus (ed.), Wittgenstein and Scepticism (London: Routledge), pp. 97–136.

Della Rocca, M. (2014), ‘Playing with Fire: Hume, Rationalism, and a Little Bit of Spinoza’, in M. Della Rocca (ed.), The Oxford Handbook for Spinoza, published online March 2014 (New York: Oxford University Press).

Lærke, M. (2012), ‘Spinoza’s Monism? What Monism?’, in P. Goff (ed.), Spinoza on Monism (Basingstoke: Palgrave Macmillan), pp. 244–61.

Lord, B. (2010), Kant and Spinozism (Basingstoke: Palgrave Macmillan).

© Omri Boehm, 2017.

Omri Boehm is Assistant Professor of Philosophy at the New School for Social Research, New York. Boehm obtained his Ph.D. from Yale University in 2009. He teaches and writes on early modern philosophy and philosophy of religion, with a specific focus on Descartes, Spinoza and Kant. His book The Binding of Isaac: A Religious Model of Disobedience was published in 2007 with Continuum (pb Bloomsbury 2014). In addition to his academic publications, he also writes, among others, for the LA Review of Books, the Boston Review, Haaretz, Die Zeit and the NY Times. He is currently writing a book on Descartes with the working title Passion, Freedom, Reason: a Rereading in Descartes.