Kant’s Critique of Spinoza by Omri Boehm (review)

In a brief review I cannot do justice to the wide variety of interesting claims Omri Boehm attempts to establish. While Boehm’s arguments achieve varying degrees of success, it is worth noting up front that, even taken alone, his addition to the literature on contemporary considerations of the principle of sufficient reason (PSR) in chapter 4 is well worth the price of admission. The end of chapter 3 and the entirety of chapter 4 consider whether Immanuel Kant is successful in offering an alternative to substance monism and what this consideration has to tell us about contemporary debates concerning metaphysical rationalism and the status of the PSR. The primary claim of chapter 4 is that the PSR cannot be justified independently of the ontological argument for the existence of god. The PSR requires the existence of a being that is the cause of itself, a notion that is unintelligible unless existence is a predicate. Thus rationalist proponents of the PSR are committed to the claim that existence is a predicate. Boehm argues for this claim directly and then reinforces his argument by attempting, along Kantian grounds, to undermine Michael Della Rocca’s recent alternative argument for the PSR. These significant claims will certainly merit detailed analysis in any further additions to the relevant literature.

In chapters 1 and 5, Boehm argues for the historical claim that Kant, before the critical turn, was himself a Spinozist. The Critique of Pure Reason (CPR) represents Kant’s rejection of his own earlier monism. Thus, Kant’s reaction to the developing Pantheismusstreit explains the “change in tone” from the “A” to the “B” editions of the CPR. Boehm’s bold historical claim that the CPR should be read as Kant’s critique of his own earlier Spinozism relies on two primary pieces of evidence. First, Kant’s early Spinozism is supported by Boehm’s reconstruction of Kant’s argument for the existence of God in the Beweisgrund as committing Kant to substance monism. Second, Boehm claims that only Baruch Spinoza fits the description of the dogmatic metaphysician Kant counters in the Critique.

As Boehm reconstructs Kant’s proof, it relies (at a step Boehm labels D3) on the PSR. However, Kant does not explicitly mention the PSR as playing any role in the argument. In fact, Kant’s discussion later in the text (AA 2:158) of Christian Wolff’s argument for the existence of God criticizes Wolff’s proof because it rests on the disputed PSR. It is difficult to see how Kant’s claim is sensible if his own argument also requires the principle. Boehm does not address this worry, and I find his reconstruction implausible in light of it.

In arguing for the claim that only Spinoza could be the dogmatic metaphysician Kant wishes to undermine in the Critique, Boehm notes that he is unaware of Kant’s criticizing any philosopher other than Spinoza for the use of “arbitrary definitions,” a tactic borrowed from mathematics but inappropriate for philosophy. This comment is in concert with Boehm’s earlier claim that though other philosophers use a mathematical method, “none uses definitions, axioms, and demonstrations as Spinoza does” (4). Though I am uncertain of the import of the phrase “as Spinoza does,” there is ample evidence that Spinoza is not the only philosopher to use definitions, axioms and demonstrations; nor is he the only one Kant criticizes on this account. While Gottfried Wilhelm Leibniz himself provides no demonstration of the PSR in his published works, Wolff and Alexander Baumgarten both give geometric-style demonstrations for the PSR, and Kant repeatedly criticizes their proofs. No evidence is provided for rejecting Wolff, Baumgarten, or even Moses Mendelssohn as the targets of Kant’s repeated denunciations of dogmatic metaphysicians. Indeed, the failure to differentiate the position of Leibniz from the “Leibnizian” position of his followers is a problem that plagues chapters 2 and 3 as well.

Chapters 2 and 3 primarily consider an interpretive claim, namely that the Antinomy is...