Kant’s Modal Metaphysics by Nicholas F. Stang (review)

Nick Stang offers an extremely meticulous and original study of Immanuel Kant’s theory of modality. It is the first book dedicated solely to Kantian modality in the Anglophone Kant literature, crowning the recent surge of articles on the subject, while also setting up a fertile ground for further discussion. The book’s appeal is not limited to Kant readers. Considering its historical focus and scope, Stang’s book is unusually rigorous, analytically argued, and well informed by twentieth-century modal metaphysics and logic, making it perfectly accessible to those who are interested in modality from a contemporary metaphysical point of view.

Stang presents a developmental account of Kant’s conception of possibility, from his pre-critical texts of the 1750s and 1760s to his critical works, including the Critique of Pure Reason (CPR), in two parts of five chapters each. Stang’s interpretation of Kant’s pre-critical conception of possibility is conveyed through a broader historical narrative, placing Kant in opposition to “logicism,” the doctrine that possibility (and necessity) can be fully accounted for in terms of the logical principle of contradiction. Stang claims that logicism is commonly held by Kant’s major rationalist predecessors (G. W. Leibniz, Christian Wolff, and Alexander G. Baumgarten) and is also what commits these figures to “ontotheism,” which maintains that God exists in virtue of his essence. Against logicism, Stang argues, Kant introduces a “real” or metaphysical conception of possibility, requiring not only that the predicates of a thing be logically consistent with one another but also that each predicate be “grounded” in actual things. Accordingly, some logically consistent combinations of predicates do not designate really possible objects that can actually exist. Although I think this narrative is a bit rough, conveniently dismissing Leibniz’s and especially Wolff’s efforts to formulate extra-logical conceptions of possibility, it serves Stang as an effective tool in delineating what is novel in Kant’s early deliberations about modality.

In the second part, Stang shows how Kant builds upon his pre-critical conception of real possibility an integrated system of different types of real possibility, with corresponding types of real necessity. Stang goes beyond a mere reconstructive account here, and argues that understanding this system is key to settling some important interpretative questions in Kant’s critical philosophy such as whether Kant conflates the necessary and the a priori (chapter 7); why Kant maintains that particular causal laws are necessary while he insists that they cannot be known a priori (chapter 8); how Kant can resolve the antinomial conflict between his claims that we, as noumena, have freedom, understood as the real possibility of willing otherwise, and that God’s intuitive intellect does not cognize modal properties of noumenal things such as ourselves.

The overarching claim that shapes Stang’s entire outlook on the subject is that the change in Kant’s approach to modality from his pre-critical to critical periods should be understood in terms of the transformation of the guiding question in Kant’s respective periods, from the ontological question, “what is it to be possible?,” into the transcendental question: “how do we represent possible objects a priori?” Therefore, on Stang’s account, the change in Kantian modality is a shift in perspective rather than substance and is a natural and even expected consequence of the overall critical turn in his mode of inquiry. This is indeed a plausible account, but perhaps less ambitious than it could be. For it ultimately treats modality as one of the many components of Kant’s thought that had to be reoriented around the critical turn. However, one wonders whether we can pursue a more radical outlook on the relationship between modality and the critical turn, assigning the former a constitutive role in the latter. The central and recurrent theme in Kant’s expositions of modal categories (possibility, existence, necessity) in the CPR is that there is something special or peculiar (besondere) about them: unlike all other categories that contribute to...