restricted access Kant's Transcendental Proof of Realism (review)
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Reviewed by
Kenneth R. Westphal. Kant’s Transcendental Proof of Realism. New York: Cambridge University Press, 2004. Pp. x + 299. Cloth, $80.00.

Westphal's book is a rich and exciting contribution to the field of Kant studies. Its claims run counter to much contemporary discussion of Kant's theoretical philosophy and indeed challenge some of Kant's fundamental doctrines, but the arguments are very compelling and therefore likely to force us to rethink both the Critique of Pure Reason [CPR] and Kant's relevance to contemporary epistemology.

The central point of this work is that, if we follow Kant's injunction to engage in reflection on our cognitive capacities, then we will be led not to Kantian transcendental idealism but to an unqualified realism about objects and events in space and time. The book's first three chapters are devoted to analyzing Kant's methodology and the much-overlooked idea of transcendental affinity. Westphal focuses on the Kantian duty of engaging in "transcendental reflection," which is "the action through which I make the comparison of representations in general with the cognitive power in which they are situated, and through which I distinguish whether they are to be compared with one another as belonging to pure understanding or to sensible intuition" (CPR, A 261/B 317). And he adds to this the more general methodological obligation of "epistemic reflection," or the duty to determine precisely our cognitive capacities and incapacities. If, then, we reflect on our representations, their origins in sensibility and the understanding, and on our powers to know things of ourselves and the world in general, then certain puzzles arise—puzzles that were confronted by Kant (and Hume and Hegel) but that have not received the attention they have deserved. Chief among these puzzles is our ability to identify single objects and events and track them in space through time. But, as Westphal is keen to point out, identifying any particular over time requires that we be able to re-identify that particular. Now, while this puzzle is addressed by Kant in the Transcendental Deduction and Analogies of Experience, it is important to see that there is a material condition necessary for the possibility of self-conscious experience of the world that is not fleshed out in great detail by Kant and seems to be completely overlooked in the literature on Kant, namely, "the presupposition of diversity in nature" and the homogeneity of its objects among themselves (CPR, A 657/B 685). In other words, the fact that we are able to associate our various sensations with each other at all (and thereby identify and re-identify objects) is due to their "transcendental affinity." And it is Westphal's contention that "on Kant's own principles, the transcendental affinity of the manifold of sensory intuition can only be reconstructed, but not constructed, by intellectual syntheses of the understanding" (91). Therefore, pace Kant, who held that only his transcendental idealism could explain the possibility of experience, Westphal argues that transcendental idealism runs afoul of many of Kant's own arguments and observations in the Transcendental Aesthetic and Transcendental Analytic and, more important, that transcendental affinity provides grounds for "realism sans phrase" (the author's phrase) about objects and events in space and time, and for the view that our mental states are determined by external objects. As Westphal puts it in his conclusion: "Kant's analysis of transcendental affinity is in fact a transcendental argument for mental content externalism" (266). [End Page 665]

The second part of Westphal's argument revolves around a detailed examination of Kant's theses about transeunt causality and the nature of matter as expressed not only in the Critique of Pure Reason, but also in the Metaphysical Foundations of Natural Science and the Opus postumum. Roughly the problem is this: in order to have an adequately grounded metaphysics of nature, Kant needs not only the results of the Analogies of Experience, the transcendental causal thesis that every event has a cause, but also the metaphysical causal thesis that every physical event has an external physical cause. But, according to Westphal, in the Metaphysical Foundations and elsewhere, Kant fails in his...