Kant and Rational Psychology by Corey W. Dyck (review)
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It is widely understood that Kant closed down the project of rational psychology in the Paralogisms chapter of his Critique of Pure Reason (1781/1787; A341–405/B399–432). Kant described rational psychology as “a putative science built on the single proposition I think” (A342/B400), a science that Kant found wanting, such that “the whole of rational psychology collapses . . . and nothing is left except to study our soul following the guideline of experience” (A382).
This has traditionally been understood as a rebuke of the “narrowly rationalist psychology” of Descartes and Leibniz that purports to develop a psychology free of all empirical content, grounded exclusively on the Cartesian “I think,” from which are deduced a priori claims of a self that is (1) substantial, (2) simple, (3) an enduring person, and (4) related problematically to external objects, whose existence is uncertain—these claims being the conclusions of the four paralogisms discussed by Kant.
If Kant’s target was Descartes, however, then much of this text is puzzling—for example, when Kant complains of the rational psychologists trying to give an empirical ground to the unity of the soul, which for Kant is a merely formal unity (A354–61). The book under review makes a detailed and well-argued case that Kant’s actual target was instead the rational psychology being developed and debated in eighteenth-century Germany, beginning with Christian Wolff. Unlike the pure rational psychology demanded by Kant in the Critique, this was a rational psychology with an empirical foundation. Psychology was understood by Wolff as a single science, and rational psychology consisted of what could be inferred from premises drawn (in part) from empirical psychology. Apart from getting the history closer to the truth and setting Kant’s discussion in its natural (and normally unstated) intellectual context, this shift in focus clarifies otherwise puzzling aspects of Kant’s arguments.
The author draws widely from the source material of eighteenth-century German metaphysics, few of whose players, apart from Wolff and Moses Mendelssohn, are much read today: Ludwig Philipp Thümmig, Alexander Baumgarten, Georg Bernhard Bilfinger, Israel Gottlieb Canz, Christian August Crusius, Johann Christoph Gottsched, Martin Knutzen, Georg Friedrich Meier, Jean Bernard Mérian, Johann Gustav Reinbeck, Johann Peter Reusch, and Andreas Rudiger, among others. Most were Wolffians of one sort or another, although a few were deeply critical of Wolff, such as Rüdiger and his student, Crusius. What one discovers is a flexibility and sophistication within the rationalist tradition that is all too often either ignored or caricatured, and the arguments rehearsed in this literature are often echoed in Kant’s published and unpublished writings.
When considering Kant’s critique of rationalist metaphysics, it is also worth recalling that he lectured on this same metaphysics more than fifty times during his teaching career, including the fifteen years following the publication of his Critique of Pure Reason, and that we have student notes of these lectures ranging from the early Herder notes (1762–64) to the late Vigilantius notes (1794–95). These lectures were nearly all based on Baumgarten’s Metaphysica (4th ed.: 1757), discussing in turn ontology, cosmology, psychology, and natural theology, with psychology further divided into empirical and rational. Kant also began lecturing on anthropology in 1772, the first part of which was based on Baumgarten’s empirical psychology, so that Kant was lecturing on empirical psychology in both his metaphysics and his anthropology lectures, and our author makes excellent use of these materials in his reconstruction of Kant’s development. [End Page 336]
The book under review consists of seven chapters, each an important study in its own right. Chapter 1 introduces Wolff’s psychology, while chapter 2 charts the development of rational psychology among Wolff’s followers and critics and the pre-critical Kant, drawing on Kant’s early publications, as well as reflections, correspondence, and student lecture notes (primarily the L1 metaphysics notes dating from the late 1770s, and which fortuitously include the most extensive discussion of rational psychology of all...
