This chapter has two aims. First, I want to provide an interpretation of Kant’s critique of dogmatism, with Christian Wolff as the chief defender of that approach. I distinguish between three different characterizations of dogmatism that Kant provides. I show that Kant regards Wolff as a dogmatist in two of these senses and explain how he can consistently hold that view. Second, I aim to offer an account of Kant’s views on the relationship between his ‘critical’ method and Wolff’s ‘dogmatic’ method, since Kant suggests that the latter is not without its merits.

This chapter documents the widespread influence of experimental philosophy in eighteenth-century Germany. We first argue that Christian Wolff, the most influential German philosopher of the period, engaged at length with the methodological views of experimental philosophers and relied extensively on experience as the foundation of his own philosophy. However, his focus on developing a comprehensively deductive philosophical system ultimately overshadowed his commitment to basing philosophy on experiments and observations. We then show how the pair of experimental and speculative philosophy became enshrined in the structure of the Berlin Academy as a result of the rebranding of its disciplinary classes in 1746. Turning to the second half of the eighteenth century, we focus on the uptake of the methodological views of experimental philosophers in the literature on empirical psychology that flourished in the period; the reflections on the relation of experimental and speculative philosophy of Johann Nikolaus Tetens, a proponent of empirical psychology who influenced Immanuel Kant; and the contrasts between experimental and speculative methods in a range of works published toward the end of the century. As Kantian and post-Kantian philosophies rose in popularity, a priori reflection gained increasing acceptance and experimental philosophy went out of fashion.

By the turn of the twentieth century, many philosophers claimed that Kant’s philosophy of mathematics (and, indeed, his entire philosophy) was undermined by the real possibility of geometries in which Euclid’s axiom of parallels is false. It is surprisingly not well known that Kant – though never discussing parallel lines in his published work – did write a series of unpublished notes on the philosophical problems posed by parallel lines. This paper presents the argument and chief issues of these notes. Kant’s main point in these notes is that neither Euclid’s definition of parallel lines, nor the alternative definition proposed by Leibniz and Christian Wolff, fulfills the requirements on mathematical definitions that Kant explicates in the Critique of Pure Reason. Thus, these notes show that Kant did reflect on the problems posed by the theory of parallel lines and recognized that it was uniquely problematic. Moreover, Kant’s reflections yield new insights about his philosophy of mathematics. In particular, Kant’s attitude toward the theory of parallels demonstrates that he had a novel theory of mathematical definitions, axioms, and postulates – a theory that Kant’s contemporary readers have largely misunderstood.