Metaphysics, Mathematics, Certainty: the Pre-History of the Preface to Kant’s Metaphysical Foundations of Natural Science

Stefan Heßbrüggen-Walter

National Research University - Higher School of Economics, Russian Federation

Research on the preface to Kant’s Metaphysical Foundations of Natural Science focuses mostly on its role within critical philosophy e. g. with regard to the changes Kant made in the second edition of the Critique of Pure Reason, appearing one year after the Metaphysical Foundations. My presentation proposes to change the perspective and to ask how the text relates to ongoing debates on the status of natural philosophy in 18th century Germany and beyond. I will limit myself to two closely related problems raised by the text: Why is there a metaphysics of nature that must be regarded as a part of physics broadly construed (Naturlehre)? And why should physics aspire to apodictic certainty in order to count as science? My talk will proceed in two steps. I will first show how the preface relates to texts by Christian Wolff, John Keill, and Johann Georg Walch. In this, I will argue for two related theses: ● Whereas it may make sense to read the Metaphysical Foundations as a vindication of Newtonian physics (in the modern sense of the word), this does not imply the more far-reaching claim that they should be read as a vindication of Newtonian natural philosophy, too. Kant does agree with the Newtonians that mathematization of natural philosophy is unavoidable. But he concurs at the same time with Wolff that natural philosophy must be subordinated to metaphysics. And he shares the conviction with Walch that metaphysics should be regarded as part of physics in a broad sense of the word (Naturlehre, physica generalis). ● The question whether physics should strive for apodictic certainty causes disagreement between Wolff, Keill, and Walch. Whereas both Wolff and Keill believe that physical knowledge is capable of proof (with the notable difference that the reach of these proofs is controversial), Walch assumes that physical knowledge can at best be probable. I will then go on to show that these 18th century controversies have their roots in 17th century conflicts between Cartesians (Clauberg) and Eclectics (Sturm). Whereas Clauberg holds that natural philosophy must be subordinated to metaphysics and is capable of apodictic certainty, Sturm opts for an experiential approach leading at best to probable hypotheses and discarding any metaphysical grounding of natural philosophy in the process. On a cautionary note, I want to add that Kant’s theory of natural science is of course more than just a collage of Wolff, Walch, or Keill. However, the pre-history of the preface suggests that the differences in opinion to be observed in these texts may at least in part due to differences in ‘metaphilosophical’ commitments. What natural philosophy should strive to achieve, can only be judged in the light of what philosophy as a whole is taken to be.