Volume 116, Issue 2

This paper examines and critiques Immanuel Kant’s strong opposition to espionage and related “infernal arts” as expressed in Towards Perpetual Peace  and the Metaphysics of Morals . While Kant condemns espionage as a dishonorable stratagem that undermines the trust essential for lasting peace, this stance has received limited scholarly attention. The paper argues that Kant’s rejection of espionage is more nuanced than a mere objection to dishonesty; rather, it is rooted in his political and legal philosophy, particularly his views on just war theory and the need for nations to establish a “rightful condition.” The analysis contrasts Kant’s views with those of Grotius and Hobbes. Critically, the paper challenges Kant’s position, suggesting that it aligns only with a narrow conception of espionage and overlooks its potential to foster international trust. By reassessing Kant’s arguments, the paper highlights their relevance to contemporary debates on the ethical dimensions of espionage and warfare.

Although Heidegger’s Kant and the Problem of Metaphysics has been extensively and critically discussed by Kant scholars, its main issue, as indicated by its title, has not received due attention. The notion of metaphysics presupposed by Heidegger is shaped by the project of fundamental ontology in Being and Time . However, the notion of metaphysics that he attributes to Kant bears little resemblance to Kant’s own understanding of the term. Consequently, the claim that the Critique of Pure Reason in some way anticipates Heidegger’s project, as well as the idea that this project constitutes a “revision” of Kant’s attempt to provide a foundation for metaphysics, fails to account for the fundamental differences between the two philosophers.

In this paper I argue that Kant’s investigation of the nature of bodies, although it was largely based on Newtonian science, was more dependent on notions and debates in German logic and metaphysics. In section 1, I introduce the role of material substance in the Metaphysical Foundations of Natural Science , arguing that the systematic framework of Kant’s “metaphysics of corporeal nature” cannot be described as a “foundation of Newtonian philosophy” and is best understood in the context of the reception of Newton’s physics in Wolffian metaphysics. In section 2, I analyze the crucial role of monads, monadology and materialism in the development of Kant’s dynamics. In section I3, I address Kant’s “continuum” theory of matter in the Metaphysical Foundations , pointing out that it depended on non-Newtonian (or post-Newtonian) models. In section 4, I examine the methodological background of Kant’s critique of the “solidity” of bodies, tracing it back to Kant’s earlier debate on the method of science and metaphysics with Johann Heinrich Lambert.

In the Metaphysical Foundations of Natural Science , Kant attempts to argue a priori from the indefinite divisibility of space to the indefinite metaphysical divisibility of matter. This is one type of argument from the continuity of space – purportedly established by Euclidean geometry – to the continuity of matter. I compare Kant’s argument to parallel reasoning in Du Châtelet, whose work he knew. Both philosophers appeal to idealism about matter in their reasoning, yet also face difficulties in explaining why continuity, though not some other properties from geometry, applies to matter. Both also risk inconsistency in adopting potentialist accounts of material parts, while also committing to realism about infinitesimals. An important difference between them is that Du Châtelet deploys at least three definitions of continuity; only one of these, amounting to indefinite divisibility, is shared with Kant.

The Mechanics chapter of the Metaphysical Foundations begins with the claim that the mechanical-derivative forces, which act between bodies, presuppose the dynamical-fundamental ones, through which bodies fill space. This article explores the historical context of Kant’s claim. The broadly Eulerian textbooks by J. P. Eberhard and J. C. P. Erxleben, which Kant used for most of his physics lectures, do not distinguish between fundamental and derivative forces, although they present views on impenetrability, the communication of motion, and elasticity that are close to positions Kant will defend. For the background to Kant’s claims about the relation between the mechanical and dynamical forces, we must turn to Wolff and Leibniz. I argue that on this issue Kant returns to Leibniz, although in a way that is informed both by Wolff’s scepticism about aspects of Leibniz’s philosophy and by the Eulerian textbooks.

Kant regards matter as not only extended but impenetrable. However, Kant distinguishes two senses of impenetrability: mechanical and chemical. Kant accepts the former as necessarily belonging to matter, but he denies, or at least sees no reason to accept, the latter. The kind of chemical penetration that Kant is concerned with occurs when no part of the one component matter exists unmixed with the other matter. Here, the two component matters come to fill the whole of the very same space. Kant distinguishes two kinds of process that can lead to such penetration: cases of “literal” dissolution of one matter (a solute) through being broken up by the other (the solvent), in which the former is divided into parts ad infinitum; and cases where the one matter simply progressively permeates the other. Kant considers problems associated with the former that he does not regard as at issue in the latter.

In this paper we examine Euler’s influence on Kant’s  Metaphysical Foundations of Natural Science  as a non-Newtonian source. We show that he is more than a mere mediator between Newton and Kant. Rather, Euler’s perspective on the relationship between mechanics and metaphysics as well as the law of inertia and space can be seen as paving the way for Kant’s critical project and his natural philosophy. To demonstrate this, we analyze key passages from Newton’s work and examine Euler’s Reflections on space and time. It becomes clear in this analysis that Euler, in contrast to Newton, reverses the relationship between metaphysics and physics as well as the law of inertia and space. This provides a new perspective on Euler’s influence on Kant and, on the basis of a critical discussion of the current state of research, allows a non-Newtonian source to appear in a new light.