Bridging Kant and Quantum Mechanics: The Enduring Relevance of Things in Themselves and Appearances

This article aims to contribute to the literature by demonstrating the relevance and applicability of Kant’s distinction between things in themselves and appearances within the framework of wave-particle duality. The paper is divided into three sections. The first section clarifies two conceptions of appearances: as representations and as objects of representations. It also raises three key questions: (1) How can we access knowledge of the existence of things in themselves, if at all? (2) What roles do things in themselves play in Kant’s epistemology and metaphysics? (3) What, if anything, is lost if things in themselves are omitted from Kant’s system? The second section provides an in-depth analysis of the two-aspect interpretation of Kant’s distinction, focusing on the works of van Cleve, Westphal, and Langton, and examines the phenomenological, ontic, and epistemic dimensions of the distinction. The third section introduces key concepts of quantum mechanics, such as superposition and the uncertainty principle, in a way that is accessible to non-experts and in relation to Kuhn’s incommensurability thesis. The study concludes that, in the tercentenary of his birth, Kant’s distinction between things in themselves and appearances continues to offer profound insights in the context of quantum mechanics.