Abstract

Kant rejects Leibniz’s Principle of the Identity of Indiscernibles. In quantum mechanics, Leibniz’s principle is also apparently violated. However, both ways of rejecting the PII differ significantly. In particular, Kant denies that spatiotemporal objects are unique individuals and establishes appearances as merely singular ones. The distinction between ‘unique’ and ‘singular’ individuals is crucial for the role that intuition plays in cognition: it will be shown that Kant’s way of rejecting the PII goes against the standard versions of conceptualism and non-conceptualism which, in turn, points out the relevance of this issue for the understanding of transcendental idealism. Finally, the systematic relevance will be checked by defending a Kantian interpretation of quantum individuality.