This introductory chapter presents an outline of the metaphysics of identity and individuality, which emphasizes the conceptual distinction between individuality and distinguishability. The Principle of Identity of Indiscernibles effectively reduces the former to the latter, but notions of haecceity, ‘transcendental individuality’, and ‘space-time’ individuality are also presented, with the aim of laying the groundwork for the subsequent considerations of identity and individuality in the quantum context. In particular, as identity in higher-order logic is defined in terms of indistinguishability and ‘countable’ objects which feature in set theory are typically taken to be those which have well-defined identity conditions, this metaphysical framework will underpin the rest of the discussions in this book.
Keywords: individuality, distinguishability, haecceity, haecceitism, transtemporal identity, transcendental individuality, bundle theory, Identity of Indiscernibles