Identity in Cognitive Science, Quantum Mechanics, and Metaphysics
Identity is the relation every object bears to itself and to no other thing. Thus understood, identity is a core concept in philosophy. Not only has identity been a topic of discussion since the birth of the discipline, it also plays a crucial role in explaining other concepts such as those of person, object, and number. For example, to understand what a person is, we must understand what it takes for a person to still count as the same person after going through a period of time in which it may undergo substantial change. Even though the notion is crucially involved in explanations of other concepts, the received view in philosophy is that identity is simple, unproblematic, and in no need of further explanation. This special status of identity is arguably what motivates an important recent trend in metaphysics. This trend consists in relying on notions of generalized identity to define other important metaphysical notions such as those of grounding, fundamentality, or essence, which have traditionally been assumed to be systematically related to that of identity simpliciter (see Correia and Skiles forthcoming; Fine 2015). The starting point of this project is the observation that the received view that identity is simple, unproblematic, and in no need of further explanation ignores the challenges arising from important philosophical arguments and the philosophical interpretation of certain aspects of quantum mechanics. Furthermore, studies in cognitive science might be understood as undermining the idea that the concept of identity is unproblematic.