The Unity of Consciousness

Abstract

Tim Bayne, The Unity of Consciousness, Oxford University Press, 2010, 341pp., $55.00 (hbk), ISBN 9780199215386. Tim Bayne’s The Unity of Consciouness is the most comprehensive treatment of the unity of consciousness to date. The main project of the book is to specify and defend a version of the unity thesis, the thesis that a subject’s experiences are necessarily unified. The discussion is clear, detailed, and empirically informed. Bayne is fair to his opponents, and his arguments are largely convincing. Overall, this is an impressive work. The book is divided into three parts: Part I specifies the unity thesis and provides relevant background material. Part II argues that the unity thesis is true. Part III discusses implications of the unity thesis. The notion of unity relevant to the unity thesis is phenomenal unity: Experiences are phenomenally unified just in case they are subsumed by a single conscious state, that is, just in case there is something it is like to have the experiences together. For example, a visual experience of a red apple and an auditory experience of a trumpet are phenomenally unified just in case there is something that it is like to experience the red apple while hearing the trumpet. It can also be useful to speak of phenomenal fields, where two experiences are in the same phenomenal field just in case they are unified. Bayne develops a mereological account of phenomenal unity: “[C]onscious states are phenomenally