What is the unity of consciousness?

Abstract

At any given time, a subject has a multiplicity of conscious experiences. A subject might simultaneously have visual experiences of a red book and a green tree, auditory experiences of birds singing, bodily Sensations of a faint hunger and a sharp pain in the shoulder, the emotional experience of a certain melancholy, while having a stream of conscious thoughts about the nature of reality. These experiences are distinct from each other: a subject could experience the red book without the singing birds, and could experience the singing birds without the red book. But at the same time, the experiences seem to be tied together in a deep way. They seem to be unified, by being aspects of a single encompassing state of consciousness. This is a rough characterization of the unity of consciousness. There is some intuitive appeal to the idea that consciousness is unified, and to the idea that it must be unified. But as soon as the issue is raised, a number of questions immediately arise: (1) What is the unity of consciousness? (2) Is consciousness necessarily unified? (3) How can the unity of consciousness be explained? These three questions can be seen as clustering around the status of what can be called the unity thesis (UT; Necessarily, any set of conscious state of a subject at a time is unified). This chapter will address all three of these questions. The central project will be to isolate a notion of unity on which the unity thesis is both substantive and plausible. That is, the authors aim to find a more precise version of the unity thesis that is neither trivially true nor obviously false. With such a thesis in hand, the authors will look at certain arguments that have been made against the unity of consciousness, to determine whether they are good arguments against the unity thesis as they understand it. And finally, after fleshing out the unity thesis further, the authors will apply the thesis to certain currently popular philosophical theories of consciousness, arguing that the thesis is incompatible with these theories: if the unity thesis is true, then these theories are false.