The unity of consciousness

Abstract

I am currently enjoying a number of experiences: I can hear the sound of a dog barking in the distance, I can feel the pressure of my feet on the floor, and I can smell freshly brewed coffee. These experiences don't simply occur at the same time, they also seem to be unified in a certain way. More generally, it is often said that consciousness is necessarily unified. This claim raises three questions: (1) What exactly does it mean? (2) Is it true? (3) What implications does it have? Chapters one and two are concerned with the first question: what does it mean to say that consciousness is unified? I develop a conception of the unity of consciousness that is both substantive and plausible. I call this conception the "unity thesis". Roughly, the unity thesis says that any pair of experiences that a single subject of experience has at the same time must be contained within a single fully unified phenomenal field: they must have a conjoint phenomenology. Chapters three and four are concerned with the second question: Is consciousness necessarily unified? In chapter three I tentatively endorse an inconceivability-based argument for thinking that they are not. Of course, a priori arguments against the possibility of disunified subjects must be weighed against empirical considerations. In chapter four I examine the evidence for thinking that some people actually are disunified subjects, focusing mostly on the split-brain syndrome. I argue that empirical arguments against the unity thesis are inconclusive. Chapters five and six are concerned with the third question: what implications does the unity of consciousness have? In chapter five I argue that the unity thesis places constraints on our account of state consciousness: if the unity thesis is true, then certain influential accounts of consciousness are false. In chapter six I argue that the unity thesis also constrains our account of the self: if the unity thesis is true, then we need to think of the self in phenomenal terms.