Combining Minds: A Defence of the Possibility of Experiential Combination
Keywords: Composition
Consciousness
Explanation
Mereology
Metaphysics
Philosophy of Mind

This thesis explores the possibility of composite consciousness: phenomenally conscious states belonging to a composite being in virtue of the consciousness of, and relations among, its parts. We have no trouble accepting that a composite being has physical properties entirely in virtue of the physical properties of, and relations among, its parts. But a long-standing intuition holds that consciousness is different: my consciousness cannot be understood as a complex of interacting component consciousnesses belonging to parts of me. I ask why: what is it about consciousness that makes us think it so different from matter? And should we accept this apparent difference? `Combinationism' - the thesis that intelligibly constitutive composition is possible in the experiential realm - bears on many debates in the metaphysics of mind. Constitutive panpsychism's need for combinationism is at the centre of recent criticism of the theory, but physicalists also need an account of how the consciousness, or lack thereof, in two cerebral hemispheres and a whole brain, or a human being and their head, or a social group and its individual members, can be intelligibly related. And further back in history, the supposed simplicity of the soul was held to rule out any form of materialism, in a tradition of argument stretching from Plotinus to Brentano. With an eye to this diversity of debates, I examine the prospects for combinationists with a range of different background views about the nature of consciousness, the ontological status of the subject, the behaviour of the physical part-whole relation, and the notions of constitution and explanation themselves. The core difficulty for experiential combinationism is that subjects seem to be exclusive and independent in their experiences: no experience of one subject can belong to, or even be deduced a priori from the experiences of, another subject. This separateness is thought necessary to do justice to the privacy and subjectivity of experience, and seems to preclude the kind of ontological intimacy between subjects that combinationism demands. In my third chapters I show that this conflict is soluble; a weakened form of exclusivity still preserves the distinctive privacy of experience, and is compatible with a composite sharing the experiences of its parts. A second major problem concerns the unity, interdependence, or even holism often attributed to each subject's experiential field. In my fourth and fifth chapters I develop a framework for accommodating and explaining this unity while still allowing component experiences to belong to distinct component subjects. Each experience in a unified field has a phenomenal character akin to that of amodal perception, indicating the other experiences that it is unified with. Other challenges arise from particular sorts of wholes and parts. Panpsychists attribute consciousness to our smallest microscopic parts; this raises special problems concerning the grain and structure of consciousness, which I address in my fifth chapter. Other versions of combinationism attribute consciousness to large overlapping parts of a human being, parts capable of formulating self-referential thoughts. This generates problems for self-knowledge, which I address in my seventh chapter. And any combinationist, having claimed that consciousness in a thing's parts accounts for consciousness in the whole, must confront the issues I address in my sixth chapter, concerning those large disunified composite entities, such as galaxies or mereological fusions of people, which have conscious parts but appear to be unconscious.