The question of the unity of consciousness is often treated as the question of how different conscious experiences are related to each other in order to be unified. Many contemporary views on the unity of consciousness are based on this bottom-up approach. In this paper I explore an alternative, top-down approach, according to which (to a first approximation) a subject undergoes one single conscious experience at a time. From this perspective, the problem of unity of consciousness becomes rather the problem of how we can distinguish a multiplicity of goings-on within our conscious experience at any time, given that it is unique.
I will present three possible top-down approaches to unity of consciousness, which I call Priority unity monism, Existence unity monism, and Brentanian unity monism. Priority monism and Existence monism are defined in analogy with the homonymous metaphysical theories of object constitution. Brentanian monism retraces Franz Brentano’s view on unity of consciousness, and is defined by appeal to some of his mereological ideas. I will argue that the latter is the best top-down approach to unity of consciousness.