This is an excerpt from a report on The Unity of Consciousness and Sensory Integration conference at Brown University in November of 2011, written by Kevin Connolly, Craig French, David M. Gray, and Adrienne Prettyman, and available at http://networksensoryresearch.utoronto.ca/Network_for_Sensory_Research.html 3. How Should We Model the Unity of Consciousness? Once we determine the building blocks of consciousness, we still need to determine how they are assembled. Most philosophers think that, at least in normal cases, the experiences of a single subject at a single time are phenomenally unified. As a first pass, two experiences of a subject are phenomenally unified just in case there is something it is like for that subject to experience them together. Much of the discussion at the conference centered on how to understand this relation. On Tim Bayne's view, as noted above, phenomenal unity is understood in terms of subsumption: two experiences are phenomenally unified just in case they are subsumed by the same encompassing conscious state, where subsumption is an irreducibly phenomenal relation (2010, p. 16). During the conference panels and Q&A sessions, participants put forward various alternatives. First, along with Bennett and Hill, we might take phenomenal unity to be reducible without residue to the obtaining of one or more other "unity-making relations" among experiences, such as object unity or spatial unity (see question one). Second, we might understand phenomenal unity in terms of mere conjunction. Suppose, for example, that you simultaneously have a conscious experience of a sunset and a conscious pain. Alex Byrne suggested that in such a case there is no more to two experiences being phenomenally unified than that I experience them at the same time. Third, we could give some or other representationalist account of phenomenal unity. David Chalmers mentioned one possibility: two experiences are phenomenally unified just in case they represent their intentional objects as belonging to one and the same world. He added that the best representationalist view of 2 phenomenal unity holds that such unity involves mere conjunction. You hear someone speaking and see a cup, for instance, and conjunction is responsible for the phenomenal unity of your world model. Note that a conjunctive view of phenomenal unity would rule out the possibility that a single subject has multiple streams of consciousness. In her discussion of split-brain subjects, Elizabeth Schecter argued for a view on which subjects can have multiple streams of consciousness (see Schecter, 2010). On her view, some distinct conscious experiences in a subject are not phenomenally unified. For example, the same subject could consciously experience a mug in the left visual field, and a pencil in the right field, while having nothing it's like to experience the mug and the pencil together. If this is a coherent possibility, it suffices to show that there must be something more to phenomenal unity than a conjunction of conscious experiences. References Bayne, Tim (2010). The Unity of Consciousness. Oxford: Oxford University Press. Schecter, E. (2010). "Two Unities of Consciousness." European Journal of Philosophy. doi: 10.1111/j.1468-0378.2010.00439.x