The Smythies-Carr (SC) hypothesis of phenomenal consciousness is a version of material dualism based on Brane theory in modern physics. In Cartesian Dualism the criterion for differentiation of mental events and physical events is that the latter are extended in space whereas the former are not (as Descartes's "unextended thinking spirits"). In the SC hypothesis the complex contents of phenomenal consciousness are composed of located, and extended, visual and somatic sensations and images, as well as located, but unextended, auditory, olfactory sensations and images, thoughts and the Self. These organized events, for one individual person, are located in a 3D space of their own ("phenomenal space") (A) external to common physical space (B). A and B are different cross-sections (or branes) of a higher-dimensional space (the bulk). Phenomenal events in a consciousness module are connected to events in that person's brain by causal relations.
The theory was first adumbrated by C.D. Broad in 1923 when he proposed that the phenomenal space of consciousness and physical space are two different slices in a higher-dimensional space (as we can cut two different planes in a cube). This theory was later supported and further developed by H.H. Price, Bertrand Russell and Lord Brain. Thus a human being consists of one unified organism. But this is not composed just of the physical body, but of the physical body plus a material consciousness module located in a parallel universe. The TV-like representative mechanism mediating vision, for example, consists of the retina, optic nerve, lateral geniculate nucleus, and visual cortex (all located in space B) and, in addition, the phenomenal visual field (located in Space A) where phenomenal objects are located. These may be examined by introspection. They represent external physical objects just as the images on a TV screen represent objects in the TV studio.
This hypothesis solves the binding problem and avoids the problem that the competing Psychoneural Identity Theory violates Leibniz's Law of the Identity of Indiscernibles. Current brane theory in physics postulates the existence of parallel universes but is conventional as to their possible contents. At present the theory is limited to supposing that the contents of all are similar to the contents of 'our' physical universe (i.e. composed for quarks, etc.) but with different physical constants. However, logically, a parallel universe could contain anything, including consciousness modules.
- John Smythies. (1994) "The Walls of PLato's Cave"
- (Aldershot, Avebury) and Bernard Carr. (2008) " Worlds apart?" Proceedings of the Society for Psychical Research, 59, 1-96.