The partial brain thought experiment: partial consciousness and its implications

Abstract

The ‘Fading Qualia’ thought experiment of Chalmers purports to show that computationalism is very probably true even if dualism is true by considering a series of brains, with biological parts increasingly substituted for by artificial but functionally analagous parts in small steps, and arguing that consciousness would not plausibly vanish in either a gradual or sudden way. This defense of computationalism inspired an attack on computationalism by Bishop, who argued that a similar series of substitutions by parts that have the correct physical activity but not the correct causal relationships must likewise preserve consciousness, purportedly showing that ‘Counterfactuals Cannot Count’ and if so ruining a necessary condition for computation to meaningfully distinguish between physical systems. In this paper, the case in which a series of parts are simply removed and substituted for only by imposing the correct boundary conditions to exactly preserve the functioning of the remaining partial brain is described. It is argued that consciousness must gradually vanish in this case, not by fading but by becoming more and more partial. This supports the non-centralized nature of consciousness, tends to support the plausibility of physicalism against dualism, and provides the proper counterargument to Bishop’s contention. It also provides an avenue of attack against the “Fading Qualia” argument for those who remain dualists.