An Inconsistency in the Knowledge Argument

I argue that Frank Jackson's knowledge argument cannot succeedin showing that qualia are epiphenomenal. The reason for this is that there is, given thestructure of the argument, an irreconcilable tension between his support for the claim thatqualia are non-physical and his conclusion that they are epiphenomenal. The source of the tensionis that his argument for the non-physical character of qualia is plausible only on theassumption that they have causal efficacy, while his argument for the epiphenomenal characterof qualia is plausible only on the assumption that they are non-physical. Since these two argumentscannot be combined coherently, the most Jackson's argument can establish is thatqualia are non-physical.