Jose De Leon

One compelling argument challenging the tenability of physicalism, which sees reality as fundamentally comprised of physical facts, is Jackson's knowledge argument. Through a powerful thought experiment involving the case of Mary, the super neuroscientist, the argument demonstrates how knowledge of phenomenal facts cannot be deduced from knowledge of physical facts. For allegedly leaving out phenomenal facts in its account of reality, physicalism is shown to be incomplete and hence mistaken. Physicalists respond to this argument in a variety of ways, challenging, in turn, some aspects of the knowledge argument. This paper focuses on the replies of the ability hypothesis and the phenomenal concept strategy, which respectively try to block the two crucial moves in the knowledge argument: the establishment of an epistemic gap and the inference from the occurrence of this gap to the existence of an ontological gap. The paper critically examines how proponents of these two replies to the knowledge argument respond to some objections to maintain the viability of physicalism.