The article examines the viability of called ‘the knowledge argument’ that was designed to prove the irreducibility of the subjective, phenomenal aspect of experience to the physical. It is argued that this argument can successfully be defended against its criticism. Its critics are represented here by two physicalist approaches: the mode of presentation hypothesis (here Paul Churchland), and the ability hypothesis (here David Lewis and Laurence Nemirow). The defense of the general soundness of the knowledge argument is based on some important insights on the issue in question of Frank Jackson and Howard Robinson. It is argued that the physicalist counterarguments to the knowledge argument seem inadequate. The article concludes that it appears that the knowledge argument has still kept a significant amount of its initial force.