This article is criticizing philosoph er Frank Jackson’s thought experi- ment (TE) “The knowledge argument”. Jackson’s goal of the experiment was to prove that qualia are non-physical entities. The TE turned out as having been built on premise which was not realizable from physical reasons. Furthermore, it appears that the experiment implicitly assumes biologically inadequate theory of the hierarchy of cognitive functioning domains of a (human) organism. David Hume’s theory was reminded, contrasting to Jackson's related concept of pro- positional contents and phenomenal mental states. There were also two modern naturalistic qualia interpretations proposed. The first one gives qualia into direct relationship with the neuroscientist Antonio Damasio’s theory of feelings. The second one refers to the neuroscientist Gerald Edelman’s thoughts of the evolu- tionary value and structure of qualia. Naturalistic interpretation of qualia con- cludes that qualia are multidimensional cognitive contents – processes whose meaning lies in the comprehensive evaluation of an experienced situation that is accessible to conscious experience. It is also argued in favor of the proposition that no amount of propos itional information can replace qualia – therefore sen- sory deprivation cannot be substituted by knowledge. This fact is due to limita- tions of reach of conscious or introspective structures of the human organism. Finally, the fundamental function of physicality in our mental life is reflected.