Because human experience is always mediated by memory, language, expectations, and conceptualizations, humans cannot have awareness empty of all content.

PCEs are impossible because of the “kind of beings” that we are (Katz 1978, 59). It is a fact about being human that we can experience only with the aid of memory, language, expectations, and conceptualizations. Thus, we cannot have a “pure” awareness empty of all content. (Also see Section 4.2).