In Language, epistemology, and mysticism , Steven T. Katz presents his theory of the interpretation of mystical experience reports in which the foundational epistemological claim is that there are no pure experiences . Around this claim, he developes a theory of interpretation that implies the rejection of a common core in mystical experience. This theory also involves a criticism against the so called perennial interpretations of mystical experience and of the phenomenal characteristics that are considered to be prevalent in mystical experiences across traditional religious boundaries. Katz s theory has been interpreted and criticised as a constructivist theory of meaning, implying cognitive relativism and non-realism for the experiences of mystics. As a theory of interpretation, purporting to be superior to the perennial models of interpretation, Katz s theory is evaluated in terms of their scientific value for the interpretation of mystical reports.