There is little consensus in the scholarly literature on Freud's position concerning the mind-body problem. Opinion is divided as to whether Freud was a dualist or a materialist. Amongst the advocates of the dualist interpretation, some scholars hold that Freud advanced an epiphenominalist view of the mind.²⁰ Others claim that he was a psycho-physical interactionist.²¹ Still others take Freud to have been a psycho-physical parallelist²². Amongst advocates of the materialist interpretation, most describe Freud as an identity theorist of an unspecified kind.²³ Others describe him as having settled on a token identitytheory.²⁴ A few argue that Freud's position shifted over time.²⁵