 Like adverbialists, the intentionalist has no need to postulate non-ordinary perceptible entities in the cases of illusion and hallucination. It is not generally true that when a representation represents something (as being F), there has to actually be something (which is F). Thus, for the intentionalist, experience is representational in a way that contrasts with it being relational/presentational. Experience does not genuinely have an act-object structure. This is in keeping with a standard tradition in the theory of intentionality which treats it as non-relational (the tradition derives from Husserl (1900/1901); for discussion see Zahavi (2003: 13–27). So, for the intentionalist, since it is not of the essence of experience or its character that it is relational, it is not of its essence that it is a relation to a sense-datum.