 Externalism and internalism about contents are distinct theses from externalism and internalism about phenomenology. Internalism about phenomenology is the thesis that intrinsic duplicates are phenomenal duplicates. Externalism about phenomenology is the denial of this thesis, on the grounds that phenomenology is determined in part by factors outside a subject’s skin. Externalism about phenomenology is sometimes motivated by representationalism about phenomenology combined with externalism about content. If one is externalist about experiential content, and if one holds that the content and the phenomenology of an experience co-vary, then one must also be an externalist about phenomenology. This thesis is defended by Dretske (1995) and Lycan (2001), and criticized by Block (1990) and (1996). For further discussion, see the entry on  external theories of content.