 Externalism about experience content (or experience-content externalism) is the thesis that subjects alike in properties that are intrinsic to them need not share the same experience contents. If experience-content externalism is true, then what makes it the case that an experience has the content it does depends on external relations to things outside the subject’s skin, such as social relations between the subject and others, or causal relations to things in the environment. Defenders of experience-content externalism include Dretske, Lycan, and Tye, all of whom argue for experiential externalism on the grounds that the alleged best naturalistic theories of intentionality for experience are externalist theories. (For discussion of externalism about the content of other mental states, see the entry on  external theories of content.)