Qualia ain’t in the head

Qualia internalism is the thesis that qualia are intrinsic to their subjects: the experiences of intrinsic duplicates (in the same or different metaphysically possible worlds) have the same qualia. Content externalism is the thesis that mental representation is an extrinsic matter, partly depending on what happens outside the head. Intentionalism (or representationalism) comes in strong and weak forms. In its weakest formulation, it is the thesis that representationally identical experiences of subjects (in the same or different metaphysically possible worlds) have the same qualia. These three theses are widely held—especially the first two. But with the addition of some relatively innocuous assumptions, they are inconsistent. Take color as an example. Consider Bill and Ben, ordinary humans who are enjoying color experiences with different qualia. Let x be a (possible) duplicate of Bill, and let y be a (possible) duplicate of Ben. Given a specific externalist theory of content (which need not be reductive), with some ingenuity we can plausibly construct different environments for each, such that the theory predicts that x and y’s color experiences have the same content; so, by (weak) intentionalism, they have the same qualia. By qualia internalism, x’s experience has the same qualia as Bill’s, and y’s experience has the same qualia as Ben’s, so x’s and y’s experiences differ in qualia; contradiction. Alternatively, since an intentionalist about color qualia will typically endorse the converse thesis that the color content of an experience supervenes on its color qualia, we can start with a pair of duplicates x* and y* in different environments and use content externalism to argue that their experiences differ in content. Since x* and y* are duplicates, their