Grant that intentional content, subjective perspectivity and qualitative character supervene on and covary with neural events and neural properties, and grant that the latter are core and even differential realizers of the former. Grant that nothing much less complex than widespread activity in the thalamocortical system is implicated as the neural realizer of any conscious property. Grant all of that – it's another question whether even this widespread field of neural activity is itself enough for conscious property instantiation. Perhaps the base relative to which all the conscious properties are higher-order or emergent is composed not only of neural assemblies and their activity, no matter how many of them there are or how sophisticated that activity is, but also of extracranial objects and events and their activity. If so, then not only would conscious properties and events not be realized by individual neurons, dedicated neural assemblies, or widely distributed networks of activity in numerous neural assemblies, they would not be realized only by the brain. In that case, consciousness would, in one way of thinking about it, no longer be in our heads.

In this chapter, arguments for the conclusion that the conscious properties of content, qualitative character and subjective perspectivity are in part extracranially constituted are detailed. If properly qualified, content and qualia externalism are true and have consequences for particular kinds of reduction. The case of externalism about subjective perspectivity is another matter – here there is little reason to think that externalist arguments gain traction. More radical forms of externalism, as advocated by vehicle externalists, are shown to be too strong.