ABSTRACT
This chapter provides an introduction to an externalism which is explored with the relation between the mind and brain. The contents of the thoughts are in the head. When people think about something, they use their mind; the contents of their thoughts are located in their mind. And if they are of the view that minds are brains, then this likely means that the contents of their thoughts are within their brain. The thought experiment presents a case of the Earth and Twin Earth facts of existence of water. The questions are intended to get the philosophy students thinking about these problems. They have used these kinds of questions in seminars as the questions set for seminars, so they also think that they can be used to spark conversation and discussion. The chapter also gives a cursory sketch of some of the ways in which philosophers have responded to the thought experiment.
