In chapter 1, I described the philosophy of mind as being the philosophical study of minded things just insofar as they are minded. And the general term which I introduced to refer to something with a mind was subject of experience – interpreting ‘experience’ here in a broad sense, to include any kind of sensation, perception or thought. I take it that the term ‘subject of experience’ is more extensive than the term ‘person’ – that is, that although all persons are (at least potentially) subjects of experience, not all subjects of experience are persons. This is because I think that at least some non-human creatures, such as chimpanzees, are certainly subjects of experience and yet that they may not be persons. It is perfectly conceivable that there should be non-human persons, but it is open to question whether any actually exist. What, then, is distinctive of persons as opposed to other subjects of experience? Just this, I suggest: persons are selves – that is to say, they are subjects of experience which have the capacity to recognise themselves as being individual subjects of experience. Selves possess reflexive self-knowledge. By ‘reflexive self-knowledge’ I mean, roughly speaking, knowledge of one's own identity and conscious mental states – knowledge of who one is and of what one is thinking and feeling.