The word ‘dualism’ can be used to pick out at least four different theories concerning the relationship between mind and body.
(1) A mind and a body are two different entities and each is “had” by a man. A man is thus a composite being with two components, one “inner”, the other “outer”. You, for example, are a man and your mind is “inner” in the sense that you alone can reflectively experience yourself thinking, or feeling pain, or seeing colours (or at least that you alone can reflectively experience your own thoughts, feelings and visual experiences). I can in a sense observe you thinking, but only by observing you use your body in certain ways—e.g. to make certain sounds, write certain things, look at the pages of an open book and frown. My “experience” of you thinking (or of your thoughts) is thus not a reflective experience. Your body is “outer”, on the other hand, in the sense that you cannot experience it or its (non-relational) properties in any exclusive way. That is, in whatever sense you can be said to experience your body, someone else can equally be said to experience it.