Probably the earliest systematic concept of mind and body stems from the philosophy of the Greek philosopher Plato (429-347 BC). Plato, like Descartes, saw the mind as identical with the soul. However, unlike Descartes, Plato argued that the soul both pre-existed and survived the body, going through a continual process of reincarnation or "transmigration".

An important concept to bear in mind when considering Plato's understanding of the soul's relationship to the body is his "theory of forms". According to this view, each thing that exists on earth - or even as an object of language - has a corresponding "form" or perfect idea. So, in the example used by Plato, a simple thing such as a bed would be linked to the perfect idea of a bed that exists independently (which all other beds share). The same thing would also apply to such things as colours, moral values or types of animal. For instance, the thing that all the different shades of red have in common is that they all correspond in some way to the form, or perfect idea, of "red".

For Plato, the soul - or mind - obtained knowledge through recollection of these forms. By doing this the soul was simply returning to the state of knowledge which it had before birth. Because of this view, Plato's arguments for dualism centre on the relationship between reincarnation and the process of obtaining knowledge through acquaintance with the forms.

The Arguments

Plato presents 4 main arguments for dualism, which can all be found in the dialogue Phaedo.

(i) Coming to be and ceasing to be (The Cyclical Argument). This argument relies on the notion that opposites rely upon one another and in fact lead to one another. In terms of life and death, this leads to the conclusion that, if life leads to death, then death must also lead to life. So, the living come from - or are reincarnations of - the dead, which then die and are born again (and so on).

(ii) Knowing is Remembering (The Recollection Argument). The second argument is based on the idea that all knowledge is simply a form of recollection. This is proven by showing that a young, untutored boy, with no knowledge of maths or geometry, can be led to display or "arrive at" knowledge which he did not know he possessed. How, Plato argues, could he display such knowledge unless he were recollecting it?

(iii) The Indestructibility of the Soul (The Affinity Argument). The third argument attempts to prove that the soul - although it may arguably predate birth - also survives death. Since the body is mortal, changing and made up of different parts, the soul - which seems not to be composed of many parts - must therefore also be immortal and unchanging.

(iv) The Argument from Opposites. Since death is the opposite of life, and opposites are mutually exclusive, therefore when the body dies, life must go on.