|
|
|
|
|
|
||
|
|
|
|
|
|
||
|
|
||
|
|
|
|
Descartes separates corporeal substances from thinking substances; nature from spirit. Substances are known through their attributes, and each substance has an eminent property that defines it essentially (other properties being derivative). Corporeal things possess 'extension' (length, breadth and depth) eminently.
Descartes's universe is of three substances:
Substances are characterised by not needing anything else for their existence. By this criterion the only true substance is God. However, within the created order it is justifiable to declare matter and spirit as two finite substances as each can exist without the other.
The word 'being' is applied to God ('God is') and the substances of the created order ('the world is'). It cannot be applied in an identical way as there is evidently an 'infinite' difference between God and the finite substances of creation. If it were possible to declare the meaning of being common to all three substances then it would be possible to clarify the being of corporeal things (i.e. Descartes' world of objects with extension). Descartes does not do this, indeed Heidegger states that he evades the question, so the meaning of the being of a substance remains unexplained. In fact Descartes makes plain that since 'being' is not itself a being it consequently 'does not "affect" us' and 'therefore it cannot be perceived'. So, to bring definition to his idea of substance Descartes employs the attribute of extension but its being, as such, is overlooked:
'Thus the ontological grounds for defining the 'world' as res extensa have been made plain: they lie in the idea of substantiality, which not only remains unclarified in the meaning of its Being, but gets passed off as something incapable of clarification, and gets represented indirectly by way of whatever substantial property belongs most pre-eminently to the particular substance.' (M&R)
Heidegger is quick to declare that Descartes is blind to the phenomenon of world, or even the character of things in the world. Descartes fails to let the world be seen because he forces its phenomena into a mould of his own. Uncritically accepting the orientation of the past Descartes accesses the world by knowing it. Mathematical knowledge is most certain of all, so whatever has the ability to be apprehended in this way most truly is. This type of being is 'what always is what it is', i.e. what constantly remains. So this manner of being is forced upon the world: 'The kind of Being which belongs to entities within-the-world is something which they themselves might have been permitted to present; but Descartes does not let them do so (M&R)'. Instead he 'prescribes to the world... its 'true' being on the basis of an idea of being (being = constant objective presence) the source of which has not been revealed and the justification of which has not been demonstrated.'
Adopting a Cartesian view means that 'the kind of being that belongs to sensory perception is obliterated, and with it the possibility of grasping the being of those beings encountered in such perception'. Also 'it blocks the possibility of bringing to view attitudes of Da-sein in a way which is ontologically appropriate' and of 'seeing the founded character of all sensuous and intellective apprehension, and to understand them as a possibility of being-in-the-world'.
Whether Descartes can offer an understanding of material nature as the foundation of the world is considered. The need for this is well expressed by Mulhall:
Heidegger declares such a synthetic description of the world of value invalid, though a full discussion is reserved for later.