ABSTRACT
Descartes' fundamental conception of an 'idea', as was said in chapter 2 above, was of an intrinsically representational mode of thought. In virtue of their representing function all ideas are like 'images of things', although Descartes did not, of course, mean by this metaphor that all ideas are sensory images involving the corporeal imagination. In the argument for God's existence which follows this explanation he drew the Scholastic distinction between the 'formal' reality or being of an idea and its 'objective' reality. The argument hinges on the traditional notion of a scale of reality or being, with God at the top followed in order by finite spirits, corporeal substances and, finally, modifications of these substances. Another premise is the principle that everything on this scale is the effect of something at least no lower on the scale than itself. The crucial question is, where on this scale does the (allegedly) innate idea of a perfect being fall? Judged by its 'formal reality' it has the lowly status of a non-substance, a mode of thought; but it also possesses 'objective reality', i.e. the level of being of its object, which gives it the highest status of all. It must therefore have been caused by a perfect being.108
