The nature of ideas; how God acts on the understanding; and how ideas can be illusory: a critique of Descartes’ supposed proof for God’s existence.

Abstract

This article initiates the epistemology section of the Discourse, which will continue through article 29. It begins with a definition of ‘idea’, found elsewhere, as ‘something which is in our mind.’ An idea is not necessarily the object of thought while we are thinking since we can have many ideas in our mind without thinking about them. But Leibniz’s main assertion in this article is that the idea of God, namely, that of a being having all perfections, which Descartes uses as a premise in his version of the so-called ‘ontological argument’, has not be shown to be a possible idea. That is, the idea of a being having all perfections has not been shown to be clear of internal contradiction. It is then shown, from an earlier work, how Leibniz proves it is possible for no contradiction to occur in the idea of a subject, namely God, possessing all perfections, where ‘perfection’ is defined as a simple, positive, maximum quality. Leibniz can then go on to claim in the Discourse that since the idea of God is possible, God’s existence is necessary. The particulars of Leibniz’s proofs are explained in detail.