In is third meditation, Descartes reiterated that having an idea of the existence of God is a confirmation of the existence of God. In essence, the main message of his argument in Meditation III is that the innate idea of the existence of God is a confirmation of the existence of a being (God) who is infinite, all-knowing and all-powerful. In the argument, Descartes tries to prove that God exists through the fact that he (Descartes) has in himself the essence of God, the idea of God. In relation to causal phenomenon, Descartes shows that there might have been an infinite force (God), who instilled the idea he harbors in him. He agrees that a human like him is finite, and doubtful because he is not the originator of his essence, but the cause of his existence controls him and makes him doubtful. In the same way that Descartes argues the existence of God through the possession of an idea about his existence, the existence of an evil demon can be proved trough the theory of existence of an idea about the same. In essence, alluding from Descartes’ Meditation III, that the idea of God proves his existence, it is arguably true that the idea of an evil demon is the essence of its existence.

Descartes’ argument about the existence of God revolves around his (God) being the cause of Descartes’ doubt, existence, and limitation in thinking. Indeed, Descartes tailors his argument to point towards the understanding that  his nature as a ‘thinking thing’ has an infinite cause, which is God. In his support of the existence of God, Descartes reiterates that people’s ideas have three distinct sources, whereby they can be a creation of oneself, acquired or innate. Further, as Descartes goes ahead to support the innate idea as a confirmation of the existence of God, he argues that the different ideas are representations of different things. Such specific representation becomes the reality of that particular idea, which eventually defines its origin. On the same line, the representations of the different ideas are different, which is a pointer that they must have different origins. As such, the perceived representative reality of a particular idea is defined by the ideas’ intrinsic origin or reality of the object that bore the idea. According to Descartes, there are those ideas that one cannot doubt their existence because they are inscribed inwardly. He argues thus: “From whom then…..could I derive my existence? (1639, 29).”Such is the idea of God, which leads to Descartes’ conclusion that God is absolute.

Descartes further supports his argument of the existence through the possession of an idea by explaining the reasons for doubt and desires. In his explanation for doubts and desires, Descartes first agrees that a human being is a limited being; a lacking being. Indeed, he connotes that human beings experience doubts and desires because there are those elements they lack, and they do not have a way of fulfilling them in full measure. According to Descartes, only God, who is infinite, all-knowing and all-powerful, possesses the things that human beings lack, and humans cannot access those things unless through the understanding of the existence of such a powerful being that possesses them. As such, Descartes says that he cannot doubt the existence of God because he has a very clear instinct (idea) of his existence.

In the same way the existence of an idea about God proves his existence, the idea of an evil demon connotes its existence. Borrowing from his explanation about the origins of ideas, it is clear that Descartes shows that the idea of an evil demon originates innately, just like the idea of God. He argues thus: “If God did not in reality exist…..who could be in my mind? (1639, 38).” Such an argument can be interpreted to  mean that the existence of an innate idea about an evil demon proves its existence, just as the innate idea of God’s existence proved the same. Indeed, Descartes argued clearly that the essence of an evil demon was innate, and it produced a more representative reality. Just as the innate idea of God in human beings proves an origin, which is God, the mere fact of an innate existence of the evil demon idea is a confirmation that it exists.

The idea of the evil demon, however, differs from the idea of God. According to Descartes (1639), the idea of God is innate. On the other hand, doubts and desires can lead to the creation of the idea of evil demons, rendering the idea ‘non-innate,’ which would then discredit the evil demon’s existence. On the other hand, the similarity is very vivid. While the existence of God is the source of the innate idea about God, then the existence of an evil demon is the origin of the innate idea about the evil demon. In that sense, the idea of an evil demon proves its existence.

In sum, Descartes proves the existence of God by arguing through the existence of an innate idea about God. He reiterates that the innate idea of God has a representative reality, which points to an infinite origin, proof that God exists, is non-deceiving and is all-powerful. In the same line of thought, the existence of an innate idea about the evil demon proves its existence. While, the innateness of the evil demon idea can be limited through human doubt and desires, the similarity is very vivid, pointing out that the existence of an innate idea about an evil demon is a true representation of its existence.

Reference

Descartes, R. (1639). Descartes and the problems of skepticism: Meditations

on First Philosophy. Retrieved from: http://www.uri.edu/students/szunjic/philos/med1.htm