Descartes uses what is known as the ontological argument to demonstrate the existence of God. Saint Anselm, who lived in the 11th century, first formulated this type of arguments. It has since proved popular with many philosophers including René Descartes. Although ontological arguments have lost popularity among modern philosophers, there have been some recent attempts to revive them. Descartes' formulation is considered one of the best because it is simple and relatively easy to follow. It is also helpful when trying to understand Descartes to keep in mind that he talks about two types of existence. There is the normal everyday existence that we experience and a special kind of existence that he calls necessary existence. Necessary existence is something that our mind can impose on normal existence. Descartes' argument can be presented very simply as: (1) Clear and distinct ideas equal necessary existence. (2) God's perfection equals clear and distinct ideas. (3) Therefore, God's perfection is equivalent to necessary existence. What does Descartes mean when he talks about clear and distinct ideas? Clear and Distinct suggests that there is an enormous amount of evidence that cannot be denied or contradicted. Let's think about the two most essential properties of a triangle. First of all, to be a triangle it must have three sides. Secondly, the sum of all the angles of a triangle must equal 180 degrees. These two essential properties of a triangle must always be found together if we are to assert that triangles exist. One without the other is worthless when it comes to triangles. For Descartes this is an example of a clear and distinct idea. It is also an example of necessary existence. Exactly the same way God has two... halves of the card... imply existence. Saying that God exists is exactly like saying that trees exist. We are not any wiser regarding the characteristics of God or the characteristics of a tree. Descartes would no doubt agree with Kant that there is no conceptual difference between something actually existing and imagining the same thing existing. The idea of ​​a supreme being is the same whether we think of God as something in our mind or as something that exists totally independently. However, I'm sure Descartes would like to add that there are two degrees of existence. Kant only dealt with the existence that we all know. He assumes that this is the only existence we can know. Descartes would like to say that Kant did not do justice to the idea of ​​necessary existence. It seems that Descartes' ontological argument is based on this point.D. Macintosh 6/2/10