Descartes

            In Meditations on First Philosophy, Rene" Descartes discusses the existence of external objects, primarily in the First Meditation. Descartes doubts the existence of external objects based upon the idea that an "evil genius" exists instead of an ideally good God. This "evil genius" strives at deceiving Descartes. Descartes now assumes that all external objects- "the heavens, the air, the earth, colors, shapes, sounds"- are nothing more than hoaxes produced by the "evil genius" and therefore do not exist.
             At the end of the First Meditation, thinking and perception remains certain because your own thinking and perception is the only thing you can believe because it exists in your mind and not in the external world, which can be altered by things such as the "evil genius". .
             In discussing the existence of external objects, Descartes must also include the existence of God. The existence of God is based upon the "ontological argument". The ontological argument is that God is a "being than which none greater can be thought". The meaning of the argument is that the concept of God is the greatest being who can be thought, and therefore He must exist. .
             The counter argument is an argument against the ontological argument. It discusses that existence is an essential property and part of the definition of a thing, that is God. The counter argument says that existence is not a property and cannot be part of a definition.
             Descartes attempts to prove the existence of God and his own self. Descartes argues that God exists as the necessary thing that first caused all other causes in the world, but Descartes has not yet proved that there is a world. Descartes argues that we can only think of this idea of God because a real God exists whom makes it possible for us to have this idea of God himself. Descartes also argues that without God we would not exist because God causes things in this world to exist, that is ourselves and the idea of God's existence.