1) Descartes uses a method commonly referred to as Methodical Doubt (beginning with a doubt in hopes of arriving at a given certitude). With this skepticism, Descartes questions the inherit nature of what it is to be. It is his initial perception, upon beginning his piece, again, with "methodical doubt", which the world may not exist, but may be a facet of an individual's imagination. However, he quickly contests this argument with his face phrase, "cogito ergo sum" which means "I think, therefore, I am"
I. The Arguments for Universal Doubt:
In order to show that science rested on firm foundations and that these foundations lay in the mind and not the senses, Descartes began by bringing into doubt all the beliefs that come to us from the senses. His aim in these arguments is not really to prove that nothing exists or that it is impossible for us to know if anything exists (he will prove that we can know external objects later), but to show that all our knowledge of these things through the senses is open to doubt. If our scientific knowledge came to us through the senses, we could not even be sure that anything outside of us existed. The obvious implication is that, since we do know that external objects exist, this knowledge cannot come to us through the senses, but through the mind.
Descartes uses three very similar arguments to open all our knowledge to doubt: The dream argument, the deceiving God argument, and the evil demon argument. The basis idea in each of these is that we never perceive external objects directly, but only through the contents of our own mind, the images the external objects produce in us. Since sense experience never puts us in contact with the objects themselves, but only with mental images, sense perception provides no cer ...