René Descartes (1596-1650) recognized that this influence of false beliefs could impair his scientific investigations, producing possible false conclusions to his thinking. Therefore, he "realized that it was necessary, once in the course of [my] life, to demolish everything completely and start again right from the foundations if [I] wanted to establish anything at all in the sciences that was stable and likely to last." Descartes began his philosophical career by trying to provide a sound basis for the new scientific method that was being developed, but at the same time he wished to show that this new scientific methodology was consistent with Christianity. It was because of this that Descartes began his Meditations on First Philosophy. Descartes' overarching goal in the Meditations can be viewed as "a search of a complete system of knowledge, in which [he] would prove the existence of God, understand the nature of the human mind, and establish the principle on which the material universe can be studied."
Descartes First Meditation: What Can be Called into Doubt is the first of the six total meditations. He opens this meditation by restating his desire to have only true beliefs. He proposes to systematically follow a process of skeptic doubt. His doubt is not one of simply common sense, though, for instance like I might doubt whether superstitions bring good luck. Instead, his doubting process is philosophical and exaggerated, in which the issue is whether a system of knowledge can be in any way doubted. The goal of his doubting process is to arrive at a list of beliefs that are absolutely certain. Descartes does not intend to doubt the truth of every specific conclusion that enters his head individually, which would be an impossible task, but rather to undermine "the basic principles (foundations) on which all my former beliefs rested." And that is what he set out to tackle in this First Meditation. By the end of these thoughts, Descartes arrives at his overall conclusion when he states, " I . . . am finally compelled to admit that there is not one of my former beliefs about which a doubt may not properly be raised . . ." In other words, there is reason to doubt everything he believes.
Beginning, as he had planned, with the foundation of his beliefs, Descartes first considered where the majority of his beliefs found their source. He quickly recognizes that whatever opinions he had accepted were either from or through the senses. However, he also knew that he had been deceived by his senses in the past, and for Descartes, this was reason for doubt. He begins doubting the reliability of his senses by noting in one case that we perceive distant objects to be much smaller that they really are, otherwise known as an optical illusion. His skeptical doubt at this point is considered "Stage 1 Doubt" and in other words, his class of sensory knowledge has been known to break down and therefore can never be absolutely trusted. In considering his physical attributes and the feeling of the environment which he also derives from his senses, he likened himself to a madman with a damaged brain, but then quickly disregarded that because he saw no point to argue had he really been mad.
Continuing his doubting experiment, Descartes suggests the possibility that he...