(Meditation 1- Descartes Doubts His Senses)Descartes reflecting on the number of falsehoods he has believed during his life and on the subsequent faultiness of the body of knowledge he has built up from these falsehoods. He has resolved to sweep away all he thinks he knows and to start again from the foundations, building up his knowledge once more on more certain grounds. Rather than doubt every one of his opinions individually, he reasons that he might cast them all into doubt if he can doubt the foundations and basic principles upon which his opinions are founded. What he learned is through senses. But they can be deceived. Use dream example. Convinced objects in dream are real. Dream images are drawn from waking experience. Meditator concludes, though he can doubt composite things, he cannot doubt the simple and universal parts from which they are constructed like shape, quantity, size, time, etc. While we can doubt studies based on composite things, like medicine, astronomy, or physics, he concludes that we cannot doubt studies based on simple things, like arithmetic and geometry. Simple things can be doubted. God would not deceive. It is an evil demon’s work
(Meditation 2- cogito ergo sum and sum res cogitans)He recalls Archimedes' famous saying that he could shift the entire earth given one immovable point: similarly, he hopes to achieve great things if he can be certain of just one thing. Recalling the previous meditation, he supposes that what he sees does not exist, that his memory is faulty, that he has no senses and no body, that extension, movement and place are mistaken notions. Perhaps, he remarks, the only certain thing remaining is that there is no certainty. Then, he wonders, is not he, the source of these meditations, not something? He has conceded that he has no senses and no body, but does that mean he cannot exist either? He has also noted