Rene Descartes was one of the greatest philosophers in the Baroque period. He was influential not only in physics, natural sciences, mathematics, but most importantly his work on philosophy.
His way of thinking may be skeptical and doubtful, he is one of the European thinker included Thomas Hobbes and John Locke. And his famous phrase which he put in his second Meditation is “Cogito, ergo sum” - “I think, therefore I am”. As Lawrence mentioned in the Culture and Values: “According to Descartes, the first essential in the search for truth was to make a fresh start by refusing to believe anything that could not be decisively proved to be true”.In order to do that, he proposed to doubt everything doubtable first and then move on once to find the certain. This means that whatever he doubt, he rejects, and only take fact that he can sure to be true. There is an example in the Culture and Values of Lawrence, “we look at the sun we see it as a very small disk, although the sun is really an immense globe.
We must be careful, therefore, not to assume that our perceptions are bound to be accurate”. There are a lot of things around us, but it is not easy to demonstrate them as a fact.