Rene Descartes (1596-1650) was not only a philosopher but also a mathematician and scientist. As a philosopher, he used skepticism as a means of finding the truth of all. His idea was to doubt everything, and in doubting everything, anything that couldn't be doubted was definite.
"I will doubt everything that can possibly be doubted, he reasons, and if anything is left, then it will be absolutely certain." (Moore/Bruder 93) This, Descartes felt was the only way to obtain truth and knowledge. This method was to take away all the confidence in everything that was taught to us, what we sense and believe, and the things we take as being obvious. To truly determine if we know anything is for certain we must doubt it all disregarding all we knew about it before. So everything we currently believe is open to discussion and can be questioned.
Descartes' 'Method of Doubt' incorporated two well-known conjectures, a dream conjecture and the evil demon conjecture. …
