Talk:Introduction to Philosophy/Rationalism

Descartes didn't find much truth throughout his entire life. In fact, the only things he really accepted were 1) The fact that he existed (Cogito ergo sum - I think, therefore I am), 2) Reason/logic, 3) Math, and 4) Theological dogma (he was a devout christian).

When he was trying to find truth in something, he was always looking for it to have as much certainly as mathematics; math is ALWAYS the same, regardless of whether or not we're in a dream. That is, you cannot be dreaming and trust in anything except the fact that you exist and 2+2=4. 2+2 is always 4 and a triangle is always a three sided shape whose interior angles add up to 180 degrees.