Radical doubt
If there is any doubt in a statement, then the statement is false
Descartes questions
What can be know with 100% certainty
Foundations of his beliefs
Senses
Reasoning
Axiom/self evident truth
I think, therefore I am
Premise
God exists as the infinitely good and perfect being
Conclusion
The external, material world exists
Principle
God put the idea of himself into our minds
External/material world
WhAt one sees is what is out there
If you see something else, that is your fault
Deductive argumentation
Moves from a known principle to an unknown truth