Epistemology - the study of belief; the theory of knowledge
the three usual brances are as follows
Rationalism: essentially, logic and reason is superior, we must analyze everything logically, scientifically, etc.
Empiricism: we know things through what we sense; i.e, knowledge comes through input
Existentialism: there is no meaning, nothing is real, you define meaning
...why the heck do I have 6134 rep? anyways...