No theorem can be proved without using the statements which are taken for granted.

One word substitute is Postulates.

Maxims: a short, pithy statement expressing a general truth or rule of conduct.
Tenets: a principle or belief, especially one of the main principles of a religion or philosophy.
Postulates: suggest or assume the existence, fact, or truth of (something) as a basis for reasoning, discussion, or belief.
Stipulation: a condition or requirement that is specified or demanded as part of an agreement.