General alternatives:
* Premises
* Postulates
* Principles
* Tenets
* Beliefs
* Presuppositions
* Axioms
* Foundations
* Underlying assumptions
* Starting points
More specific alternatives:
* Epistemological assumptions (relating to knowledge)
* Ontological assumptions (relating to being)
* Moral assumptions (relating to ethics)
* Metaphysical assumptions (relating to the nature of reality)
* Logical assumptions (relating to reasoning and argumentation)
The best choice will depend on the specific meaning you want to convey and the context of your writing.