tenet

precept, principle, rule, standard

assumption, given, hypothetical, if, postulate, premise (also premiss), presumption, presupposition, supposition

hypothesis, proposition, theory, thesis

axiom, maxim, truism, verity

belief, canon, doctrine, dogma, gospel, law

basis, foundation, ground

conclusion, deduction, inference

affirmation, assertion, avouchment, declaration

dictum, ipse dixit