A principle can be a precept, rationale, or rule.
(The plural principles has a more specific connotation, that being the rules or precepts by which someone lives; as in having good ones.)
A synonym for the word doctrine is belief or principle.
belief, opinion, principle, research
mentality, mindset, mind
method, plan, policy, rule, principle, procedure, recipe, blueprint
standard, test, rule, measure, principle, gauge, yardstick, touchstone
Honor, uprightness, candor, forthrightness, principle, virtue, incorruptibility.
belief, view, opinion, principle, faith, persuasion, creed, tenet, certainty, confidence, assurance, firmness, certitude
teaching, principle, belief, opinion, conviction, creed, dogma, tenet
A synonym for "basic truth" is "fundamental reality." Other alternatives include "core principle" and "essential fact." These terms convey the idea of a foundational or inherent truth that underpins other concepts or beliefs.
There are several different synonyms for the word axiom. Some of these include accepted truth, general truth, dictum, truism, and principle.
Not sure about synonym, but Isaac Newton called it the Great Principle of Similitude.
speak, say, utter, read out command, order, decree, demand, direction, fiat, edict principle, law, rule, standard, code, criterion, maxim