The phrase "based on theory" can be replaced with a variety of synonyms depending on the context in which it is used. Some alternatives include "theoretical," "hypothesized," "speculative," "conceptual," "abstract," and "intellectual." Each of these terms conveys the idea that something is grounded in ideas or principles rather than being observed or proven through empirical evidence. Other phrases that might be used to replace "based on theory" include "ideological," "philosophical," "theoretically-driven," "speculatively-based," and "conceptually-influenced." Depending on the context, writers may choose to use one of these synonyms or a combination of several to convey the meaning that best suits their message.