in a way that is connected with the ideas and principles on which a particular subject is based, rather than with practice and experiment 理论上的 theoretically sound conclusions 理论上无懈可击的结论 These views were challenged both theoretically and empirically. 这些观点在理论上和经验上都受到了挑战。
in a way that could possibly exist, happen or be true, although this is unlikely 理论上存在的;假设的