張東蓀是我國當代重要的哲學家，特別是在知識論方面。他把知識區分為三個類型：敘述、說明和解釋；提出知識的機能為感覺、知覺、概念和條理，後二者可概括於知性中；更確定知識的要素為認知主體、認知對象和認知活動。他把認知理解為認知主體以其本身的格式來規範對象，復以對象來修正其格式。所以認知作用不專靠先天的格式，也不專靠後天的經驗，而是以先天的格式整理後天的經驗，更以後天的經驗証成先天的格式。他的立場是超越經驗主義和理性主義，師法康德的綜合主義，卻廢除後者的統覺作用，對後者的知識論作出理性的修正。張東蓀在知識論方面最大的貢獻，是把認知對象由滯礙的質體轉化為鬆動的架構，讓認知作用有較強的靈活性與較廣的活動空間。這一方面是接受了相對論和懷德海的機體主義的影響，也有他自己的洞見在裏頭。

This is a study of the epistemology of Chang Tung-sun, one of the most pivotal philosophers in Contemporary China. He divides knowledge into three types: descriptive, explanatory and interpretive, and takes the cognitive faculties as sensation, conception and order making, the last two being included in understanding. As regards the elements that form knowledge, he proposes cognizing subject, cognized object and cognition itself. He construes cognition as an activity in which the cognizing subject characterizes the cognized object with its own categories, and in turn the categories will be rectified by the cognized object. In consequence, cognition does not merely depend on a priori categories, nor merely depend on posterior experience. Rather, it is a cooperation of a priori categories and posterior experience. Epistemologically speaking, Chang transcends both rationalism and empiricism, and inclines toward Kant's synthetic standpoint, except that he relinquishes Kant's concept of transcendental apperception.Chang's most manifest contribution to epistemology is that he transforms the cognized object from the concept of a solid entity to the concept of a structure, thereby enhancing the flexibility of cognition and strengthening its validity.