Abstract: With the development of modern natural sciences and the comedown of traditional humanities, the foundation of Geisteswissenschaften was put on the agenda. Whether the Geisteswissenschaften / human sciences have their own logic or methodology, has been a crucial philosophical issue since the second half of the 19th century and is still of great concern in the contemporary academic context. Vico was the first to lay a foundation for human sciences by elucidating the legitimacy of humanistic knowledge in terms of the poetic logic; nevertheless, he confused “genesis” with “validity”. Dilthey developed methodologies of descriptive psychology and hermeneutics further, which was a critical step in founding and justifying Geisteswissenschaften, but he was still confined to the traditional epistemology. The intrinsic connection between understanding and Geisteswissenschaften wasn’t revealed until Gadamer demonstrated in his philosophical hermeneutics the dialogue-structure of understanding and the “logic of question and answer” of the Geisteswissenschaften. In this logic, however, a kind of epistemological and practical relativism could arise in that it is mainly restricted to the ontological description. This paper, through investigating the historical development and the logical foundation of modern human sciences / Geisteswissenschaften, aims to propose a “dialogic” in which the ontological and epistemological-methodological dimensions are interconnected on a higher level. This kind of dialogic, while integrating such elements as interactivity, critical reflection, openness and ethicality, could not only constitute the key characteristic of the Geisteswissenschaften but also facilitate comprehensive cross-subject research.