This conceptual article explores shared epistemic agency between humans and generative artificial intelligence (GenAI), emphasizing the need to foster active human epistemic agency through adaptive epistemic stances. We propose a framework incorporating epistemic stances in interactions with GenAI, drawing on Tsai's (2004) work to explore the reinforcing relationship between them. The article outlines how learners' epistemic stances affect their interaction with GenAI and suggests strategies for fostering critical engagement and inquiry. We assert that learners with adaptive epistemic stances benefit more from GenAI and that continuous interaction with GenAI can reshape learners' epistemic development. This article aims to promote a symbiotic relationship where both human and machine contributions are valued, ultimately enhancing the overall learning experience through shared epistemic agency.