Hybrid Logics for Arguments, Beliefs, and their Dynamics Max Rapp Abstract: We study abstract argumentation, argument based belief and their dynamics in the setting of Hybrid logic. For this purpose, we develop Hybrid Argumentation Logic (HAL), a logic optimized to express the concepts of abstract argumentation theory. Combining HAL, a theory of support between arguments and propositions, and a logic for the claims of arguments in a product logic, we study three notions of argument based belief that reflect ways in which agents might form beliefs from arguments: credulous belief, skeptical belief and strong belief. In addition, two update operations for abstract argumentation frameworks are introduced and studied: argumentation framework union and argumentation framework intersection. These serve as semantics for two dynamic modal operators for HAL, yielding the logic HAL∩∪. It is shown that HAL∩∪ is at least as expressive as first-order logic and hence undecidable. We then study how argumentation framework union affects credulous, skeptical and strong belief respectively and find that they have different dynamic properties. In addition we provide sufficient conditions for preservation of belief under argumentation framework union.