We propose a novel knowledge representation method for the Default Logic paradigm by developing a proof calculus that yields arguments and counter-arguments in which defaults serve as explicit objects of reasoning. The proposed formalism allows for more transparent default reasoning and the use of explain-ability methods in formal argumentation. In particular, we provide a sound and complete argumentative characterization of Default Logic, by demonstrating that argumentation frameworks instantiated by the arguments derivable in our calculus yields the same inference relation as that of Default Logic. The modularity of our approach allows for various modifications of Default Logic. We demonstrate this by extending our calculus with a rule that enables disjunctive defeasible reasoning.