Drapkin, J.Miller, MichaelPerlis, D.In common sense reasoning it is important to be able to handle conflicting data. We discuss this issue specifically in the context of default reasoning. We contrast two choices: either to constantly monitor the reasoning system in an effort to preserve consistency, or to allow inconsistencies to arise and then (try to) restore a semblance of order. That these are computationally virtually the same is granted; but there are other rather important distinctions between them bearing on default reasoning.en-USTechnical Report