Clarity in Non-Monotonic Logic Harald Bastiaanse Abstract: It is telling that historically mathematics and even the sciences have often made great leaps forward by switching to new formalisms and paradigms in terms of which the phenomena under study were easier to express and comprehend. Evidently unclarity can stifle a field, or at least prevent readily available results from being picked up on when needed. In this thesis we will ascertain as much by looking into the field of non-monotonic logic. We take a look at a system for default rules that has great empirical adequacy but also no lack of complexity, and that has thus remained basically unnoticed for a long time. And exactly as our little theory suggests, a fruitful application presents itself immediately after we've rephrased the system to increase its clarity...