Balancing Rationality and Utility in Logic-Based Argumentation with Classical Logic Sentences and Belief Contraction

Compared to abstract argumentation theory which encapsulates the exact nature of arguments, logic-based argumentation is more specific and represents arguments in formal logic. One significant advantage of logic-based argumentation over abstract argumentation is that it can directly benefit from logical properties such as logical consistency, promoting adherence of an argumentation framework to rational principles. On the other hand, a logical argumentation framework based on classical logic has been also reported of its less-than-desirable utility. In this work we show a way of enhancing utility without sacrificing so much of rationality. We propose a rational argumentation framework with just classical logic sentences and a belief contraction operation. Despite its minimalistic appearance, this framework can characterise attack strengths, allowing us to facilitate coalition profitability and formability semantics we previously defined for abstract argumentation.