With the growing interest in rule languages in the Semantic Web and the Business Rule community it is time to look again at the issue of debugging rule bases. New challenges have arisen since the time most concepts for today’s debuggers where created: end user programming has grown in importance, graphical editors have become more common and programs are increasingly interconnected. Today there is no debugger for rule-based systems that takes into account the declarative nature of rules and that addresses these challenges. This paper proposes Explorative Debugging as a paradigm for building debuggers that truly take into account the declarative nature of rules. The Inference Explorer is presented as an implementation of the explorative debugging ideas. 1 Keywords Rule-based systems, debugging, F-logic, explorative debugging