Default Reasoning as Likelihood Reasoning

Book One

Volume

Proceedings of the AAAI Conference on Artificial Intelligence, 3

Knowledge Representation and Problem Solving

Several attempts to define formal logics for some type of default reasoning have been made. All of these logics share the property that in any given state, a proposition p is either held to be true, it is held to be false, or no belief about it is held. But, if we ask what default reasoning really is, we see that it is form of likelihood reasoning. The goal of this paper is to show that if default reasoning is treated as likelihood reasoning (similar to that of Mycin), then natural solutions emerge for several of the problems that are encountered when default reasoning is used. This is shown by presenting 7 such problems and showing how they are solved.