self-consistent = contains no valid proposition that can prove true and prove false under the same theory 1. Does a physical theory need to be self-consistent? Why? 2. Is it possible to accept a theory that agree with all facts but contain inconsistencies? 3. Is a self-consistent theory better than inconsistent one? (I think that Feyerabend's arguments seem to contain a lot of fallacies. But I stuck on this one.) It is possible to construct a mathematical theory that is inconsistent. e.g. a theory that can talk about its own consistency. What about Physics and Science? This is not the same case to inconsistency between QM and GR. I'm talking about the inconsistency within the same theory.