Reasoning and modeling paradigms are incompatible

Object-oriented and logic-programming paradigms are shown to be incompatible as component-based models of computation. This impossibility result, based on a new notion of observability of interactions among components, suggests that combining object-oriented with logic programming is not merely hard but impossible. It implies the more general incompatibility of reasoning and modeling and the impossibility of reducing modeling to reasoning as in automatic program verification. While paradigmatic incompatibility is the most startling result, the novel use of models and metrics is of independent interest. A notion of software complexity with parallels to computational complexity, and a notion of LP-completeness that parallels NP-completeness are introduced