An implemented AI reasoning system called ATT-Meta is sketched. It addresses not only AI issues but also ones that are salient in psychology, philosophy, cognitive linguistics, discourse pragmatics and other disciplines. These issues include the Simulation-Theory/Theory-Theory debate and Fauconnier and Turner's notion of concepmal blending. The system performs metaphor-based reasoning and reasoning about mental states of agents; in particular, it performs metaphor-based reasoning about mental states. Although it relies on built-in knowledge of specific conceptual metaphors, it is flexible in allowing novel discourse manifestations of those metaphors. The metaphorical reasoning and mental-state reasoning facilities are fully integrated into a general framework for uncertain reasoning. A special result of the overall approach is that it enables a unified handling of certain apparently separate discourse phenomena: chained metaphor, personification metaphor, and reports of agents' own metaphorical thoughts.

An unprecedented combination of simulative and metaphor-based reasoning about beliefs is achieved in an AI system, ATT-Meta. Much mundane discourse about beliefs uses conceptusJ metaphors (e.g., MINDAS CONTAINER ) productively, and ATT - Meta's metaphor-based reasoning accordingly leads to crucial discourse comprehension decisions. ATT-Meta's non-metaphorical mode of belief reasoning includes simulative reasoning (SR). In ATT-Meta, metaphor-based reasoning can block and otherwise influence the course of SR. Also, ATT-Meta can nest SR and metaphorbased reasoning within themselves and each other. As well as currently allowing ATT-Meta to simulatively reason about beliefs about beliefs ..., the nesting will in the near future allow the system to handle chained metaphors, ascribe its own metaphor-based reasoning to other agents, and apply simulative reasoning to purely metaphorical agents.