2 Some boundary conditions on embodied agents sharing a common world John Barresi 2.1 Introduction What are the conditions that make it possible that you and I share the same world? This is the issue on which I wish to focus this chapter. There are a number of such conditions, some of which I would call boundary conditions. For instance, if you and I were in dis- tant locations in space and time, it would be difficult for us to share a common world, even though conceptually, we might imagine that such a thing could exist for us. If you are outside of my light-cone, according to relativity theory, we cannot share a common world in any practical way. In order to share such a world we would need, at minimum, to have personal worlds that are within light-cone proximity to each other. This is an example of what I mean by a boundary condition on embodied agents shar- ing a common world. It is a necessary condition on any form of world sharing between embodied agents that they are in light-cone relationship to each other. This is a necessary condition because without it there could be no overlap in personal worlds between one embodied agent and another; and, without overlapping personal worlds, there could be no common world for the agents to share. Why am I asking the question of what are the boundary conditions for world sharing for embodied agents? I’m interested in the possibility of developing some common lan- guage to describe social relations between embodied agents of all kinds, from different species of animals, to humans, to robots. How can we describe their relations with each other in such a way that the language we use is general enough to cover all cases but affords differentiation? Searching for such a language may provide insight into basic principles of social life. Among the terms and their relations to each other that I will be discussing are communication, causation, embodied agent, information, purpose, signal, embodied communication, intentional relation, personal world, common world, and common ground. The hope is that by looking at these terms in this context, what might otherwise be lost in diverse terminological investigations of separate terms can be brought together within single overarching framework—one that I hope will be useful for reflecting on the diverse investigations undertaken in different chapters of this book. 02-Wachsmuth-Chap02 6/3/08 9:55 AM Page 29