Introduction

Abstract

The last few decades have witnessed the growing importance of multi-agent perspectives in epistemic matters. While traditional epistemology has largely centered on what single agents know, barring the occasional encounter with a skeptic, there has been a growing focus on interaction in many disciplines, turning from single-reasoner to many-reasoners problems, the way physicists turned to many-body constellations as the essence of nature. This trend may be seen in social epistemology, speaker-hearer views of meaning, dialogical foundations of logic, or multi-agent systems instead of single computing devices in computer science. While an inference or an observation may be the basic informational act for a single agent, think of a question plus answer as the unit of social communication. This agent exchange involves knowledge about facts and about others, and the information that flows and thus changes the current epistemic state of both agents in systematic ways. Existing epistemic and doxastic logics can describe part of this setting, since they allow for iteration for different agents, expressing thinks like “agent 1 believes that agent 2 knows whether the heater is on”. But the next level of social interaction involves the formation of groups with their own forms of knowledge, based perhaps on shared information.

Horacio Arló-Costa was deceased at the time of publication.