Common Knowledge as a Barrier to Negotiation

When we communicate one thing, we often unavoidably send other messages. To start with a simple example, imagine that Ian says to Barry, My mother\u27s name is Karen. From Ian\u27s communication, Barry learns more than just the underlying bit of information (mom\u27s name). The communication also lets Barry know that: (a) Ian knows his mom\u27s name, and (b) Ian knows that Barry knows Ian\u27s mom\u27s name. What is less well understood is that when we teach, we learn. When Ian tells Barry about his mom, Ian learns several things