Negotiation arithmetic: adding and subtracting issues and parties

Students of international negotiations often examine strategic interactions among a given set of parties dealing with a specified group of issues. The issues and parties themselves are often choice variables whose ultimate configuration can have decisive effects on a bargain's outcome. Using a variety of international cases, I investigate the properties of several classes of moves that are intended to alter the issues and parties of an original negotiation. A unified approach to the analysis of such situations suggests numerous distinct means by which the “addition” or “subtraction” of issues can yield one-sided gains to the use of power; can yield joint gains that create or enhance a zone of possible agreement; and can reduce or destroy a zone of possible agreement. The effects of adding or subtracting parties are similarly analyzed. However, unintended complexity, unforeseen interrelationships, organizational considerations, transactions costs, and informational requirements may alter the analysis of such moves.