What fundamental assumption about human motivation is challenged by employing interest-based negotiation?

Employing interest-based negotiation challenges the fundamental assumption that human motivation is primarily driven by fixed positions and a desire to 'win' at the expense of others. Traditional negotiation often focuses on positional bargaining, where each party takes a specific stance or demand ('position') and argues for it, leading to a win-lose scenario. Interest-based negotiation, however, operates on the premise that underlying human needs, desires, concerns, and values ('interests') are more fundamental drivers of behavior. It assumes that by understanding and addressing these underlying interests, parties can find mutually beneficial solutions that satisfy everyone's needs, rather than simply compromising on stated positions. This approach challenges the assumption that conflict is inherently a zero-sum game and that individuals are solely motivated by self-interest and a need to dominate the negotiation process. For example, instead of simply arguing over the price of a product (a position), interest-based negotiation would explore why each party wants that particular price, revealing underlying interests such as maximizing profit, maintaining quality, or ensuring long-term supply relationships. Addressing these underlying interests can lead to creative solutions that were not apparent when only focusing on the initial positions.