> if both parties "won" then didn't both ultimately lose? No, because even in a capitalist society "winning" is defined by each party's relative improvement ov

> if both parties "won" then didn't both ultimately lose? No, because even in a capitalist society "winning" is defined by each party's relative improvement over the state they would be in if they didn't come to an agreement and make the trade—not by some absolute measure of whether they did better than the other party. A "win-win" is simply an agreement where both parties are better off for making the trade. This is the usual state of things when both parties are free to accept or decline and there is no deception (fraud) involved, since both parties need to accept the agreement and they will only do so if they believe that doing so benefits them. In rare cases one or both parties may be mistaken about the benefit, but they know their own business better than anyone else and are best positioned to judge the expected value of making the trade based on the information available at the time.