The average negotiators went in armed for battle, hardly picking note of any anticipated areas of agreement. The experts, in contrast, mapped out a series of dance steps they might be able to take with the other side, devoting more than a third of their planning comments to finding common ground.
As the negotiators started discussing options and making proposals, a second difference emerged. Most people think of arguments as being like pair of scales: the more reasons we can pile up on our side, the more swill tip the balance in our favor. Yet the experts did the exact opposite: They actually presented fewer reasons to support their case. They didn’t want to water down their best points. As Rackham put it, “A weak argument generally dilutes a strong one.”
The more reasons we put on the table, the easier it is for people to discard the shakiest one. Once they reject one of our justifications, they can easily dismiss our entire case. That happened regularly to the average negotiators: they brought too many different weapons to battle.