Never Split the Difference: Negotiating as if Your Life Depended on It

by Chris Voss

I was employing what had become one of the FBI’s most potent negotiating tools: the open-ended question.

we call this tactic calibrated questions: queries that the other side can respond to but that have no fixed answers. It buys you time. It gives your counterpart the illusion of control—they are the one with the answers and power after all—and it does all that without giving them any idea of how constrained they are by it.