It comes down to the deep and universal human need for autonomy. People need to feel in control. When you preserve a persons autonomy by clearly giving them permission to say No to your ideas, the emotions calm, the effectiveness of the decisions go up, and the other party can really look at your proposal. Theyre allowed to hold it in their hands, to turn it around. And it gives you time to elaborate or pivot in order to convince your counterpart that the change youre proposing is more advantageous than the status quo.

Never Split the Difference by Chris Voss