Chris Voss’s book is about negotiation. Based on a skill rooted in the real-life experiences of hostage negotiations. Nothing much can come with higher stakes than the lives of others.
We often take negotiating positions because they are easier, both to define and to understand, than the principles that underlie them. It’s often not even be the best position, just the one that we have chosen that will do well enough for now. Principled negotiations allow you to find the unexpected, better option, that nobody had even considered when the negotiations began.