A negotiator should understand what the other side fears losing.

People negotiate hardest around what they are afraid of losing, which is often not the item under discussion. It may be standing with a colleague, a precedent, the appearance of having been outmaneuvered, or a risk they cannot afford to carry. Understanding that fear tells you where the real resistance is and how to remove it. Arguing with the stated position leaves it untouched.

Ask yourself what the other side would find hardest to explain to their own people. Then look for a way to protect them from that. Removing someone’s fear is often cheaper than meeting their demand.