Say this when someone has a complaint or is critical, especially of your behavior. Even if you do not feel their opinion is 100% accurate, you could likely honestly concede there is some truth to it. Remember, we all have blind spots. Similarly, you could also use the phrase, "I could be wrong."
Sounds silly, I know. But really, if someone makes a particularly personal, hurtful comment, saying, "Ouch," is a great way to respond without attacking them back.
3. "I need some time to think about that."
If someone is asking you a question (or for permission) you don't want to answer in public, this is an ideal response. It buys time, is tactful, and helps the other person see they need to give you some space.
4. "What do you think about _________?"
Ask questions about the issue they are concerned about, use good eye contact, and rephrase back what they are saying to be sure you understand. Showing an interest in the other person's thoughts and opinions is often enough in itself to help diffuse arguments. When people feel heard--truly listened to--they are generally calmer.
5. "Let's Google it."
So many arguments can be solved by finding reliable information or research. Even if it is a relationship issue (or something opinion-based), professional opinions are all over the internet and can be helpful. And, by saying "let's" you remind the other person of your desire to work with them, rather than against.