a.k.a. common sense
The more I talk to people from different backgrounds and origins, the more I realize the importance of "thinking before you speak."
If we think about it, it's an incredibly fundamental concept that we are taught very early in life. However, the more people you see the more you can realize how undeveloped many people's tact is.
The problem is humans have and will always have certain fundamental differences, and our ability to approach these nuances with care shows our degree of self-worth, -respect, and -understanding.
I believe that most arguments and petty discords happen mainly owing to the deficiency of this exact trait among the counterparts, and arguments are fundamentally impractical, that is to say they don't lead anywhere but emotional complications.
Essentially, if common sense would actually be common, people would live healthier and more fulfilling lives.