Defusing emotional reactions
"You Are There" Technique. Rational arguments alone are not likely to be successful, especially since many people "feel" rather than "think," so you also need to deal with emotional responses. You may need to change the person's emotional responses along with his or her thoughts.
When dealing with a person who thinks violence is never the way to solve things, you may put the person (or his or her family) at a hypothetical crime scene and ask what he or she would like to have happen. For example, "Imagine your wife is in the parking lot at the supermarket and two men grab her. One holds a knife to her throat while the other tears her clothes off. I am a black belt, if I see this happening, what should I do?" Just let the person answer the questions and mentally walk through the scenario. Do not argue with the answers. You are planting seeds in the person's mind than may help change his or her emotional responses.
Power of Empathy. Another emotion-based approach that is often more successful is to respond sympathetically to the plight of the anti-violence person. Imagine for a moment how you would feel if you believed your neighbors and co-workers wanted to kill you and your family, and you could do nothing at all about it except to wait for the inevitable to occur. Not very pleasant, is it? This is the world in which opponents of self-defense live.
All of us have had times in our lives when we felt "different" and had to contend with hostile schoolmates, co- workers, etc. Therefore, we need to invoke our own compassion for these terrified people. It is essential that you sincerely feel some compassion and empathy; if you are glib or sarcastic, this will not work.