How to deal with war supporters:
Explain to the war supporter that bombing terrorist countries won’t prevent terrorism, because violence does not persuade people to change their views. Explain that on the contrary, use of violence will make the terrorists angrier and lead to more terrorism.
Listen to the war supporter explain that we still have to go to war to stop terrorism.
Without any warning, punch the war supporter hard in the face.
As he gets up off the ground, ask him if he’s angry now. Wait for him to admit that yes, he’s furious.
As he nurses his broken nose, ask him if he is now convinced that you are quite right. He’ll say something to the effect of “no way”.
Point out to him that you have just demonstrated that violence makes the victim angry, does not persuade him to change his views, and hardens his opposition to you. QED.
Wait for the clue to penetrate his thick skull.