Have you ever had a one-sided argument? It can't be done. If someone wants to have an argument with you and you don't participate, then there is no argument. Your opponents will try and push every hot button you have.
At first they will be confused. When they realize that you're there as an observer and not a participant, they may double their efforts to draw you into combat.
Their ego greatly fears your nonparticipation because it constitutes a loss of control. If your opponent were to start observing, then his ego would cease to exist, too."
(From Beyond Happiness: Finding and Fulfilling Your Deepest Desire, by Frank J. Kinslow)