I agree, I'm not sure I like the question.
Pacifism has worked for different people groups in various times. For the early church it was their refusal to fight back against a ruthless Roman Empire that drew people towards the religion. Christians were mocked, spit on, burned alive as torches and butchered by animals, yet refused to fight back. Is that pacifism or simply non-violence?
But it was pacifism for a cause, in this case the cause of Christ. Would these same people have remained pacifists, or would I, if they were mocked, tortured, and burned for funny hats or ugly beards? Probably not.
I think MLK realized that to draw-out the mercy of the common white people toward racial equality, the best option was to simply not fight back. Malcolm X's strategy just didn't work, and I for one think it's still a hurdle some white people have to get over, to rid themselves of racism. No one likes a minority or "different" kind of people raising up to fight the dominant one.
Now, if we're talking nation-building than perhaps that convo belongs in a poli-sci class.
The question just needs defining. Pacifism definately can and does work in relationships between individuals, I feel like that much is obvious. Would you rather date/marry/befriend someone that punches you in the nose everytime you say something that hurts their feelings or would you rather date/marry/befriend someone that would show patience and grace and mercy to you, even though they are hurt?