Some of noted Gandhi-style pacifist protest works better with some groups than others. If you are protesting against a group that thinks its wrong to kill unarmed protesters you’re more likely to survive than if, as in Myanmar, you go up against people who just kill any opposition that gets in the way.
Some might consider this an effective argument against pacifism. If pacifism is put forth because it works better than violence or force, then yes, such an argument would have force. But at least some of the pacifists I know consider pacifism to be right regardless of whether it works or not.
Bandits No More 
Amen, Brother! (I mean that literally)
Pacifism, at least Christian Pacifism, is based on Jesus’ life. As such it ought always be in touch with the truth that the practice thereof might actually get the practioner the same fate as it got Jesus – death at the hands of the violent.
Yeah.. words such as ‘effective’ and ‘productive’ don’t alwayes find themselves in a discussion of Christian Pacifism. I have to confess I aspire to be a Christian pacifist.. but at times want to also be effective and productive..
Isn’t better to say we are repositioning the stage on which we judge “effectiveness”?
The late Mennonite theologian, John Howard Yoder, argued that the effectiveness argument was not convincing for those who took a Just War position, because as he noted the obvious, but often unrealized truth, that in war violence fails 50% of the time.
The problem is that our culture worships at the altar of effectiveness. When we’re violent, we FEEL like we’re doing something, like we’re making something happen, like we’re being effective. When we’re non-violent, non-retaliatory, we feel – passive. Occasionally we remember the connection between passive, passion, and suffering.
And to the culture outside of the church, nothing looks more passive (and ineffective) than prayer. But we know the falacy in that…
I’d also mention that pacifism is not limited to the method of Gandhi-style pacifist protest. There are tons of ways to approach different types of conflict that work for an end of violence. The only commitment of pacifism is to renounce killing as one of those means. As far as effectiveness goes, I think that once we renounce lethal violence it is our obligation to seek to find active and effective ways of ending violence.