I wrote before that doing evil to create good has an inherent flaw: the certainty of the evil has to be balanced against the uncertainty of the good.
I realize now that I left out the greatest flaw. If we accept evil as a means to good, we validate evil. And to validate evil is to give it strength.
Can we really strengthen and validate evil, and at the same time say that we do so in the name of good?
Does good really mean any means to an end?