richlind33: I oppose it for the same reason that I oppose polling: you present people with a dichotomy and say choose, but dichotomies are human constructs that only have relevance in contolled environments. Their function is to control how and what people think, the goal being a perfect state of "unthinking".
"Necessary evil" is a logical fallacy because that which is truly necessary is *not* an evil. I defy anyone here to come up with an evil that is truly necessary. You won't do it, because evil relates exclusively to satisfying one's desires, and unlike needs, desires are not necessities.
This does make for an interesting discussion. I disagree with your objection to polling, because you ascribe malice and the motive of controlling the polled to it - which can be true, but you assume it in all cases. Polling can be a legitimate attempt to obtain feedback on the opinion of a group around a certain decision - yes, it is necessarily imperfect, but the fact we can't do something perfectly is a very weak argument against doing it at all. And it certainly isn't evidence for sinister motivation, that's coming from somewhere else. Example: I've been polled on whether or not my city should make a bid to host the Olympics. Those commissioning the poll have to make a yes or no decision on whether to proceed. Of course there are a myriad of other things they could be working on, but this is the particular decision currently in question. Ideally (assuming one wants a democratic decision), they would gather a subtle, complete picture of every citizen's complete views on the subject, and apply that to the decision-making process. In reality that is impossible, and not because of artificially-induced limitations, but because of real ones.
I'll take a stab at the "necessary evil", though I see you have already defined it into impossibility by claiming the truly necessary is therefore not evil. But here, anyway... I'm curious to see if you consider survival a necessity, or a desire: two people trapped in some isolated situation (deserted island, whatever) with no independent means of escape. Rescue is possible but unpredictable. Water is available, but food is not. We have waited to the point where death by starvation is imminent. I have a knife, and can kill and eat my companion to prolong my survival, somewhat shortening his - he refuses to sacrifice himself voluntarily. If I do not kill him, we will most likely both die with a day or two - and before the end I will become too weak to kill him. If I do kill him, I can last... let's say three more weeks. Is killing him not a necessary evil?
For a complex variant, I have my young daughter with me as well. She is weaker - I could sacrifice myself, but I know that when starvation strikes again, if it does, he will kill her. Or I could kill him now, feed the two of us for a time, and sacrifice myself when necessary..
If your argument that my preference for my own survival (or my daughter's) over a stranger's is merely "desire" and not "necessity", then you have defined necessity into meaninglessness. If you claim that killing the stranger for food is not evil... then I think you're working with an idiosyncratic definition of evil. But sure, then using your definitions, of course there's no such thing as necessary evil, that position would be tautological. It just has no relation to how most people use the term.