I watched "The Iron Giant" with my son today.
He'd already seen it, and I could go into this whole tirade about the grandparents letting my three year old watch a PG movie without asking us, but...eh, what the hell. I'm not overly concerned with violence and kids because I'm not a believer in the purity and sanctity of the minds of our youth. It means more work for me explaining to him why the giant robot was shooting guns, but whatever: I have to pick my battles.
SPOILERS: (Though the movie came out ten years ago, so I shouldn't really have to warn anyone.)
So the giant robot really was an "evil" alien construct sent to kill all humanity. Or at least destroy anyone that shoots at it. Though I briefly touched on this before, I think that it's a fair assumption that anything resembling life as we know it would be adequately capable of defending itself. Porcupines have quills and roses have thorns for a reason. Lots of things have the ability to run really fast, and its not to win a medal in a race.
Pacifism at its extreme form is unheard of in the animal kingdom, and is not a viable long term survival trait. The only reason why we toy with it as humans is for relationships with other humans (and for some people, animals with human characteristics, like rabbits and seals. You don't see many people campaigning to cease the cultivation of wheat, for example, despite the fact that the wheat is probably at least a little discontent whenever harvest time comes around.)
Apparently though, in the universe of "The Iron Giant", consciousness gives beings the capacity for nonviolence. Though the robot has one major advantage: it eats nonliving metallic objects for sustenance. It doesn't need to ingest other lifeforms to survive, unlike humans, who are technically parasites. (Agent Smith is right, Mr. Anderson!)
What would a photosynthetic plant-like alien life form think of us as we continually conquer all earthly foliage and shape it to our whims? Will they see us as cruel taskmasters, who keep soybeans and corn in bondage?
What would an intelligent single cell alien life form think of vaccines and antibiotics? How would a bug-like life form react when they found out about Raid?
Our consciousness cannot unshackle us from the constraints of our physical form. We cause other beings harm with and without our consent. The happy lie is that plants and bacteria and flies don't have feelings or consciousness, which is absolutely unprovable. No one has any idea what a cockroach thinks about in its tiny little brain as my three year old squishes it into the sidewalk. I'm not saying that their awareness is as advanced as ours, I'm saying that they might have a simple awareness, which is still awareness, regardless of complexity.
How would we react to an advanced alien civilization, a million years advanced from our own, that decides, "Bah, these creatures called humans can't be conscious (because they aren't as evolutionarily advanced as us) so let's squish them. Who cares? They can't be aware of their demise, so whatever. Drop the graviton bombs and lets clear the place."
It's why a part of me dreads the day SETI hears something: I'm not sure whoever's talking is friendly.