Ladies and gentlemen of the forum, I would like to present for your consideration, the following situation:
You and your tribe live on an Island with three other tribes,
The Yellow tribe is universally placid, peaceful and innocent. Each Yellow provides for themselves and is entirely self-sufficent. They have no concept of warfare or property, and they never fight or steal from anyone, within their tribe or without. The Green tribe, rather than providing for themselves, kill and dismember members of the Yellow tribe, eating their flesh, drinking their blood and building their homes from the bones and skin of the Yellows. The Red tribe takes this cannibalism a step further: they kill members of all tribes, Yellow, Red or Green, and, if not for your own incredible strength, would certainly try to kill and eat you as well. There is no food on the island except for that which the Yellow Tribe manages to grow, but they are willing to share what they can spare with the other tribes. Many members of your tribe, the Blues, supliment this diet with the meat of the others, just as the Reds do. Others, feeling themselves more moral, restrict themselves only to eating the Yellows, sparing both Red and Green. It is taboo for a Blue to eat another Blue, and it is considered strange for a Blue to refuse to eat a Yellow.
Many say that it is the will of God, or the way of Nature for the Yellows to be eaten. Others claim that the Yellows are too stupid to be worth shedding tears over, too stupid to feel pain or fear for their lives when their killers come. It is said that the Yellows don't have souls. The Yellows hardly put up more than a token resistance to being killed, so they must not object too much. All convincing arguements, so the choice is clear: Eat as you wish, sparing the Greens and Reds if such suits you, or not if it suits you not to, but feast upon the Yellows as much as you like, with neither guilt nor pause!
The Yellows, as you may have guessed here, are plants. The Greens are herbivores and the Reds are carnivores. Blue is man and the Island is Earth. How do you sleep at night, oh eater of the innocent, whose teeth have torn apart a thousand upon a thousand upon a thousand living beings? Does your conscience even give you pause as you rip and tear, feasting upon the boiled infants of the world's vegetation? I didn't think so. You monster.