Man, this thread is disheartening. All the same non-logical arguments in favor of eating meat. "It's natural!" "They'd do it to us if they got the chance!" "Sentimental hippy bullshit!" "Top of the food chain rah rah!"
Look, it's simple utilitarian ethics. It's wrong to cause pain or to violate the desires of other beings without necessary cause. I would actually agree that, for most of human history, eating meat was *not* unethical. It was necessary for us to survive, and between the life of a cow and the life of a human, the human is more important because of their increased capacity for emotions and envisioning their own future. Likewise, If you're stranded on a desert island and your best odds at survival are to kill a wild boar- go for it.
But most people today are not in those situations. Eating meat is not necessary for most people in the Western world today. It doesn't matter if it's "natural" or we're omnivores or whatever evolution enabled us to do. It's bad when a creature with a desire to survive has it's life taken from it, and it's wrong to cause something like that without good cause. There is good cause to eat meat in times of survival, when it's either us or them. But it isn't us or them.
Even if we solve all the issues with factory farming and kill the animals as "humanely" as possible, it would still be wrong because ultimately, we are killing only for pleasure; to satiate our tastebuds. Animals like cows feel emotions, they form friendships and maternal bonds, they have an inherent instinct and desire to stay alive.
How can it be wrong to pointlessly kill a human but not an animal? It's not AS wrong, considering a humans stronger desire for life and conscious knowledge of what death is and to plan for their future...but it's still wrong on some level. It's crazy peopel are saying "factory farming is messed up, but I have no objections to killing my own meat!" Really? What need do you have to go kill some animal for no other reason because you enjoy how it tastes? You killing that animal did not save your life. It only brought you pleasure. Taking a life from something that wants to stay alive, only for pleasure- that's wrong.