Wow... this thread is so... tangential.
As to the posts re: bugs and bacteria. That's actually a valid point. All organisms have "feelings" or emotions on some level. Emotions being defined as irrational reactions to environmental stimuli or perceived needs (fear, greed, joy, lust, etc). Who's to say that plants do not fear being cut down? Fish definitely feel fear. And pigs and cows (especially pigs, they're smarter than dogs) do feel fear, and do have a sense of self, so on facing death,
not only experience fear, but terror.
I think the moral question is: to what end?
If you're killing for sport or for fun, it's inhumane (technically), and, some
might argue, inhuman.
If you're killing for food, then it's humane? It's definitely human, and very VERY natural.
The concept of humane treatment is certainly
unique to humans. Chimps commit fratricide, and so do dogs and some other higher mammals. Lions and other predators commit fratricide and infanticide in territorial and authority squabbles.
Dolphins kill baby dolphins and porpoises for SPORT. Anyone else remember one video where a "playful" dolphin bit and dragged a swimmer down a couple dozen feet to almost certain asphyxiation? So when we're talking about killing as only being natural if it's for food, then that's hypocritical. Animals kill all the time, for all sorts of reasons.
As for cruelty to animals: Same as above, same example with dolphins. Chimps will beat rivals to death.... slowly. Cats "play" with mice before eating them, pack predators often hound prey to death before asphyxiating them. The quick kill is often a myth. But animals can also be strangely fraternal. Dogs and cats can often show a strange affection for creatures they'd usually consider as prey (chickens, ducks, etc.). Dolphins are very friendly towards humans, though aggressively and homicidally inclined against other big aquatic mammals (other dolphins and porpoises, seals, too)
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What our guide should be is the intentions and intended outcomes of the action. If we treat animals "cruelly" or "inhumanely" or kill them just for the heck of it, or with the
expressed intent of causing the creature pain, then that is immoral. It is treating entities as mere objects. This translation can often be carried over to humans, and often is. Torture of animals is often a precursor of sociopathic behaviour and is a hallmark of disturbed nutcases and serial killers.
If it is merely a by-product of a necessary process, i.e.: the gathering of food, or for the security of health and home, then we
do not intend the harm personally against the creature or individual in question. In this case, we are not attacking the entity per se, we are merely prioritizing the human entity over the animal entity. Thus, in cases where survival is not an issue, we can still view animals as sentient entitites deserving of respect and fair treatment. And this,in turn, extends to our attitude towards humans. If someone is trying to kill you, go ahead and have a go at him. Defend yourself. Otherwise, why pick a fight? This is how most of humanity lives... or wants to live. There is still that abberant part of society that wants to go out and kill anyone with the wrong shaped ears or funny noses.
One side note: On putting dogs and cats "to sleep". If you can
humanize a creature and kill it, then ergo, you should be able to kill a human if the need seems great. I've always thought Kevorkian had it right: if a guy wants to go out with dignity, it's his life... errh... death.
It can be argued that these view would lead one to believe that cannibalism is A-Ok (merely prioritizing the needs of one entity over another), but I'm still hung over the whole issue. Hey, if your mate is going to die anyway, at least he can go out knowing he gave you a good meal.
Also, who's to say that people are more important than animals? I think so, but then, that's just a personal, biased opinion.