If you want to start a fight, just raise this question in a mixed group of meat eaters, vegetarians and vegans!
One of the core problems modern Western people have is that we've forgotten that the rest of nature is alive. This is why we feel free to mistreat the land, the plants and the other animals -- to the point where we're actually destroying our own life support systems and those of thousands of other creatures.
Many indigenous peoples have been trying to tell us for a long time that this arrogant attitude just doesn't work in the long run. The Lakota Sioux talk about the animals, plants and the rest of nature as "all our relatives" -- and perhaps this can give us a different perspective on the whole question of if and/or how we devour these relatives.
For of course there is no life for us if we don't do what every other creature in nature does: eat our relatives -- even if it's only our plant relatives. But it's HOW we go about doing this that's important. Do we treat them as inanimate, dead objects just here for human use or as fellow sacred beings with whom we share this fragile water planet?
It may shock hardcore vegans and vegetarians to know that growing their food involves killing or displacing other animals. Any home gardener or farmer who grows veggies and fruit must compete for that harvest with some of our "relatives" who would like to eat it before we do: the gophers, insects, rats, deer, raccoons, rabbits, moles, voles and more. In fact, merely clearing land to grow our favorite veggies and fruit destroys the habitat of many other animals and native plants -- both above and below ground. This is why there is now a growing movement in agriculture to leave a certain percentage of every farm for wildlife. Finding humane ways of removing or killing these competitors is a huge ethical and practical challenge for the farmer or edible gardener.
Organic gardeners and farmers have also learned that other animals -- the "beneficial" insects, worms, fungi and other soil creatures -- are absolutely critical for human survival and that of our favorite foods. These allies become the grower's treasured friends, and harming them with chemicals and unfriendly soil practices becomes out of the question.
The "should I eat meat or other animal products?" debate is incredibly complicated. Quite apart from the health consequences (and research is trying to get us answers to this issue but most studies don't yet distinguish between eating healthy organic, humanely raised meat, eggs and milk vs. eating factory-farmed animal products), what are the ethical considerations? Is it possible to find a way to allow animals the freedom to live as they were evolved to live and at the same time use their products or flesh to nourish ourselves? Is there such a thing as a humane kill?
And do animals have "rights"? And if so, rights to what? This is becoming a hotly-button political issue.
And what about waste? Is it ethical to kill an animal, eat part of it and throw most of it away? Studies are revealing that a shocking percentage of food in wealthy nations is thrown away -- perhaps the ultimate disrespect of the animal's sacrifice. What makes it worse is the millions of people on the planet who are starving.
Perhaps the answer to all these thorny questions lies in a renewed understanding of humans as one animal species among many. If we see ourselves once more as an integral part of nature instead of a completely different and superior entity, hopefully we can find a way to be part of the whole but in a truly "humane" way that is worthy of the great gift of consciousness we have been blessed with.
So if we do choose to eat animal products, we need to do so with the attitude some indigenous cultures recommend: recognition that cow, pig, chicken, deer, corn and worm are all sacred creatures worthy of respect as we interact with them -- and even as we kill them. In some cultures it is a traditional practice to ask permission from an animal or plant before we hunt, pick or eat it; and to express thanks for its sacrifice. Perhaps this is the least we can do before we take life or milk or eggs -- for the survival of our children and the human community.