your arugment:
1.we avoid pain because pain is a precersor to injury/death
2.animals avoid pain for the same reason
3.therefore, we should not cause pain to animals
4.therefore, we should not eat animals.
1-3 is perfectly valid, 4 is not. It does not follow that in killing an animal it has to feel pain. While you may be correct in saying that right now, in current practices, it is the case it need not be. Its easy to imaginge another world where animals are killed painlessly and immediately.
Hey Scott, for the record, I think you're spot-on about point 4.
But whether or not it's easy to imagine a world where animals are killed painlessly, I don't know. But I know the story doesn't end there. What about their families? Their grieving companions? If I shot your partner painlessly and immediately, she might not suffer, but surely you will. There is still needless suffering in this equation.
If we COULD eat animals without CAUSING pain and/or suffering, the argument becomes very different. Indeed, eating road kill doesn't cause pain or suffering (not that it sounds very appetizing!), similarly, eating meat found in a dumpster is not contributing to the cycle of suffering either (they call it freeganism).
However, most people in our society don't eat roadkill, and aren't freegans. Most people buy their processed animal flesh shrink-wrapped from the supermarket. Before it was at the supermarket it was at the abattoir being dismembered, before that, she was a terrified and confused animal who perhaps wasn't stunned properly before she had her throat slit and was left to bleed to death. Before she entered the abattoir she was crammed tightly onto a truck and left without food or water for extended periods. Before that she was locked in a tiny metal cell so small that she couldn't turn around. She was denied social interaction, mental stimulation, and the freedom to express basic natural instincts which give quality of life. She was forcibly impregnated time and time again until her frail body could no longer take the physical stress of repeated gestation. Perhaps she became lame from denial of exercise, or perhaps her reproductive system simply shut down. Before that she had her tail cut off without anaesthetic, parts of her ears cut off with scissors (again, without anaesthetic), and also had her teeth painfully broken as a baby before she was prematurely and stressfully torn away from her mother. She was brought into this world solely to be killed. Her welfare and quality of life came second to the profit she could yield, and for this reason the laws were long ago bent so that animals raised for food like her could be subjected to extreme acts of cruelty -- without the threat of legal prosecution.
THIS is the reality for tens of billions of animals raised every year to feed people. Nobody can deny the suffering this causes. This is what we object to. This is why we are vegetarian, and vegan.
(But if you want to eat road kill, go right ahead

)