1. Prison. The philosophy of prison as punishment is wrong, but the idea of keeping a murderer isolated from potential victims isn't. So don't throw out the baby with the bath water.

2. Animals, just like humans, die. There's no way around it. Even if the entire world decides not to eat a particular goat, that goat will die. And when an animal dies, it gets eaten - no exception. Either by microorganisms, or higher level organisms. The problem isn't why animals die, it's how animals live. Even if an animal is bred for food, it doesn't have to lead a miserable life, and it doesn't mean we should not respect that life on its own merit. So again, don't throw out the baby with the bath water.

3. I agree. But say, if an old animal wants to die, can I eat it?