see also "Pacifism and Vegetarianism"
I have been considering a more developed argument for pacifists to become vegetarians. Here is the simple argument:
A pacifist, in general, believes that humans should not be inflicted to the suffering of violence. And while I respect the view that holds a moral difference between humans and animals, I must ask: is this moral difference so great that human life should not be inflicted to the suffering of violence, but animal life may be inflicted by the suffering of violence, and for our mere pleasure?
I can expand on or argue this point, but it is that simple. Human life may be morally different than animal life, but does that mean it is wrong to ever inflict violence on humans but it is morally acceptable to inflict violence on animals for our pleasure?
Kathy Freston, in "Shameless Name Dropping," also espouses the view that vegetarianism is part of a general individual moral program of world peace--one which she shows is shared by some major intellectuals of world history. I recommend you read it.