I just, after a ridiculously long haitus, finished reading Peter Singer's excellent Animal Liberation.
Toward the end of the book, I found this one excerpt that for me sums up some key arguments for becoming vegetarian, especially for social justice activists who argue that animal rights are just not a focus for them, amidst the certainly overwhelming list of important causes activists need give attention to. Here's the excerpt:
"the idea that 'humans come first' is more often used as an excuse for not doing anything about either human or nonhuman animals than as a genuine choice between incompatiable alternatives . . . Granted, everyone has a limited amount of time and energy, and time taken in active work for one cause reduces the time available for another cause; but there is nothing to stop those who dvote their time and energy to human problems from joining the boycott of the products of agribusiness cruelty. It takes no more time to be a vegetarian than to eat animal flesh. In fact . . . those who claim to car about the well-being of human beings and the preservation of our environment should become vegetarians for that reason alone. They would thereby increase the amount of grain available to feed people elsewhere, reduce pollution, save water and eregy, and cease contributing to the clearing of forests; moreover, since a vegetarian diet is cheapder than one based on meat dishes, they would have more money availalbe to devote to famine relief, population control, or whatever social or political cuase they thought most urgent. I would not question the sincerity of vegetarians who take little interest in Animal Liberation because they give priority to other causes; but when nonvegetarians say that 'human problems come first' I cannot help wondering what exactly it is that they are doing for human beings that compels them to continue to support the wasteful, ruthless exploitation of farm animals." (pg. 220-221)