The core of ethics runs deep in our species and is common to human beings everywhere. It survives the most appalling hardships and the most ruthless … - Peter Singer

Living a minimally acceptable ethical life involves using a substantial part of our spare resources to make the world a better place. Living a fully ethical life involves doing the most good we can.

Those who claim to care about the wellbeing 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 energy, and cease contributing to the clearing of forests; moreover, since a vegetarian diet is cheaper than one based on meat dishes, they would have more money available to devote to famine relief, population control, or whatever social or political cause they thought most urgent. … 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.

the fact that no one has come up with a really convincing reason for giving greater moral weight to members of our own species, simply because they are members of our species, strongly suggests that there is no such reason. Like racism and sexism, speciesism is wrong.