Speciesism—the word is not an attractive one, but I can think of no better term—is a prejudice or attitude of… — Peter Singer

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 animals themselves are incapable of demanding their own liberation, or of protesting against their condition with votes, demonstrations, or boycotts. Human beings have the power to continue to oppress other species forever, or until we make this planet unsuitable for living beings. Will our tyranny continue, proving that morality counts for nothing when it clashes with selfinterest, as the most cynical of poets and philosophers have always said? Or will we rise to the challenge and prove our capacity for genuine altruism by ending our ruthless exploitation of the species in our power, not because we are forced to do so by rebels or terrorists, but because we recognize that our position is morally indefensible? The way in which we answer this question depends on the way in which each one of us, individually, answers it.

How far down the evolutionary scale shall we go? Shall we eat fish? What about shrimps? Oysters? To answer these questions we must bear in mind the central principle on which our concern for other beings is based. As I said … the only legitimate boundary to our concern for the interests of other beings is the point at which it is no longer accurate to say that the other being has interests. To have interests, in a strict, nonmetaphorical sense, a being must be capable of suffering or experiencing pleasure. If a being suffers, there can be no moral justification for disregarding that suffering, or for refusing to count it equally with the like suffering of any other being. But the converse of this is also true. If a being is not capable of suffering, or of enjoyment, there is nothing to take into account.