"We pride ourself on our uniquely human ability to make ethical judgements and take moral responsibility for our actions. To protect the weak and gentle from the homicide aggressions of the strong and ruthless, we establish laws decreeing that one who wantonly murders another be severely punished for his evil deed, and this often involves the sacrifice of his own life. In human relationships we disavow, or like to believe we disavow, the morality of might makes right. But where non-humans are concerned, especially those whose flesh or skins we covet, or on whose bodies we wish to conduct lethal experiments, we oppress, and exploit them freely, justifying our harsh treatment on the ground that since they are beings of inferior intelligence, with no sense of right and wrong, they have no rights. If the value of a life, human or non-human, is to be judged by that beings intelligence, then, like the Nazis, we ought to put to death senile and mentally retarded human beings, for many animals are better able to interact with their own species than, say, a mentally retarded adult."
Animal Rights FAQ
The Post-Darwinian Transition