“What one generation finds ridiculous, the next accepts; and the third shudders when it looks back on what the first did.”

“Philosophy ought to question the basic assumptions of the age. Thinking through, critically and carefully, what most of us take for granted is, I believe, the chief task of philosophy, and the task that makes philosophy a worthwhile activity.”

“Arguments for preservation based on the beauty of wilderness are sometimes treated as if they were of little weight because they are "merely aesthetic". That is a mistake. We go to great lengths to preserve the artistic treasures of earlier human civilisations. It is difficult to imagine any economic gain that we would be prepared to accept as adequate compensation for, for instance, the destruction of the paintings in the Louvre. How should we compare the aesthetic value of wilderness with that of the paintings in the Louvre? Here, perhaps, judgment does become inescapably subjective; so I shall report my own experiences. I have looked at the paintings in the Louvre, and in many of the other great galleries of Europe and the United States. I think I have a reasonable sense of appreciation of the fine arts; yet I have not had, in any museum, experiences that have filled my aesthetic senses in the way that they are filled when I walk in a natural setting and pause to survey the view from a rocky peak overlooking a forested valley, or by a stream tumbling over moss-covered boulders set amongst tall tree-ferns, growing in the shade of the forest canopy, I do not think I am alone in this; for many people, wilderness is the source of the greatest feelings of aesthetic appreciation, rising to an almost mystical intensity.”

“In an earlier stage of our development most human groups held to a tribal ethic. Members of the tribe were protected, but people of other tribes could be robbed or killed as one pleased. Gradually the circle of protection expanded, but as recently as 150 years ago we did not include blacks. So African human beings could be captured, shipped to America, and sold. In Australia white settlers regarded Aborigines as a pest and hunted them down, much as kangaroos are hunted down today. Just as we have progressed beyond the blatantly racist ethic of the era of slavery and colonialism, so we must now progress beyond the speciesist ethic of the era of factory farming, of the use of animals as mere research tools, of whaling, seal hunting, kangaroo slaughter, and the destruction of wilderness. We must take the final step in expanding the circle of ethics. -”

“If possessing a higher degree of intelligence does not entitle one human to use another for his or her own ends, how can it entitle humans to exploit non-humans?”

“In the past 20 years alone, it adds up to more death than were caused by all the civil and international wars adn government repression of the entire twentieth century, the century of Hitler and Stalin. How much would we give to prevent those horrors? Yet how little are we doing to prevent today's even larger toll and all the misery that it involves? I believe that if you read this book to the end, and look honestly and carefully at our situation, assessing both the facts and the ethical arguments, you will agree that we must act.”

“If morality is always relative to one’s own society, then you, coming from your society, have your moral standards and I, coming from my society, have mine. It follows that when I criticize your moral standards, I am simply expressing the morality of my society, but it also follows that when you condemn me for criticizing the moral standards of your society, you are simply expressing the morality of your society. There is, on this view, no way of moving outside the morality of one’s own society and expressing a transcultural or objective moral judgment about anything, including respect for the cultures of different peoples. Hence if we happen to live in a culture that honors those who subdue other societies and suppress their cultures, then that is our morality, and the relativist can offer no cogent reason why we should not simply get on with it.”