Overview of the argument against meat eating
Peter Singer—Princeton University and University of Melbourne professor and pioneer of the animal liberation movement—has long argued that, if it is possible to survive and be healthy without eating meat, fish, dairy, or eggs, one ought to choose that option instead of causing unnecessary harm to animals. In Animal Liberation, Singer argued that, because non-human animals feel, they should be treated according to utilitarian ethics. Singer's work has since been widely built upon by philosophers, both those who agree and those who do not, and it has been applied by animal rights advocates as well as by ethical vegetarians and vegans.
Ethical vegetarians say that the reasons for not hurting or killing animals are similar to the reasons for not hurting or killing humans. They argue that killing an animal, like killing a human, can only be justified in extreme circumstances; consuming a living creature just for its taste, for convenience, or out of habit is not justifiable. Some ethicists have added that humans, unlike other animals, are morally conscious of their behavior and have a choice; this is why there are laws governing human behavior, and why it is subject to moral standards.
Ethical vegetarian concerns have become more widespread in developed countries, particularly because of the spread of factory farming, more open and graphic documentation of what human meat-eating entails for the animal, and environmental consciousness. Some proponents of meat-eating argue that the current mass demand for meat has to be satisfied with a mass-production system, regardless of the welfare of animals. Less radical proponents argue that practices like well-managed free-range rearing and the consumption of hunted animals, particularly from species whose natural predators have been significantly eliminated, could satisfy the demand for mass-produced meat. Reducing the worldwide massive food waste would also contribute to reduce meat waste and therefore save animals. Indeed, according to the Food and Agriculture Organization of the United Nations, about a third of the food for human consumption is wasted globally (around 1.3 billion tons per year).
Some have described unequal treatment of humans and animals as a form of speciesism such as anthropocentrism or human-centeredness. Val Plumwood (1993, 1996) has argued that anthropocentrism plays a role in green theory that is analogous to androcentrism in feminist theory and ethnocentrism in anti-racist theory. Plumwood calls human-centredness "anthropocentrism" to emphasize this parallel. By analogy with racism and sexism, Melanie Joy has dubbed meat-eating "carnism". The animal rights movement seeks an end to the rigid moral and legal distinction drawn between human and non-human animals, an end to the status of animals as property, and an end to their use in the research, food, clothing, and entertainment industries. Peter Singer, in his ethical philosophy of what it is to be a "person", argues that livestock animals feel enough to deserve better treatment than they receive. Many thinkers have questioned the morality not only of the double standard underlying speciesism but also the double standard underlying the fact that people support treatment of cows, pigs, and chickens that they would never allow with pet dogs, cats, or birds.
Jay Bost, agroecologist and winner of The New York Times' essay contest on the ethics of eating meat, summarized his argument in the following way: "eating meat raised in specific circumstances is ethical; eating meat raised in other circumstances is unethical" in regard to environmental usage. He proposes that if "ethical is defined as living in the most ecologically benign way, then in fairly specific circumstances, of which each eater must educate himself, eating meat is ethical." The specific circumstances he mentions include using animals to cycle nutrients and convert sun to food. Ethicists like Tom Regan and Peter Singer define "ethical" in terms of suffering rather than ecology. Mark Rowlands argues that the real determinant of whether it is ethical to cause suffering is whether there is any vital need to cause it; if not, then causing it is unethical.