We’ve heard arguments about the environmental disadvantages of eating red meat. We’ve also heard about the possible health impacts. Christine Korsgaard, the Arthur Kingsley Porter Professor of Philosophy at Harvard University, stresses another important consideration that receives much less public attention: the ethics of eating animals.

Korsgaard upholds that meat production is environmentally harmful, inefficient for a growing population and worse for our health than a vegetable diet. But she further argues that humans do not have a right to kill animals. This, she acknowledges, is a point that “many decent people would reject.”

The fallacy that human beings make, Korsgaard argues, is thinking that our differences from animals justify our killing them. While it is true that “the loss of life matters to a human being in certain ways that it wouldn’t matter to another sort of animal,” she says, “I don’t think it follows that a non-human animal’s life is of no value to her: after all, the loss of her life is the loss of everything that is good for her.”

While it may be worse to kill a human than a non-human, that “does not imply that non-human animals may be sacrificed to human interest generally.” Korsgaard notes that there are many important differences between the species, but that they are just that—differences. Most humans tend to interpret these differences as superiority on the part of humans. We are rational and we have standards of morality, we judge others and ourselves. As she points out these specie features, it’s hard not to recognize an irony in the fact that humans justify killing other species because of our highly developed morals. “You are not superior to someone when altogether different standards apply,” Korsgaard argues.

It’s even possible that eating other animals negatively impacts human beings. Korsgaard concludes that we have “a certain sense of solidarity” with other sentient beings, and harming fellow creatures cannot be a good way to live.

Her most vehement argument is against factory farming. The more people eat meat, the more the practice will be necessitated: “the whole human enterprise will be supported by a bloodbath of cruelty, hidden away behind the closed walls of those farms.” Anyone who has seen the documentary Food, Inc. recognizes the kind of dark secrecy she alludes to. Even those who can justify killing animals cannot justify factory farming, Korsgaard says.

Can we still imagine ourselves as a natural link in a chain of life when there is nothing natural about the way we raise and eat our food?

The argument against factory farming is a very strong one: few people can defend unnecessary suffering. When considering the ethical aspects of eating meat, I personally often found myself nostalgically imagining the human as part of a natural circle of life—where animals kill and eat each other to survive.

Korsgaard provokes some important questions: what if it is not natural for animals to eat meat? How do we know? What if the only way that the growing human population can eat meat is through factory farming practices? Can we still imagine ourselves as a natural link in a chain of life when there is nothing natural about the way we raise and eat our food? If people believe that the way their food is raised is unethical, do they have a moral obligation not to eat it?