In many ways this is an appropriate question with which to conclude our discussion because the question itself reveals more about the history of the human/animal relationship than any theory, and it demonstrates our confusion about moral matters in general.

Many humans like to eat animal products. They enjoy eating them so much that they find it hard to be detached when they consider moral questions about animals. But moral analysis requires at the very least that we leave our obvious biases at the door. Animal agriculture is the most significant source of animal suffering in the world today, and there is absolutely no need for it. Indeed, animal agriculture has devastating environmental effects, and a growing number of health care professionals claim that meat and animal products are detrimental to human health. We could live without killing animals and could feed more of the world’s humans–the beings we always claim to care about when we seek to justify animal exploitation–if we abandoned animal agriculture altogether.

The desire to eat animal products has clouded some of the greatest minds in human history. Charles Darwin recognized that animals were not qualitatively different from humans and possessed many of the characteristics that were once thought to be uniquely human–but he continued to eat them. Jeremy Bentham argued that animals had morally significant interests because they could suffer, but he also continued to eat them.

Old habits die hard, but that does not mean they are morally justified. It is precisely in situations where both moral issues and strong personal preferences come into play that we should be most careful to think clearly. As the case of meat eating shows, however, sometimes our brute preferences determine our moral thinking, rather than the other way around. Many people have said to me, “Yes, I know it’s morally wrong to eat meat, but I just love hamburgers.”

Regrettably for those who like to eat animal products, this is no argument, and a taste for meat in no way justifies the violation of a moral principle. Our conduct merely demonstrates that despite what we say about the moral significance of animal interests, we are willing to ignore those interests whenever we benefit from doing so–even when the benefit is nothing more than our pleasure or convenience.

If we take morality seriously, then we must confront what it dictates: if it is wrong for Simon to torture dogs for pleasure, then it is morally wrong for us to eat animal products.

When we plant crops, we will inevitably displace and possibly kill sentient animals when we plant vegetables. Surely, however, there is a significant difference between raising and killing animals for food and unintentionally doing them harm in the course of planting vegetables, an activity that is itself intended to prevent the killing of sentient beings.

In order to understand this point, consider the following example. We build roads. We allow people to drive automobiles. We know as a statistical matter that when we build a road, some humans–we do not know who they are beforehand–will be harmed as the result of automobile accidents. Yet there is a fundamental moral difference between activity that has human harm as an inevitable but unintended consequence and the intentional killing of particular humans. Similarly, the fact that animals may be harmed as an unintended consequence of planting vegetables, even if we do not use toxic chemicals and even if we exercise great care to avoid harming animals, does not mean that it is morally acceptable to kill animals intentionally.

Moreover, because it takes so many pounds of plants to produce one pound of animal protein, we actually kill more animals in crop production when we are feeding those crops to animals rather than consuming the crops directly. So a vegan diet results in many fewer of those unintended and incidental deaths.

A related question is: why don’t plants have rights given that they are alive? This is the question that every vegetarian gets in the company of a nonvegan. These nonvegans may be otherwise rational and intelligent beings, but when confronted with a vegetarian, their discomfort with their diet often rises to the surface in the form of defensiveness.

No one really thinks that plants are the same as sentient nonhumans. If I ate your tomato and your dog, you would not regard those as similar acts. As far as we know, plants are not sentient. They are not conscious and able to experience pain. Plants do not have central nervous systems, endorphins, receptors for benzodiazepines, or any of the other indicia of sentience. Plants do not have interests; animals do.

It says nothing more than that some evil people may also be vegetarians. The question itself is based on an invalid syllogism: Hitler was a vegetarian; Hitler was evil; therefore vegetarians are evil. Stalin ate meat and was himself no angel. He was responsible for the deaths of millions of innocent people. What does that say about meat eaters? Just as we cannot conclude that all meat eaters have anything in common with Stalin beyond meat eating, we cannot conclude that all vegetarians have anything in common with Hitler beyond vegetarianism. Furthermore, it is not certain that Hitler actually was a vegetarian. And in any event, the Nazi interest in reducing meat consumption was not a matter of the moral status of animals but reflected a concern with organic health and healing and avoidance of artificial ingredients in food and pharmaceutical products that was linked to the broader Nazi goals of “racial hygiene.”

Another version of this question is that since the Nazis also favored animal rights, does this mean that animal rights as a moral theory is bankrupt and attempts to devalue humans? Once again, the question is absurd. In the first place, the question is based on a factual error. The Nazis were not in favor of animal rights. Animal welfare laws in Germany restricted vivisection to some degree, but they hardly reflected any societal preference for abolishing the property status of animals. After all, the Nazis casually murdered millions of humans and animals in the course of the Second World War, behavior not compatible with a rights position, human or otherwise. It is no more accurate to say that the Nazis supported animal rights than it is to say that Americans support animal rights because we have a federal Animal Welfare Act.

But what if, contrary to fact, the Nazis did advocate the abolition of all animal exploitation? What would that say about the idea of animal rights? The answer is absolutely clear: it would say nothing about whether the animal rights position is right or wrong. That question can be settled only by whether the moral arguments in favor of animal rights are valid or not. The Nazis also strongly favored marriage. Does that mean marriage is an inherently immoral institution? The Nazis also believed that sports were essential to the development of strong character. Does this mean that competitive sports are inherently immoral? Jesus Christ preached a gospel of sharing resources on an equitable basis. Gandhi promoted a similar message, as did Stalin. But Stalin also devalued human beings. Can we conclude that the idea of more equitable resource distribution has some inherent moral flaw that taints Jesus or Gandhi? No, of course not. We no more devalue human life if we accord moral significance to animal interests than we devalue the lives of “normal” humans when we accord value to certain humans, such as the severely retarded, and prohibit their use in experiments.