A person's attitude toward animals says much about the person. There are people who consider animals strictly as objects for the use of humans. There are people who deny that humans have any right to exploit animals at all, or to eat or use any animal product. As usual with any philosophical question, good sense is somewhere in between the irrational outliers.
The human species could not have emerged without killing animals. The organizational and technical skills needed to bring down game animals drove human evolution. Domestication of animals allowed civilization to develop. We are an omnivorous species and need certain nutrients only obtained from animals.
Our technological civilization still requires the intrusion upon the rights of animals in order to function. We have expropriated most of the land which wild animals had lived in, and fouled much of the rest. There are no good synthetic substitutes for materials such as leather.
In the near future, as we switch back to a more environmentally sustainable economy, the need for some forms of animal exploitation will increase. However, many forms of exploitation and abuse of animals ultimately harm humans and harm the natural environment as well.
But the existence of humans inevitably harms animals. To say we have no right to do so is to say we have no right to exist; that we are a rogue species. People are not all going to say "sorry critters, we were a mistake" and jump in the sea. So, the extreme vegan view, that we must avoid harming animals in any way, goes nowhere.
For better or worse, we humans are the lords of nature and the masters of animals. We are not managing nature very well right now but will improve over time, if we survive our follies at all. Many domesticated species of animal could no longer survive in the wild.
In many cases, domesticated animals live a longer and better life than their wild cousins do. In most cases now, what is left of wild animal populations survive only because we allow them to; we legislate their protection and survival.
As humans and our technology evolve, our reign over animals should become more beneficial and less harmful.
If total non exploitation of animals is against human nature, so is indifference to animal suffering. Tribes which live by hunting wild game generally have a cult of reverence for their prey species. Bushmen who kill an eland will perform a ritual apology to the eland spirit.
Many religions have doctrines about the treatment of animals. In Judaism and Islam, the meat of an animal which has been inhumanely raised and slaughtered is unfit to eat. In Hinduism, Buddhism, and Sikhism there is varying opinions about meat eating and a general principle of not harming animals.
Scientists find that the nervous systems of higher animals is not significantly different from our own. It is said that rather than suffering less than humans because they are less intelligent, they may suffer more because they cannot understand what is happening to them.
Normal people are distressed when someone behaves cruelly toward an animal. It gives them concern as to what that person would do to another human given the opportunity. It is very obvious to most people when animals are suffering and it distresses them in the same way as another human suffering would.
Certain moral philosophers propound that we should respect the rights of all animals for the same reasons we should respect the rights of all humans. Humans are superior to animals in understanding, but some humans are superior to other humans in understanding, and this does not give them the right to harm other humans with impunity. They do not mean that animals have the same rights as humans, but that their basic interest in being happy and not suffering is the same and should be given the same consideration.
The idea that animals have no rights or do not suffer seems to have developed in the modern age, with capitalism and rationalism. Like many ideas of capitalism and rationalism, disregard for proper treatment of animals is ultimately harmful to humans. Mishandling of animals in factory farms and slaughterhouses reduces the safety and quality of food, and breeds diseases. Something which must be tested to see if it kills an animal is likely not safe for humans and better not used. Even testing of medicines or medical procedures on animals is of dubious value.
Regard for the interests of animals is generally in the interests of humans, but the principle is not absolute. Where interests conflict, animals will lose.
There is no good and sensible idea which cannot be taken to a senseless extreme and so it is with animal rights. Animals are different from humans in different ways than humans are different from each other. Animals could not manage their own lives in the world humans made and the wild is no longer an option for most animals.
Despite technology, human life still depends on exploitation of animals. It is difficult and somewhat expensive to maintain a healthy diet free of all animal protein. It is easier to live on a diet which includes only eggs and dairy products, but not ideal.
Yet people often consume more meat than they need, which can also be unhealthy. Certain types of animal husbandry are more ecologically demanding than others. Raising and consuming food animals needs to be rationalized to environmental constraints.
Thus, there are environmental and health reasons for reduced animal protein consumption. But philosophical reasons are a personal preference. No one has any right to impose them on anyone else.
Certain Hindu groups will eat meat and wear leather, but maintain their "purity" by letting an "untouchable" caste do the dirty work of slaughtering and tanning.
Other groups will take their principle of doing no harm to animals to senseless lengths which cause themselves harm. For example, some will not kill vermin who severely degrade their food supply. The height of absurdity are certain religious groups who walk around with masks over their mouths to avoid breathing in insects.
The ethical issue in veganism is summed up very well in the Sikh holy book, the Granth Sahib; "Those who renounce meat, and hold their noses when sitting near it, devour men at night. They practice hypocrisy, and make a show before other people, but they do not understand anything about meditation or spiritual wisdom." (Page 1289 [6][7] Sri Guru Granth Sahib)
Some people simply need to feel superior to others. They adopt behaviors which give them a sense of purity and an illusion of being above their essentially animal selves. But there is always someone purer; nothing is ever transcendent enough.
This is not a respect for animals but a distain for human nature, even their own. Their behavior is as abnormal in its own way as is the total contempt for animal nature, though less harmful. They can live on their cloud, as long as they do not impose their ideas on the rest of us.
All we can say to them is that the human species is an omnivorous animal; get over it. However, we live with a different kind of "omnivore's dilemma"; we have feelings for what we must enslave or devour in order to live.
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