Examine your behavior. If you are evil, know as soon as possible and can fix it.
The response: "Majority of people is doing it." is not good enough. Some people insist that eating meat is wrong. I should think about it myself. Maybe they are right.
I thought about it. It's alright to eat animals. There are my reasons why.
In this post, I talk about animal suffering. There are environmental and health reasons. Post about the environment will come in the future.
Animals have a lot of responses similar to humans. They can feel emotions, but not as richly as humans (check this book).
Animals are less in a few aspects. Humans can override their basic instincts. We do things that oppose our nature. For we can starve ourselves, animals cannot do it.
We train animals to do what we want, but they wouldn't do that themselves. They don't transmit their knowledge. They communicate on a limited scale.
Every human has enormous potential. He can use his abilities to reduce suffering. Humanity created a civilization that allows us to change the world. Someone would say for the worse (Neandertals and animals useless for us), but the ability counts. Animals have a limited potential to do anything.
There are also other things like burying the dead or creating art.
If there is some ideal product of the evolution of everything alive, humans will be at least an instrument in its creation or might morph to it.
For me, it means that humans are qualitatively different from animals, not just quantitatively. It means for a question: "How many cats would you sacrifice to save one person?" I would answer: "Any number that does not negatively impact the ecosystem."
The alternative for farm animals is non-existence. We farm animals effectively: cows provide meat and milk, and their population is enormous because of it. Moreover, we cultivated farm animals. Some would have a hard time surviving in the wilderness.
I prefer living, and there is a large margin. Life would need to get much worse before I would rather not exist.
If I could choose between dying now or living as a cow on a farm (meaning having food, water, small space, and a bit packed with other members of my species) I would choose the farm cow life.
I would still choose it even though we are a bit unfair. I should get more mental stimulation than stables. Cows in the wild don't do too much. They stand on a field and chew and run around a bit.
We don't know how cows think. I expect that the mental life of a cow is pretty simple. They don't even seem to communicate on the field. A similar constraint for me might be: eat junk food, don't go outside, don't watch youtube, don't play board games, study machine learning.
But what do we know? Maybe cows are nihilistic philosophers. They might prefer non-existence against any form of pleasurable existence. Anyway, we give them what we desire.
Life in nature is brutal. It's nobody's fault. Suffering is part of life.
We imagine nature as a peaceful place. Maybe it's a more natural place, but not peaceful. Every predator eats. It doesn't care how stressed the cow is during its life (stress hormone reduces growth and efficiency). It just tries to kill with teeth and claws. Industrial killing is faster and "cleaner".
If you say that this is not natural, you should die with a high probability during your first few months, have a first child between fifteen to seventeen (if you are a woman or lucky man), and then die of some preventable disease or injury at thirty. If you don't wish the natural life for yourself, why would you say it's better for animals?
For life, you do need resources. Some of them directly harm animals. You don't want pests (rats) in your house or city. They are killed, similarly to animals that damage fields of crops.
Any material you use is taken from nature. The forest had to make way for farms, mines, or roads.
You need other people to produce resources for you. Animals suffer on a farm. Humans have to work, and you consume the work. If you don't, they might do something else instead.
And then, your inadequacies and shortcomings make life more miserable for others.
In my opinion, the harm you cause by eating animals is nontrivial but worth it. If your framework is to eliminate suffering, vegetarianism does not absolve you to not think about other sources of suffering.
I like the mindful approach of my friend. He eats meat, but not too much and responsibly. Anytime he is prepared to eat it, he reminds himself of the suffering necessary to produce the food. You might call it prayer.
Prayer is a good ritual anyway. It reminds you of the sacrifice to get the meal for you. It makes you aware that you should not waste it and make it worth it.
To make it worth it, do things that overweight the suffering caused by your existence. Making the sacrifice worth it is not hard. Start with kind words for people around you. Continue by doing something difficult and worthwhile.
The above applies if you like the taste of meat or think that meat is better nutrition than the alternatives.
Healthwise, I think it's better to eat meat. Humans evolved to eat meat. Forfeiting it might cause health troubles and might make your life harder. (And I'm considering that we will live longer than our ancestors, so small optimization in nutrition might take you a long way.)
I think it's worth it and ok to eat meat.
Animals can suffer, but their capacity to suffer is smaller than that of humans. Moreover, the ability to reduce suffering is almost nonexistent in animals. But humans are very effective in reducing suffering.
In my opinion, life is better than nothing. And that's true for a life of almost any quality. Moreover, life on a farm is not incomparably crueler compared to nature.
Your existence causes harm, no matter what you do or eat. The correct framework is not to aggressively reduce suffering. Try to have a positive impact, so you overweight the damage you cause. That way, you are choosing life.
And one more thing, if you are an ethical vegetarian with a cat or dog, you are raping logic with a wooden stick that leaves splinters.