These are not very well supported by first-hand accounts, for example in my favourite history book of all times, The Conquest of Mexico, by Bernal Diaz del Castillo (one of Hernan Cortes' men), there are many descriptions of battles between the Conquistadores and the Aztecs and the Aztecs don't run away - the gunpowder and the horses make a great impression on them but they stay their ground and fight. Except, in Bernal Diaz's telling anyway, they are used to fighting ritualistic battles, where the point was to capture some of the enemy's men, to later offer up as sacrifices to their gods. So the Aztecs are playing for points, in a sense, whereas the Spaniards are fighting dirty and going for the throat. Obviously, the Spaniards have the tactical advatage and it's not because of their weapons and armour, or their steeds.
Another detail almost always overlooked is that the Spaniards were allied to local Mexicans that were enemy to the Aztecs of Tenochtitlan, particularly the people of Tlascalla. So in many of the battles with the Aztecs, the few hundred Conquistadores Cortes has with him are joined by thousands of Tlascallan warriors. This information is almost always left out of the narrative of the overwhelming technological superiority of the Conquistadores that allowed them to win despite being fewer in number. In truth, the forces of the Conquistadores joined by the Tlascallans and other enemies of the Aztecs were comparable in size with those of the Aztecs.
Finally, when the Aztecs decide enough is enough and start fighting for real, the Conquistadores run for their lives. This is the tale of La Noche Triste, The Sad Night, when the Conquistadores try to escape Tenochtitlan under cover of darkness with all the gold they've looted from Moctezuma's vaults, after he was killed (by his own subjects, according to Bernal Diaz, but, well... he would say so, wouldn't he?). They are chased through the streets of the city by the Aztecs who are in open revolt and catch and kill them one-by-one. Most drown in the waters around the city, many weighed down by the loot they cling to, stubbornly. Just a few barely escape with their skins and some of the gold. It's a sad night indeed- and it really puts the kibosh on the Conquistadores' crushing superiority, technological or other.
To summarise your comment (please correct me if I'm wrong): we should not eat animals because a) they're conscious, b) they do not want to be killed and eaten, and, c) we should apply to animals the same rules we apply to humans.
If I haven't misunderstood those- then I don't think that (a) is a particularly strong justification. On the one hand we know of societies where cannibalism was normal and even mandatory. For example, one of my favourite books of all times is "History of the conquest of Mexico" by Bernal Diaz del Castillo, a conquistador who campaigned with Hernan Cortés [1]. He reports the cannibalistic rituals of the Aztecs. It's a prime example of humans having no compunctions to eat other humans, consciousness and all (and offer their hearts to the gods, and sell their other parts to the town market, in the case of the Aztecs).
(c) is also not very good justifications because of cannibalistic socities: if a society accepts that humans can be killed and eaten, then it treats animals in the same way as humans if animals are killed and eaten in that society. Then, there is the example of Buddhist societies where the belief is that the souls of humans may reincarnete as animals. Literally, eating a cow might mean eating your grandfather or your grandmother (reincarnated) and you know that you, yourself, may come back as a farm animal and be slaughtered and eaten. Still, nonhuman animals are killed and eaten, and karma applies to everyone equally, human, animal, or plant.
As to (b) I think that even mordern societies accept that there are situations where the will of the individual is subsumed by laws and even the right to life is not absolute (the US, the leading Western democracy, exercises capital punishment). We incarcerate people who do not want to be incarcerated, we separate parents from their children who do not want to be separated, we even kill people who do not want to be killed.
Yes, we have rules against cruelty to animals. But those laws, I think, never cover putting an animal to death in an acceptable manner that minimises its suffering when the purpose is to eat it. Pretty much every human society throughout history has accepted that at least some nonhuman animals may be killed for food. Restrictions are placed often on what animals can and cannot be killed or eaten (Hindus won't kill cows, Muslim and Jewish people will not eat pork and will only eat animals killed in a special manner, etc). However, there is always some class of animals that the majority of people will eat unquestioningly.
In the article above, I note, for example, that the subject is killing and eating cows. Not, say, chicken, fish, insects, sheep, pork, horses, dogs, cats, snails, deer, ducks, etc etc. In fact, some of those animals (insects, in particular) have been offered up as an alternative to killing and eating cows, although not by the author of this article as far as I can tell.
It seems to me then that the justification you offer is not perhaps the one envisioned by the author of the article, or perhaps, a certain viewpoint that the article represents. For this veiwpoint there seems to be a particular issue about eating spedifically beef. I am not sure I understand this but, beyond the obvious commercial interest in marketing a product as anti-beef eating, there also seems to be a heavy focus on a particular demographic, which I think is in particular a US demographic.
Finally, personally I don't accept your three justifications. I understand full well that the animals that have died so that I may eat their flesh are conscious and do not want to die. I do not feel there is anything unethical in killing an animal to eat it, because this is how eating works: you have to kill something to eat it and that something rarely agrees to be eaten. I myself will one day die regardless of whether I agree to it or not. I may be killed, and I may be killed and eaten (e.g. by a shark when I swilm in the sea; or even killed without being eaten in that case). I don't think killing and eating other animals is human exceptionalism. I think hyman exceptionalism is responsible for the idea that eating other animals is wrong: no other animals seem to have such rules; why should we, of all animals, have them, if not to pretend we're not like other animals?
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[1] https://en.wikipedia.org/wiki/Bernal_D%C3%ADaz_del_Castillo#...
Edit: I should say I do feel compassion for the animals that have died so that I may eat their flesh. For that reason, I make sure ot never throw meat away. The poor animal died so that I could eat it so I may as well eat it.
http://www.gutenberg.org/files/32474/32474-h/32474-h.htm
http://www.gutenberg.org/files/32475/32475-h/32475-h.htm
That's the bees knees and the cat's pajamas when it comes to the downfall of the Aztec Empire at the hands of Cortes' small band of conquistadores (plus a few thousand Tlascalans and other enemies of the Empire), a first-hand account from one of the conquistadores.
It's all in there: the pious, self-mutilating Aztec priests who practiced human sacrifice, the strange way the Mexicans did warfare and their reaction to muskets and horses, La Noche Triste and Alvarado's Leap, Moctezuma's death at the hands of his captors, Dona Marina, and of course, the deadliest part of it all, the decimation of the Mexican population by smallpox carried by the Europeans.
It's been called the most beautiful story ever told (no link, sorry) and it is. Beautiful, but also tragic, brutal, horrifying, bloody and full of senseless killing and pointless death and destruction.
You might want to read it if you enjoyed New Revelations...
This article might help me reinspire myself with this history.
I sometimes like to wonder what if, and wonder how vastly different world history could have been. If the Catholic conquistadors had managed to overcome superstition and fear of the devil to try Teonanácatl, Peyotl, Cohoba and Ayahuasca.
The review says that "most estimates of the frequency of human sacrifices in Tenochtitlan come from an unfounded assertion by the Franciscan friar Diego Valadés, who was born twenty-two years after the city fell. Valadés claimed that between 15,000 and 20,000 people were sacrificed in Tenochtitlan per year." Later, "Cortés’s confessor and the first formal historian of the Conquest of Mexico, raised the figure to 50,000."
"The number is remarkable for how preposterous it is: more than 137 sacrifices a day, five an hour, one every twelve minutes, twenty-four hours a day. Aztec sacrifice was a nonmechanized process that demanded extensive ritual preparation and an individually selected victim, and archaeologists have never found evidence to support the Spaniards’ figures. As [the book's author] points out, although human skulls have been retrieved from ritual burial grounds close to Tenochtitlan’s Templo Mayor (the city’s main temple), most of the sacrificial remains that have been found belong to animals—wolves mostly—and these remains don’t add up even to hundreds of victims, let alone thousands."
Also, regarding cannibalism, "owing to a [Spanish] royal law from 1503, an enemy fighter who practiced cannibalism could be enslaved for life, and shortly before Cortés left Cuba for Mexico a smallpox epidemic caused a drastic reduction in native manual labor in the Caribbean. The later narratives that were so insistent on the subject of cannibalism are always, in [the author's] view, related to the conquistador generation’s claim to cost-free indigenous servitude. This argument became especially important after the Crown abolished native slavery and gave indigenous subjects rights identical to those of Spaniards in the New Laws of 1542."