@lid

Ok. So if your criterion of not eating an animal is how long they've been domesticated, when can we stop eating cows and pigs (and chickens and turkeys and crows and mud and our hearts...)? I'm not a paleozoologist so my numbers are hazy on this one, but I think for dogs, it was about 14000 bce, and 6000 years later for cows and pigs (feel free to correct me on this one). The conclusion is, I guess,we can wait another 6000 years and then pigs and cows will be off the menu. Sorry, chickens, your turn will come later.

And as for your point about the pyramids, I vaguely recall seeing a Discovery documentary about that. Well, I'd say your syllogism is watertight.

1. The pyramids were built without beasts of burden.
2. All ancient buildings were built like the pyramids.
3. Ergo, no ancient buildings were built like the pyramids.
   

Good work! Aristotle would be proud of you (but not Frege).