I realize that sourcing wikipedia is kind of lazy but I lack the time to read entire books full of every sort of misinformation that happens to be going around.
https://en.wikipedia.org/wiki/The_Vegetarian_Myth
From the article:
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For the earth to survive, Keith thinks, the human population needs to be reduced by more than 90 percent. She also argues that the human food-supply needs to come mainly from hunting and small-scale animal husbandry.[4]
Criticism:
Sami Grover, referencing "Jason V", says Keith's book is filled with "factual errors and fallacious thinking". Furthermore, Jason V writes that Keith fallaciously uses her ex-vegan status in an attempt to depict herself as an authority on the subject.[11]
Patrick Nicholson writes that the book misinterprets scientific articles, cherry-picks facts, uses strawman arguments and relies heavily on anecdotes and faulty generalisations.[5] Ian Sinclair writes that Keith's arguments are "full of lazy thinking, willfully ignorant logic and glaring omissions".[12]
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My thoughts:
I think its meaningful or even sane to suggest that virtually everyone stops having babies or dies and all the survivors go play hunter gatherers in the woods.
I think our present trajectory is obviously unsustainable but that doesn't make any alternative suggestion reasonable.
Our future is the stars or extinction. In between we have to find a sustainable reasonable way to live civilized lives. This probably isn't horrifically complicated we don't have to reduce our population by 90% we just have to not keep increasing it and make do with simpler and less.