If veganism were a tower, the health argument wouldn’t be the walls or the ceiling, the foundation or the sign above the door. Rather, it would be a load-bearing beam; far from flashy, not always discussed, but necessary to keep everything in shape. Without it, the building either sinks on its foundations or comes crashing down.

For veganism, the sign above the door is an ethical claim: “It’s wrong to eat animals.” Simple and compelling, enough so that veganism is one of the world’s fastest-growing diets. You’d be hard-pressed to find a Westerner who hasn’t heard the central ethical claim of veganism.

Nonetheless, veganism is in fact two ethical arguments. Though rarely articulated, they exert tremendous pressure on public opinion. They are:

Argument 1:

1. Nonhuman animal life is as valuable as human life.

2. An animal-based diet requires the death and suffering of many animals to feed one human.

3. Humans can survive without eating animals.

Therefore,

4. It’s wrong to eat nonhuman animals.

Argument 2:

1. Nonhuman animal life has significant value.

2. An animal-based diet requires the death and suffering of many animals to feed one human.

3. Humans can survive and thrive without eating animals.

Therefore,

4. It’s wrong to eat nonhuman animals.

I’ve formulated these arguments, as vegans often do, without using the word “health.” But if you look closely, you’ll see that health is the main difference between the two; it’s hidden in that little word “thrive.” We’ll define “thrive” the way vegans typically do: “thriving” means to be in such good health that changing diets won’t significantly improve things. For a vegan to “thrive” they must be in a state of health equal or better than what they’d be in eating meat.

Argument 1 is valid* whether or not vegans thrive. If a nonhuman animal’s life is as valuable as a human’s, there’s no justification for killing and eating them, regardless of what happens to our health. No utilitarian calculus can justify killing many beings to improve the health of one being of equal value (the average meat-eater consumes about one animal per year, and if you’re a Westerner who eats meat, you’re above average; virtually every Western meat-eater consumes more than one animal in his or her lifetime).

Argument 1 has the advantage of not relying on any kind of argument that veganism is healthier. But it has the disadvantage of being far less compelling: “Become vegan: you’ll suffer brain fog, anemia, digestive issues and low-level depression, but it’s better than chickens and cows dying, because your life is no more valuable than theirs.”

It’s also less compelling to those who are already vegan, as people are drawn towards ideologies that offer totalizing solutions. They want to believe that their ideology will solve all or at least many problems, without any drawbacks. Veganism is much more rewarding if it’s a way to stand up for animals, save the planet and improve your health, all at once. If veganism is presented as a utilitarian tradeoff that involves damaging self-sacrifice, it loses a lot of punch.

If push came to shove, and veganism were proven unhealthy many vegans would fall back on argument 1 and stick to their veganism (though the recent rash of ex-vegans shows that many, also, would not). That being said, argument 2 is by far the more popular vegan argument. And it’s easy to see why: if argument 1 makes things tough for vegans, argument 2 should really make meat-eaters squirm. If argument 2 is sound** it removes all justification for eating meat beyond pure hedonism. If you can be as healthy as you are now without the killing and suffering of animals, then why are you participating in that terrible institution?

For meat-eaters, the question of the health truly is the core of the debate: in the conceptual tower of the conscious meat-eater, health issues are, indeed, the walls, the ceiling, the foundation and the sign above the door. As most of us are meat-eaters, this aspect of the debate will likely end up determining the historical fate of meat-eating: whether it remains a staple of the human diet, or whether it comes to be looked back upon as a moral crime akin to slavery.

For more information on veganism and health, check our podcast episode on the topic, or check out these resources:

https://en.wikipedia.org/wiki/Veganism#Health_research

https://www.carnismdebunked.com/health-nutrition

https://selfhacked.com/blog/16-nutrients-vegans-arent-getting/

https://chriskresser.com/why-you-should-think-twice-about-vegetarian-and-vegan-diets/

*Valid argument: An argument where the premises lead logically to the conclusion.

**Sound argument: An argument where the premises lead logically to the conclusion and the premises are correct. In a sound argument, the conclusion must be accepted. Note that a valid argument can be unsound if one of the premises is incorrect.