What Does the Claim that Veganism is Unhealthy Entail About the Ethics of Veganism?


What if a vegan diet were unhealthy?

(What’s Wrong? is grateful to Jake Monaghan (Department of Philosophy, University at Buffalo) for this original submission)

I should say at the outset that I did not write this essay to convince you to be a vegan. Rather, I think a common objection to veganism raises an interesting philosophical question about killing in self-preservation or for the purpose of improving one’s life. Much has been written on killing in self-defense, but much less (to my knowledge) about the more general issue of killing a non-aggressor in order to preserve or improve one’s life.

A vegan diet is, for almost everyone, perfectly healthy. This doesn’t stop people from objecting to the claim that veganism is a moral requirement on the grounds that a healthy diet requires animal products. When I cover moral status and animal ethics in my bioethics and introduction to ethics courses, at least one student makes this objection each semester after being presented with arguments for the claim that most animals have moral status. Those of us who are not professional ethicists often have difficulty finding fault in such moral status arguments, and thus fall back on the health-based objection.[1] Clearly, then, the myth that veganism is unhealthy is as persistent and detrimental to the animal welfare movement as is the myth of “happy meat.”

Often, animal welfare advocates focus their energy on disabusing carnists of this notion.[2] They will point to the China Study[3], to their own years or decades long experience as a vegan, to the USDA’s and others’ remarks on vegan and vegetarian diets correlating with healthier individuals, to successful vegan professional athletes[4], and so on. This is all worthwhile and (somewhat) effective.

What I want to do, however, is consider what happens to the case for veganism if the health-based-objectors are correct. Suppose that being a vegan shaves a few years off of one’s life, keeps one from running as fast or as far, or lifting as much weight, as one otherwise might have had they consumed a diet which contained some meat, dairy, and eggs. What then?

Before offering my answer, it is worth considering the dialectical position many of the people who make the health based objection are in. In my experience, these are people who live in the United States. This means that they typically eat a diet that is loaded in refined sugars, chemical preservatives, saturated fats, and so on. In fact, as an undergrad, I once raised the health based objection to a more enlightened fellow philosophy student at Burger King. I was dining on a medium Whopper meal. That means I was drinking a quart of soda. In addition, I was consuming around half or more of my recommended daily fat intake. Let that sink in. I was like many others who make the health-based objection. Bacon cheeseburgers, snack cakes, and soda by the quart contribute to diabetes’ status as the seventh leading cause of death in the United States, not to mention its role in a host of other ailments.[5] Heart disease is the number one cause of death in the United States, and it is often a result of such a diet. There’s evidence which suggests that rates of cancer, the number two cause of death, is closely linked to the typical American diet. This diet also contributes to the soaring rate of obesity—somewhere over a third of the population is obese—and the associated healthcare costs of around $150 billion annually.[6]

Not only do individuals do this to themselves through their food choices, but they pass on these habits to their children.[7] Everyone who has tried to lose weight before knows how hard our gustatory habits can be to break. And the variation in gustatory preferences by culture indicates just how category- and habit-dependent such preferences are. So the typical proponent of the health based objection consumes a diet that quite literally shortens their lives, sometimes makes it difficult to engage in physical activity, drives up healthcare costs, and if they have children, significantly increases the chances that the children will suffer from this diet as well. And this is to say nothing of the “health” of the planet.

Do health-based-objectors really care about whether their diet will make them less healthy? Suppose the health-based-objectors are correct. This leaves us with two competing diets: eat animal based junk food despite its making us (far) less healthy, or eat vegan food despite its making us less healthy. Even if the objector is right, the typical American objector is still privileging their desire to eat junk food over their desire to not cause their own pain, suffering, and death (not to mention the animal’s desire to avoid pain, suffering, and death). The typical health-based-objector already chooses a diet that is seriously unhealthy; it is hard to take this as an objection made in good faith. I should emphasize that I’m not making a false dilemma, for needless to say, the health-based objection would be less absurd coming from those who do not eat a diet rich in animal fat and refined sugar. In what follows, I take on the objection as if it were being made in good faith by a carnist who is careful to eat a healthy diet which includes some meat.

Moving on, then, we can distinguish two types of creatures relevant to the discussion at hand: obligate carnivores and omnivores. I’ll discuss the health based objection to veganism with respect to each type.

Obligate Carnivores

Humans are not obligate carnivores. It might, then, seem like a waste of time to consider the health-based objection under the assumption that we are obligate carnivores. There are two reasons why I find this worthwhile. First, it raises an interesting question about the ethics of killing. Plausible accounts of the ethics of killing in self-defense all regard the killing of an unjust aggressor as morally permissible (given that the aggressor will act in such a way that it brings about the death or very serious harm of the innocent individual in question). They do not, however, unanimously regard the killing in self-defense of an innocent person posing a threat as morally permissible or even excusable. It is not obvious, then, that killing (and eating) another to preserve one’s life is morally permissible. This is to say that the ‘obligate carnivore’ defense of killing for food is not obviously successful. At least, more argumentation is needed. Given that the moral status of, say, a house cat, is comparable to the creatures it typically eats, this helps to substantiate Jeff McMahan’s controversial claim that it would be better to replace the carnivorous animals in the world with omnivorous or herbivorous animals (if it were possible without doing significant damage to the environment).[8]

The second reason considering the health-based objection under the supposition that we are obligate carnivores is worthwhile is this: if it’s not clear that we’re permitted to kill creatures with comparable moral status to preserve our own life, then it’s especially not clear how the health-based objection could work given that we arent obligate carnivores.

The literature on killing in self-defense is helpful in this context, for there we are concerned with the morality of killing (sometimes innocent) others in order to preserve our own life. We tend to think that killing in self-defense is permissible when the aggressor wrongly threatens one’s life. On the other hand, killing in self-defense is usually thought to be impermissible when the party subject to the lethal force is not liable for lethal force, as a result of not being an aggressor. For examples, consider Anscombe’s remarks:

[W]hat is required, for the people attacked to be non-innocent in the relevant sense [that is, liable to attack], is that they should themselves be engaged in an objectively unjust proceeding which the attacker has the right to make his concern; or—the commonest case—should be unjustly attacking him.[9]

And several of Jeff McMahan’s:

(a) [M]oral responsibility for an objectively unjustified threat to another is the basis of liability to defensive force…[10]

(b) [I]t seems clear that killing in self-defense is justified only in response to a limited range of serious threats—for example, when a person is threatened with being killed, tortured, raped, or kidnapped. One is not permitted to kill in response to lesser threats, even if the person who poses the threat satisfies all the other standard conditions for liability to self-defensive violence: for example, he intends the threatened harm, his action is unjustified, he is fully culpable, and so on. If, for example, someone maliciously threatens to give me a hard pinch and the only way I can prevent him from doing so is to kill him, I must submit to being pinched.[11]

(c) There is a strong moral presumption against causing harm. This is true even when it is inevitable that someone must suffer harm and shifting the harm from one person to another would reduce the amount of harm that must be suffered.[12]

Judith Jarvis Thomson, in her essay “Self-defense”, argues that it is permissible to kill “villainous aggressors” as well as “innocent aggressors,” but notes that some will deny that it is permissible to kill innocent aggressors, admitting only that it is excusable. What is important is that on the latter view what makes the killing excusable is that one is being threatened. Thus, on most accounts, killing an innocent person in self-defense is not impermissible only when the one being killed is an aggressor.[13] In almost all circumstances, killing a creature to eat it involves killing a non-aggressor.

Without getting into the intricacies of the doctrine of double effect, I’ll note that on some formulations, it (if correct) allows us to bring about the death of an innocent individual only if it is the foreseen but not intended consequence of bringing about some other good. Certainly preserving one’s life is good, but to kill an innocent individual for food is not merely a foreseen consequence. One has to act with the intention of killing the individual.

Common sense (and rigorous philosophical) thinking has it that killing an innocent non-aggressor to preserve one’s life does not count as permissible killing, and the DOD is no help here either. So, it’s at least not obvious that it’s permissible to kill innocent, non-aggressing individuals with similar moral status in order to preserve one’s life. (I haven’t argued for the claim that most animals have full or at least significant moral status here. I’ve assumed this given the dialectical position: recall that the health-based objection is typically raised after the case has been made for the moral status of most animals.)

Lifeboat cases are also relevant to the discussion here. Regan somewhat famously argued that in a crowded lifeboat, the dog ought to be thrown overboard rather than one of the other passengers (all persons). I think that this is right, but it doesn’t undermine the position I’m defending here. The reason is that we have a one-off case wherein the balance of interests clearly count in favor of the persons. This is not analogous to killing innocent creatures regularly for self-preservation. Additionally, some think that in the Dudley and Stephens case, in which, on the brink of starvation, they killed another for food, Dudley and Stephens acted permissibly. As is well known, they were charged with murder. So it is at least not obvious to many that self-preservation justifies killing an innocent individual. But for those who insist that Dudley and Stephens did act permissibly, I imagine that this is because it was another one-off situation. I strikes me as far less plausible to think that Dudley and Stephens could permissibly regularly kill members of the shipwrecked group. And if they did, this way of thinking is in clear tension with most accounts of the morality of killing innocent non-aggressors in war (which is an important part of just war theory).

Crucial to this discussion so far is the focus on killing an individual with similar moral status. As the disparity in moral status increases, the case for the permissibility of such killing becomes easier to make, but notice that this is true only in one-off scenarios.[14] Unless one thinks that there are creatures with infinitely higher moral status than others with at least some moral status (or that the numbers don’t matter when it comes to ethics), killing repeatedly to preserve one’s life is nonetheless not obviously morally permissible either.


Obligate carnivores need to eat meat in order to survive. We are omnivores, but most of us don’t need to consume animal products. Suppose, though, that animal products are required for optimal health. This is precisely the claim I’m granting on behalf of the health-based-objector. In light of the foregoing section, and considering McMahan’s plausible remarks about proportionality, it’s especially doubtful that it’s morally permissible to kill an individual with significant moral status in order to make one stronger, faster, or live slightly longer.

It is widely recognized that there are certain things we aren’t morally permitted to do in order to increase our health. The pursuit of optimal health does not give us moral carte blanche. Consider the following case:

Poison Ivy : Lisa practices homeopathy at home in order to keep her fatal cancer at bay, with the hope of living for an extra year. She has no reason to suspect that her homeopathic remedies do not work. She self-remedies with Rhus toxicodendron, which is derived from poison ivy. In order to make her Rhus toxicodendron, she has to bring poison ivy into her house. Unfortunately, she shares her house with someone who she knows is fatally allergic to poison ivy. Nevertheless, she brings poison ivy inside, and in her preparation of her remedy, exposes the roommate to poison ivy, resulting in her death.[15]

In Poison Ivy, Lisa kills another person. Given that she kills an innocent person not to save her life, but rather to extend it or make it more pleasant, she does something obviously wrong. Since the individual she kills has similar moral status, the health-based-objector will probably not find the case compelling unless they agree that persons and nonhuman animals have equal moral status. Consider, then, an appropriately modified case:

Dogs: Lisa practices homeopathy at home in order to keep her fatal cancer at bay, with the hope of living for an extra year. In order to create her remedy, Lisa needs to harvest the bone marrow of a dog killed by being boiled alive. Her treatment regimen requires that she doses daily. This requires the killing of one dog every 10 days, so Lisa kills 36 dogs per year.

I suspect most people will share my intuition that Lisa does something wrong in Dogs. The case is designed to resemble the number of animals killed per the typical American diet and to resemble the brutal way in which they’re often killed.[16] Of course, one important difference between Dogs and the situation the health-based-objector claims we are in is that the homeopathic remedy requires Lisa, we’ve supposed, to kill dogs for a year, whereas the meat eater kills a comparable number of animals each year for their entire life. If you fail to share my intuition in Dogs, if we adjust the number to take this into account, Lisa will kill over 2500 dogs (assuming she kills thirty-six dogs per year for seventy years). Outside of the context of one’s diet, then, health-based objections to the claim that one ought not to kill so-and-so (even if there is an asymmetry with respect to moral status) seem to fall flat.

Final Thoughts

I haven’t here relied on any controversial assumptions or arguments regarding the moral status of animals. I’ve pointed out that leading accounts of killing in self-defense imply that it is impermissible to kill an innocent, non-aggressing individual (with similar moral status) to preserve one’s own life. From there, I argued that it is unlikely that it is morally permissible to kill many individuals with significant (but lower than one’s own) moral status in order to marginally improve one’s health or longevity. This strikes me as a surprising conclusion. Prior to developing these arguments, I assumed that the health-based objection to veganism would be entirely successful if only the empirical component of the argument were true (and let me stress once more that it is not). Perhaps this says more about the accounts of killing in self-defense upon which I’ve relied than the health-based objection to veganism. I’m inclined to think, however, that it is more likely that the problem lies with the health-based objection than with the account of the morality of killing in self-defense, or killing for self-preservation more generally. Fortunately for us, we’re not obligate carnivores. I’ve also ignored a natural argument in favor of the view that it is permissible to kill individuals with a lower moral status than oneself in order to preserve one’s life: a straightforward act-utilitarian defense. I’ll say here only that, given the frequency with which we need to eat, I doubt that utilitarian calculations in fact support such a view. Surely the act-utilitarian’s utopia is inhabited only by vegetarians who find veggies delicious (or perhaps non-sentient and non-conscious meat machines).


[1] The success of such arguments, I should note, probably explains why a clear majority of ethicists regard eating the meat of mammals as morally wrong. See Rust, Joshua, and Eric Schwitzgebel. 2014. “The Moral Behavior of Ethicists and the Power of Reason,” in Advances in Experimental Moral Psychology. New York: Bloomsbury.

[2] I borrow the term “carnist” from psychologist Melanie Joy. Using the term “carnivore” to describe those of us who eat meat is straightforwardly mistaken.

[3] Campbell and Campbell, The China Study

[4] http://www.nfl.com/news/story/09000d5d82aeb668/article/arian-foster-on-vegan-diet-i-know-what-im-doing

[5] http://www.diabetes.org/diabetes-basics/statistics/?loc=superfooter

[6] http://www.cdc.gov/obesity/data/adult.html

[7] See this recipe for “butter and sketti” of Honey Boo Boo fame: http://www.foxnews.com/recipe/honey-boo-boos-sketti-3

[8] http://opinionator.blogs.nytimes.com/2010/09/19/the-meat-eaters/ and see also his response to the many silly objections raised in [surprise!] the comments section: http://opinionator.blogs.nytimes.com/2010/09/28/predators-a-response/

[9] Anscombe, “War and Murder,” p. 53

[10] McMahan, Killing in War p. 165-6

[11] McMahan, The Ethics of Killing, p. 399

[12] McMahan, “Self-Defense and the Problem of the Innocent Attacker,” p. 252

[13] See also Kaufman “Self-defense, innocent aggressors, and the duty of martyrdom.”

[14] See McMahan’s “Eating animals the nice way,” p. 70-71 for a discussion of the adding up and weighing of interests involved.

[15] Rhus toxicodendron is a homeopathic remedy, although I have no idea what it is actually intended to treat.

[16] Estimates of the number of animals killed per person per year vary significantly, from around 30 to up to 200, depending on whether we include shellfish.

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