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The “Appeal to Nature” fallacy comes up frequently in debates about the rights or wrongs of human diet. It is used by those on both sides, but what is it, is it valid, and what light can it shed on the ethics of our dietary choices?
“Appeal to Nature” is a logical fallacy (i.e. a refutable logical mistake) that can be summed up as,
1) Because X is found in Nature, it’s therefore good / justified / healthy / valid… etc.
There’s also a corresponding flip-side:
2) Because Y is not natural, therefore it isn’t good / justified / healthy / valid… etc..
Yes, absolutely. It’s a very common mistake, and it’s easy to show why it’s a mistake.
In the first pattern (1) there are plenty of things that are natural but not very good or healthy. For example, all natural disasters are by definition both natural (yay!) and disastrous (boo!). Or take the fact that many dominant male animals will kill the offspring of competitors, or the way that drakes will competitively gang-rape ducks and injure, blind, or drown them in the process.
Likewise, there are plenty of things that are very virtuous in the human world (assuming human technology is not natural), such as toothbrushes, the Hubble telescope, or defibrillators.
So yes, Appeal to Nature is a thing.
Ah, now things get funky. We can actually break this down using the three common pillars of the diet debate:
Let’s look at each of these in turn, from both sides of the fence.
Omnivore 1: “Eating meat/animal products is healthy for us, because it’s natural.”
Vegan 1: “Eating plants is healthy for us, because it’s natural.”
First of all, it depends on your perspective of what’s natural, i.e. what did our ancestors eat? There are some vegans who feel the need to argue that humans have evolved as herbivores or frugivores, and therefore have never needed meat or animal products in their diets. I believe that the science shows that position is conclusively wrong.
Let’s summarise the scientific case very briefly. Our earliest ancestors were almost certainly primarily plant-eaters, like chimpanzees and bonobos. (Chimps will actually hunt for meat when given the opportunity, but we’ll leave that aside for now.)
We since evolved to eat meat, using our intelligence and opposable thumbs to our advantage. That gave us the ability to make weapons to hunt, tools that let us carve meat and crack into the crania of prey to access highly nutritious brain offal, and also fire that released more nutrients and energy from the food.
So while our physiology does not appear to be too similar to a bear’s or pig’s (we don’t have big-ass canine teeth, for example), that’s because our technological tools meant we didn’t need those physiological tools. Additionally, our intestinal tract is much shorter than, say, a gorilla’s, because we no longer need to digest all that plant cellulose.
For the full breakdown, look no further than this vegan PhD biologist’s excellent article: “Humans are not herbivores”.
Okay, so if our more recent ancestors evolved eating meat, shellfish, and brains, what does that mean? Does the fact that they ate that stuff mean it’s right or natural or healthy for us to eat the same? Or is that an example of Appeal to Nature?
To a degree, I believe it gives some weight to the modern omnivore argument. If it was good enough health-wise for Ogg the caveman, and those cavepeople survived long enough to spawn almost eight billion more like them, then clearly it didn’t do them any harm evolutionarily.
However, it does not extend to mean that the Paleo diet Ugg ate is necessarily optimal for us today. Not because we have evolved significantly enough away from Ugg (there just hasn’t been enough time for that), but you might argue that it’s not optimal if a healthier diet is available to modern humans that was not available to Ugg and his crew.
It’s conceivable that we might develop the technology to grow a new type of alga in sunlight that provides all the amino acids, fatty acids, vitamins, and minerals that our bodies need. Let’s also say for now that it’s also conceivable that there’s a plant-only diet that could do the same for every human being on the planet.
But the question we’re asking is not whether meat and animal products offer the healthiest possible option, but whether they’re healthy. The latest scientific literature on the subject is divided, although less so than it has been in the past couple of generations, as there is lots of evidence coming to light that refutes the stigma against meat and animal fats that have been mainstream for a few decades.
I don’t have the space to attempt to summarise the whole health argument here, and anyway this article (with plenty of links) from Chris Kesser gives an awesome up-to-date overview.
So who takes the points from Round 1, and does either our vegan or omnivore protagonist fall foul of the Appeal to Nature fallacy?
I don’t think either the omnivore or vegan necessarily falls into Appeal to Nature here. The vegan clearly doesn’t because their premise (“Everyone can live perfectly healthily on a plant-only diet”) is already demonstrably false. I will leave open the possibility that some people may be able to thrive long-term on a plant-based diet, but the more stories I read the slimmer I perceive that possibility. It is apparent that for many people, eating plant-based has proven disastrous to health.
The omnivore argument could be accused of appealing to nature — if made in isolation, i.e. “It’s natural, therefore it’s healthy.” But because it is also demonstrably healthy in its own right, there is clearly a valid connection between naturalness and healthiness. If the evidence were weighted on the side of the plant-based diet, then the tables would be turned.
I must also stress that the argument “It’s healthy to eat meat” does not necessarily extend to include all meat. Factory-farmed animals that are fed unnatural diets (e.g. giving large amounts of grains to ruminants), fed hormones to promote growth, kept in confined conditions that promote disease, and bred to reach market weight as quickly as possible, do not necessarily provide meat that I could stamp as “healthy”. Likewise, a standard Western diet that comprises processed meat and “grocery items” made in factories is clearly not good for human consumption.
Omnivore 2: “Eating meat/animal products is ethical, because it’s natural.”
Vegan 2: “Eating meat/animal products is unethical, because it’s unnatural.”
At face value, there are two sides to this argument. The first is whether it’s natural for humans to kill for food; the second is whether it is natural for certain animals to be killed for food.
I am convinced that both are true: humans evolved as hunters and fishermen; and it is natural not just for some species to be prey, but ultimately for all living things to be consumed by other living things. I have written about this at more length previously.
However, even if both are natural, does that argument from the omnivore fall into Appeal to Nature? And does the opposite position risk the same for the vegan?
As before, I don’t think the vegan argument gets that far. It clearly is natural for a species that evolved as an apex predator to predate, and it’s natural for a species that evolved as, or has been bred from, a natural prey animal to be prey to predators. But that’s not what we’re investigating here.
I am personally of the view that the omnivore’s argument, again taken in isolation, could indeed fall foul of Appeal to Nature.
Many vegans have argued to me that to take the life of another being that doesn’t want to die, and which can experience fear and distress, is cruel, and therefore unethical and wrong.
Now, for them to argue that it’s wrong because it’s not the natural way of things for humans and/or beasts would be faulty logic. But there’s a valid argument to say that if it’s unnecessary and causes suffering to another living being, then it’s insupportable.
And I would agree. I think they’re right. If it’s unnecessary and causes needless suffering, if it’s only for the pleasure of my tastebuds, then I don’t think I could slaughter an animal for food.
Unnecessary? We have already established that, at least for some people, it is not an option to exclude meat and animal products. Many humans cannot survive without animal products, and many more cannot be fully healthy.
Needless suffering? If consuming meat and/or animal products is necessary, as I believe it is, then we may discard the word “needless”, but we should certainly focus our attention to minimising any suffering an animal goes through in any of these processes!
I will say outright that I am firmly against industrial-scale slaughter. I think these factories must be terrifying to the animals, and that suffering can clearly be avoided by reversing the recent trend and going back to localised, small-scale slaughter.
We should also compare the quality of a farmed animal’s life and death with its equivalent in the wild. If you consider how most animals meet their ends in Nature, whether it is by predation, accident, fighting, disease or parasites, drought, or starvation, even the (preventable) horrors of an industrial slaughterhouse begin to seem pale in comparison.
Many of those horrible “natural” deaths can be prevented by good husbandry. Farmers provide the animals in their care with protection, shelter, food and water in all seasons, veterinary care, and (ideally) a stress-free and painless death — just as any pet would enjoy. One could even use the same argument: that, if we have the power to protect animals from needless suffering through management, we have a responsibility to do so.
So is keeping and/or killing animals for our food justified because it’s natural? No, not solely on that score. (And you could argue that husbandry is a better option for the animal.) Additionally, a better-welfare option would have to present itself for the counterargument to be more valid.
Omnivore 3: “Eating meat/animal products is good for the environment, because it’s natural.”
Vegan 3: “Eating plants is better for the environment, because it’s natural.”
Either of these arguments could fall into Appeal to Nature, if made in isolation. And each could easily be countered, because the way that nearly all our food is grown, in the Western world at least, is so unnatural that it nullifies the Nature argument.
Industrial animal farming is an abomination, and so is industrial-scale arable farming. Neither is sustainable, both result in massive pollution and depletion of the precious topsoil that sustains practically all human life.
We have to restrict any discussion to sustainable methods of growing food, which might include hunting and fishing for wild meat, mixed animal/plant farming, small-scale family farming, silvopasture, veganic agriculture (which has its problems, but may be considered sustainable, if not optimal), and of course permanent grazing on pasture.
However, when it comes to using “because it’s natural”, we have to define “natural” and then we get drawn into two questions:
Is arable agriculture natural? We didn’t use to do it, then we started doing it manually, then with draft animals, now with ever-bigger machines.
Is herding animals natural? We didn’t use to do it, then we started doing it with the help of domesticated wolves and makeshift fences, now we do it with feedlots and imported grains and soy husks.
I do not propose to answer any of these questions, because they’re all redundant. On reflection, both the animal and plant arguments could easily fall into Appeal to Nature. Yes, it’s natural to eat meat, fish, and other animal products. Yes, it’s natural to eat plants. It may be natural (for some groups or individuals) to evolve culturally to eat only plants. But none of those arguments can stand on its own feet to merit the claim “good for the environment”, because it all depends on the how.
You would be fully justified in asking, “Why does the first Omnivore argument (eating meat/animal products is healthy because it’s natural) not fall into Appeal to Nature, but these arguments (eating either animals/plants is good for the environment, because it’s natural) could fall into Appeal to Nature, when both may or may not result?”
The first argument stands up because there is an evolutionary link between the historical naturalness of eating meat and animal products and the present-day healthiness of eating meat and animal products. And of course there are caveats. It does not stand that all meat is necessarily healthy.
However, is there any similar link between our eating plants / animal products and any benefit to the environment? If applied to the whole animal kingdom, it does stand up, because if animals eat plants and other animals, they provide several important components within an ecosystem (including removing weak or diseased organisms, recycling and moving nutrients around the place, and accelerating decomposition).
But, taking the natural world as a whole, humans would not seem to be an essential component. If we — and our food systems —were wiped out tomorrow, the natural world wouldn’t blink. In fact it would probably immediately be better off. Other organisms would quickly move in to fill our niches, and life carries on.
However, there’s a catch. Because we are here, and we do currently manage the majority of the Earth’s land.
That means, over all that area, we are by default the apex predator. And, as we know, in all of Nature’s wondrously complex and interconnected ecosystems, those top predators occupy a key role. Because in much of the world we’ve simply wiped them out, the role falls to us.
So with humans managing the land, but without humans raising ruminants (in particular), Nature would suffer, because there would be a lack of large animals grazing the grasses, forbs, and trees, depositing their waste products, and helping trample the dead matter onto the ground. The biological machine would turn, but would turn more slowly, resulting in a slowing down of the cycle of life. Life would still continue, but I couldn’t make the argument that the environment would be improved.
That means, as things stand, and acknowledging that the way we produce much of our food, whether animal or plant-based, is still detrimental to the environment, it is still valid to argue that eating meat and animal products provides an important environmental role.
Surprisingly, I cannot say the same for eating plants! I cannot come up with an argument to justify the claim that humans eating plants benefits the environment.
This is a topic that clearly merits more thought, and which I am sure I will revisit after further discussion.