Skeptical veganism

Since I started this blog it’s became more and more apparent that there is a need for an increased skepticism and a scientific approach to veganism.

In the best of worlds, the following post wouldn’t be needed.

The importance of truth

First of all, science does not deal with absolute truths. I usually claim that it’s only the religious and mathematicians that deal with truths. However, science is the method that we use to acquire knowledge about the world and how it works. How does gravity work? How does a cell work? What are the mechanisms that lead to cancer? These are all scientific question. In contrast, questions that aren’t scientific questions include if it is morally correct to eat meat? What is the meaning of life? Which color is the most beautiful?

Science cannot tell us objectively how we should behave or live our lives, but science can provide facts about the world, from which we use reason to argue in the realm of subjectivity. For example, science has provided us with a fact – “smoking increases the risk to develop certain cancers”. I could reason that I shouldn’t smoke and use this fact as a basis for my argument. The argument should include some reasoning around the facts such as that I want to avoid cancer and I think avoiding smoking is not a loss but only a gain to me. Science doesn’t tell us objectively that we shouldn’t smoke, but it provides us with information on which to base our decisions.

Using science to support one’s claim is not wrong, but it has to be accompanied with reasoning. Using scientific facts, as the sole component of an argument is virtually always a fallacy, in the context of biology and veganism – almost always appeal to nature.

For me personally, I’m interested in how the universe works, and more specifically living things. For this reason I don’t want to waste my time on things that aren’t true. History has shown that science is the best method that leads to knowledge – it works, science works, and we see it over and over. That alone, is an argument to stick to the facts that is supported by science.

The second reason to keep to facts that actually are based in science is that an argument that is based on a claim about the universe is weakened if the supporting claim is proven false. If I argue that one should be vegan because animals are able to feel pain and therefore suffer when slaughtered and bred for food, and it’s not ethical to impose suffering on others. Then I rely on that the factual claim – that animals are able to feel pain – is true. If it would be false, my argument would fall if it only supported by that single fact.

The issue 

That strong and good arguments are based on sound reasoning and supported by scientific facts or evidence should be quite obvious. However, I write this because unfortunately this is not how people argue and specially not when arguing for veganism.

I’d like to exemplify the issue with some tendencies I’ve seen too many times.

The environment and the health 

Veganism is about animal rights. It’s a strive to minimize the  one’s contribution to animal suffering.

However, some people mainly –  or almost exclusively – argue for veganism based on environment and health. First of all, I would assume that it would only apply to diet – veganism is much more than that. Since, I’ve never seen an argument to avoid leather for health reasons.

Being vegan based on environment or for health reasons relies on the fact that a vegan diet is the most healthy diet and that veganism is always better for the environment than not being vegan.
When it comes to the environmental impact of diets, the main reason that a western meat-eating diet is problematic is specifically cattle – beef and bovine dairy (Steinfeld, Gerber, Wassenaar, Castel, & Mauricio Cees de Haan, 2006; Weber & Matthews, 2008). An environmental friendly diet is not guaranteed to be free from animal suffering. The type of animals and how they are farmed have quite a big impact on each calories environmental cost. Also, it could be the case that the environmental impact of animal farming is reduced to acceptable levels by technological advances in the future. Should people still not be vegans if that happens? I’m not saying that a vegan diet now, on average, isn’t more environmental friendly than an average western meat-based diet, but it’s a weak argument since it’s not necessarily always true.

Similarly, the argument based on health is also quite weak. My appreciation of the literature is that it’s not very convincing that a vegan diet is always healthier than a non-vegan diet. I would assume that most people would agree that it’s certainly possible to not be healthy on a vegan diet.

For most people I think that being “healthy enough” is what matters. Many people who argue for health primarily, have a very sect-like idea that everyone would strive to optimize their health to great length, with very small margins. If it’s possible to be relatively healthy by including meat in moderation in one’s diet, then health is also a very weak argument for veganism.

Just as an example, one proposed reason that processed meat and read meat now is on WHO’s lists of known carcinogens is because of nitrates (Chan et al., 2011; Honikel, 2008; IARC, 2015; Joosen et al., 2009). People arguing from a health perspective usually bring up this fact (see my post). But, fear-mongering about this, is not at all certain to avert people from eating meat, it could like-wise just promote for example development of processed meat, without such preservative agents that are less harmful or otherwise minimizing the carcinogenic compounds.

Appeal to nature

I’ve already written a post about this. Appeal to nature is simply the fallacy that things that are natural are good and therefore “natural” things should be preferred over “unnatural” things. This is obviously not true, modern medicine is a clear example of this.

One example of appeal to nature that meat-eaters sometimes use is the claim that eating meat is natural and therefore good, or at least not wrong. The easy and arguably the correct way to refute this, is to point out that the argument is based on appeal to nature. However, what too often happens is that people don’t point out that simple fact; instead they’ll try to argue that humans are natural herbivores. Ergo, countering an appeal to nature with an appeal to nature.

The meat-eaters argument is based on a scientific fact, humans are omnivores, but the argument is flawed since it assumes that diets are prescriptive and not descriptive. And again, it’s appeal to nature. The counter-claim that humans are herbivores is in fact not true (see my post humans are not herbivores). But it will seem like the meat-eater “won”, when actually both used flawed arguments.

In an attempt to win the argument, people turn to questionable sources to back their false claim. Then, one creates the impression that veganism is an irrational idea since people have to twist facts and turn to pseudoscience to argue for veganism. Since, anyone capable of looking up “omnivore” or “human” in a basic biology textbook or dictionary would see that the consensus is that humans are omnivores – which of course, has no meaning to whether one should be vegan or not.

Scientific facts are completely neutral.

The opinioned fact

The even more absurd tendency I’ve observed is the idea that scientific facts are a matter of opinion. It’s not an opinion that the earth is spherical and not flat, it’s a fact completely regardless of anyone’s opinion. How this can be so common is still an enigma to me.

A fundamental assumption about realty is that we all live in the same universe and experiences the same universe, so two completely contradicting facts cannot be true at the same time, just like with the shape of the earth. Yet, some people cling to the idea that it’s a subject of opinion. Surely, in a controversial field where substantial contradictory evidence exist, one can have a discussion about what model that is more likely describe reality the best. This is very rare outside the academic world though. What I’m talking about here is a well-established facts being questioned with merely an opinion.

This makes of course a very poor argument and is again undermining the rational case for veganism.

I’ve come to notice that some people think that a set of delusions follows a particular ideology or philosophy. As a vegan it’s almost expected to believe that humans are herbivores, meat is deadly toxin comparable to arsenic and that meat-eaters should believe the opposite. This is all of course nonsense and there is absolutely no reason to not stick to what is true and still argue for veganism. I don’t think I’m alone experiencing a lot of vegans just assuming that everyone in the community by default shares deluded ideas that stereotypically vegans believe. It has to stop.

Oh, the frustration.

I don’t really know where it started, but the arguing and counter-arguing based on fallacies just keeps legitimizing nonsense as valid arguments, which really won’t convince anyone with some critical thinking.

I can understand that in the face of the horrendous animal abuse, people want a quick change. Thus, compelled to over-exaggerate to make a more convincing argument for a quicker change. But, the exaggerated claim will be less convincing to someone who is not ignorant and make it even harder in the long-term to make the transition to a world free of animal abuse.

It’s very frustrating to see that people use pseudoscience, myths and just plain lies to argue for veganism when we have so many good arguments to be vegan. I’ve written a post trying to argue from an ethics perspective.

With the rising interest about veganism we could perhaps  start getting rid of the classical stereotype of an irrational pseudoscience vegan and actually show the rational ethical side of things. Not only because I think it benefits the animals in the long run, but also, pseudoscience is really a threat to society.


Chan, D. S. M., Lau, R., Aune, D., Vieira, R., Greenwood, D. C., Kampman, E., … Dorant, E. (2011). Red and Processed Meat and Colorectal Cancer Incidence: Meta-Analysis of Prospective Studies. PLoS ONE, 6(6), e20456.

Honikel, K.-O. (2008). The use and control of nitrate and nitrite for the processing of meat products. Meat Science, 78(1), 68–76.

IARC. (2015). IARC Monographs evaluate consumption of red meat and processed meat.

Joosen, A. M. C. P., Kuhnle, G. G. C., Aspinall, S. M., Barrow, T. M., Lecommandeur, E., Azqueta, A., … Bingham, S. A. (2009). Effect of processed and red meat on endogenous nitrosation and DNA damage. Carcinogenesis, 30(8), 1402–7.

Steinfeld, H., Gerber, P., Wassenaar, T., Castel, V., & Mauricio Cees de Haan, R. (2006). Livestock’s Long Shadow. Food and Agriculture Organization of the United Nations.

Weber, C. L., & Matthews, H. S. (2008). Food-Miles and the Relative Climate Impacts of Food Choices in the United States. Environmental Science & Technology, 42(10), 3508–3513.



11 thoughts on “Skeptical veganism

    1. That is you. What’s worse than obnoxious meat-eaters? Ignorant pseudoscience pushing vegans.

      You have the best vegan blog, hands down. Thank you.


      1. So, though I’m an ethics oriented, local farmer grandpa, I’m an obnoxious meat-eater? That’s not how we move forward, Oh, and my son followed in my footsteps as an environmental and evolutionary biologist too.


  1. I just found your blog and as a vegan biologist as well I really like it! I hope you write more, and I wanted to ask your permition to translate this article to brazilian portuguese?


  2. You made some good points, and gave me information I wasn’t aware of, so thank you for that. Also there was some subjectivity that leaked in and sullied the value of your post. You claimed the health argument was weak but offered no reasoning on this, in fact you only gave one example of how red and processed meat was bad for you, because of the nitrates.

    Also the following statement made little sense:

    “I’m not saying that a vegan diet now, on average, isn’t more environmental friendly than an average western meat-based diet, but it’s a weak argument since it’s not necessarily always true.”

    There’s a lot of things that “aren’t necessarily always true,” that are still relatively true. Like you said, science doesn’t deal with absolute truths, the point is to give facts within context of their observation. You could say “some people say smoking is bad for you because it causes cancer, but this is a weak argument since it’s not necessarily always true.”

    I would have preferred you shared some statistics on the energy and water required to raise an animal for slaughter vs. various plants. As well, the ecological damage contrast from raising animals to growing plants; things like methane emissions vs the destruction of forestry for consumable plants (while considering how many of those plants, or grains, are going to feed farm animals).

    I specifically point to this as being of note: “The 400-page report by the Food and Agricultural Organisation, entitled Livestock’s Long Shadow, also surveys the damage done by sheep, chickens, pigs and goats. But in almost every case, the world’s 1.5 billion cattle are most to blame. Livestock are responsible for 18 per cent of the greenhouse gases that cause global warming, more than cars, planes and all other forms of transport put together.

    Burning fuel to produce fertiliser to grow feed, to produce meat and to transport it – and clearing vegetation for grazing – produces 9 per cent of all emissions of carbon dioxide, the most common greenhouse gas. And their wind and manure emit more than one third of emissions of another, methane, which warms the world 20 times faster than carbon dioxide.”

    The report goes on to list a plethora of other negative environmental factors ranging from coral reef destruction to degradation of drinking water quality, and even deforestation due to ranching being cited as “the major driver of deforestation.”


    1. On the part about methane though, that falls under the “Not always going to be true” section.

      Not only are bio-gas plants becoming a thing now (Not ideal, but still better than without) We also have methane cracking research coming up fast which produces hydrogen from methane without the release of CO2.

      CO2 itself is on the top shelf of a lot of peoples minds for cutting down. We have hit somewhat of a plateau after a very rapid rise. China especially, the biggest producer has finally been taking steps to address it at least somewhat. With other tech like renewable energy, better power grid tech (like battery banks), non-petrol cars, and systems to sequester CO2 to produce other products (including fertilizer), it is likely CO2 levels will start to roll down off the plateau and sink again. So CO2 will very likely eventually also fall into “no longer true”


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