Are Humans Omnivores?

You have probably seen some example of the multitude of posts around the internet arguing that it cannot be natural for humans to eat meat because we lack some characteristics possessed by all other meat eaters. This is a pretty weak form of argument, as can be made clear by this example:

Plants: Manufacture fructose
Animals: Do not manufacture fructose
Humans: Manufacture fructose

Plants: Are able to gather energy from the sun
Animals: Cannot gather energy from the sun
Humans: Are able to gather energy from the sun

There are two fallacies being used in this logic. The first fallacy is that of cherry picking. I have chosen only the data which confirms my conclusion that humans are plants. I have also cherry picked my definition of animals to include only the animals fitting the stereotypes I have defined. The second fallacy is guilt by association (which is itself an example of the fallacy of the undistributed middle). We have argued that all plants have some characteristic and all humans have the same characteristic and then tried to conclude from that fact that all humans are plants (although if we had a true dichotomy between being either animal or plant then actually showing that humans were not animals would be sufficient evidence to show that we were plants).

We can do better than simply pointing out that the logic behind this argument is flawed however, we can in most cases even explain why humans as traditional omnivores do not possess all these characteristics often possessed by other meat-eating species.

I have taken this post as a good example of the argument we are discussing.

Facial Muscles

CARNIVORE: Reduced to allow wide mouth gape
HERBIVORE: Well-developed
OMNIVORE: Reduced
HUMAN: Well-developed

Why are reduced facial muscles necessary for most meat eaters? The post even explains in the case of carnivores that it is in order to allow for a wide mouth gape. Some carnivores and omnivores hunt using their mouths as an important instrument in the kill. Humans do not use this method. We have historically used our hands in combination with tools in order to hunt and thus have never needed a wide mouth gape in order to hunt. This same explanation applies to why we have a seemingly herbivorous jaw type, jaw joint location, jaw motion, major jaw muscles, mouth opening versus head size, teeth of all types. There are still carnivorous and omnivorous species which do not hunt large prey with their mouths. Pigs are omnivores, eating leaves, grasses, roots, flowers, as well as insects and dead carcasses in the wild. Since their hunting style doesn't require them to kill large animals with their mouths they have facial structures very similar to our own in all of these areas.

Stomach Capacity

CARNIVORE: 60% to 70% of total volume of digestive tract
HERBIVORE: Less than 30% of total volume of digestive tract
OMNIVORE: 60% to 70% of total volume of digestive tract
HUMAN: 21% to 27% of total volume of digestive tract

Once again this applies to carnivorous and omnivorous species that hunt large prey. These animals often go for long periods between meals and then will consume a single large meal to survive on for long periods at a time. Most herbivores tend to graze throughout the day, not needing to hold a single large meal in their stomachs at once. Humans as animals that have evolved in small tribal settings have been able to share the meat of large kills with members of their community and have otherwise continued to typically eat several small meals throughout the day.

Colon

CARNIVORE: Simple, short and smooth
HERBIVORE: Long, complex; may be sacculated
OMNIVORE: Simple, short and smooth
HUMAN: Long, sacculated

Humans are along with all other primates in having sacculated colons. Ruminants are another group that tends to have sacculated colons. Sacculation of the colon in simple terms simply refers to the structure of tucks and pouches we find in our colon. In humans and primates this is thought to be a special adaptation to fermentation, allowing us to extract more energy from fiber.Source This adaptation would not be useful for carnivores who don't consume any significant amount of fiber. For other omnivores and many other herbivores they have likely all struck upon different solutions for improving digestion of fiber which doesn't require sacculation of the colon, much as many animals have evolved unique solutions to solving the problem of seeing.

Kidney

CARNIVORE: Extremely concentrated urine
HERBIVORE: Moderately concentrated urine
OMNIVORE: Extremely concentrated urine
HUMAN: Moderately concentrated urine

Animals with unconcentrated urine risk wasting too much water in order to excrete wastes through their urine. Animals with concentrated urine put themselves at higher risk of developing kidney stones and other kidney issues. Being a carnivore or herbivore has very little to do with striking this balance, while the prevalence of water plays a much larger role.

Nails

CARNIVORE: Sharp claws
HERBIVORE: Flattened nails or blunt hooves
OMNIVORE: Sharp claws
HUMAN: Flattened nails

Similar to facial structures, having sharp claws is only necessary if an animal is going to use these for hunting. Humans have never hunted using our nails and thus evolving sharp claws would be entirely unnecessary and quite a burden in our social lives. Once again omnivores like pigs or carnivores like anteaters do not have the features associated with their respective groups here.

Length of Small Intestine

CARNIVORE: 3 to 6 times body length
HERBIVORE: 10 to more than 12 times body length
OMNIVORE: 4 to 6 times body length
HUMAN: 10 to 11 times body length

This is not an accurate measure for omnivorous pigs whose, “small intestines have an average length of 15 to 20 m”Source. For those of you who aren't entirely familiar with the metric system a pig has a body length a little over one meter.

Why is this Important?

Anyone who is skeptical of veganism would see through this argument in a second. This is teeing them up to dismiss our arguments in an instant. Even more importantly however, we don't need this argument. Our recent ancestors have not been vegan, but the ethical reasons for being vegan still hold all the same. A well-planned vegan diet is still healthy during all stages of the life cycle. We don't need to use misleading claims to try to deceive omnivores when we have the truth on our side.

Friday Fallacy - If I could Kill it Myself

This week's Friday Fallacy post is going to be an example of an ignoratio elenchi or irrelevant conclusion fallacy. Ignoratio elenchi can be used to describe a broad group of logical fallacies all of which possess the characteristic that the conclusion of the logic does not address the issue in question. This specific example of an ignoratio elenchi argument is the argument that whether or not we should be able to eat meat should be determined by our ability to kill the animals ourselves. I have chosen to call this week's fallacy “If I could kill it myself”; although, a more appropriate name for the general fallacy might be “Appeal to personal ability”.

One omnivorous blogger writes:
“I have started to realize (partially due to moving back to Alaska recently) that if I can't look an animal in the face, kill it and butcher it...should I be eating meat at all?
If I can't do it myself, I expose myself as a hypocrite, because I would rather have someone else do the 'yucky stuff' and I get to reap the benefits.”

A second omnivorous blogger seems to have put themselves through quite a bit of trauma trying to kill an animal in order to prove a point.
“I’ve spent a lot of words in recent posts explaining why I need to know where the animals come from that I eat, but standing there in the brutal sun, feeling like the earth was tilting under my feet and hearing a strange roar in my ears I questioned why this was so important. I felt quite as if I may pass out or possibly throw up at any moment, so why subject myself to this? I wish I could explain eloquently but I can’t. I only knew that if I’m going to eat meat, this was something I had to do. If animals can lose their lives for my dinner, I just needed to feel that I paid my own price, that of feeling the pain of taking one’s life.”

This is not a thought process unique to omnivores trying to justify their own actions as this vegan commenter makes clear:
“One big reason I quit eating meat in the first place was because I realized that I myself could never go out and kill another living thing, so why would I be okay with eating something someone else has bludgeoned to death?”

While our ability to kill an animal may speak to our personal squeamishness and, in the second example given above, personal resolve, it says nothing about whether the action is one we ought to do. If the simple fact that people had the ability to do things justified doing them, then we would have no grounds upon which to call any action unethical. Clearly (Modus Tollendo Tollens) our disagreement with this conclusion speaks to the fact that we do not hold this logic to be sound.

Friday Fallacy – Illicit Minor

If you have not yet read last week's fallacy on the fallacy of the undistributed middle read that first, as this week's post will only make sense in light of that post.

Like the fallacy of the undistributed middle, illicit minor is also a syllogistic fallacy, and the form is fairly similar. The fallacy of the undistributed middle had the form:

All A are B;
All C are B;
Therefore, all C are A.

Illicit minor has the form:

All A are B;
All A are C;
Therefore, all C are B.

For example:

All animal rights activists are vegans;
All animal rights activists are humans;
Therefore, all humans are vegans.

As pleasant as this conclusion is, we clearly have yet to make it true. In a syllogism, the categorical proposition with the term that comes second in the conclusion, in this case, “all animal rights activists are humans,” is called the major premise, and the categorical proposition with the term that comes first in the conclusion, in this case, “all animal rights activists are vegans,” is called the minor premise. This syllogism is a fallacy because the minor term allows some humans to still not be animal rights activists, yet our conclusion tries to draw from the animal rights activist property of humans in order to draw its conclusion. The name illicit minor derives from the fact that the minor premise does not describe all of the individuals who are described as the subject in the conclusion.

It is still possible for syllogisms of this form to have true conclusions. One example might be:

All cats are animals
All cats are mammals
Therefore, all mammals are animals.

This conclusion is technically true, but it cannot be derived from the two premises given. The fact that the conclusion does not necessarily follow from the premises is what makes an argument a fallacy, not that it is necessarily false.

You may have noticed that last week's fallacy was a bit sparse on the examples. That is because most good examples of syllogistic fallacies are actually cases of illicit minor. Remember that things like “I am an animal rights activist” is the syllogistic equivalent of “All 'me' are animal rights activists.” Here are a few examples of illicit minor in action:

The book The China Study cites studies where animals fed diets high in casein developed certain cancers at a much higher rate than those fed other diets. Casein is an animal protein. We cannot conclude from this, as the China Study attempts to do, that all diets high in animal protein will lead to higher rates of those cancers.

Roundup ready crops may contain unsafe levels of pesticide residue. Roundup ready crops are genetically modified. We cannot conclude from this that all genetically modified crops are necessarily unsafe even if Roundup ready ones are.

All of my blog's readers are becoming more skeptical. All of my blog's readers are or are becoming vegan. Sadly, this doesn't mean that all people who are or are becoming vegan are also becoming more skeptical.

Keep fighting the good fight for rights and reason everyone! More fallacies are on their way.

Friday Fallacy – Fallacy of the Undistributed Middle

The fallacy of the undistributed middle is a form of syllogistic fallacy. Syllogisms consist of three categorical propositions, two assumptions and a conclusion, which are statements of the form (all, some,or none) (items in category A) (are or are not) (items in category B). For example, “all dogs are animals,” would be an example of a categorical proposition. If we combine this with the categorical proposition, “all poodles are dogs,” we can conclude from these two assumptions that, “all poodles are animals.” The logic we have used to make this conclusion is known as syllogistic logic. Here is another example:

No vegans eat meat;
Some raw foodists are vegan;
Therefore, some raw foodists do not eat meat.

If we accept that the first two assumptions are true, then it necessarily follows from those assumptions that the conclusion, some raw foodists do not eat meat, is true as well. There are a limited number of forms syllogistic statements can take. All vegans are not people who eat meat, is the same as saying no vegans eat meat, and vice versa, so there are in actuality 4 different forms a categorical proposition can take and a syllogism consists of 3 individual categorical propositions, so there are 4^3 or 256 possible forms a syllogism can take. Not all of these forms result in conclusions that are always true. For example:

Some raw foodists are vegan;
Some meat eaters are raw foodists;
Therefore, some meat eaters are vegan.

While both of the assumptions above are true, the conclusion is clearly false. Up to this point we have kept the three different categories being used in the syllogism in the same order, but the order can move around so long as three different categories are introduced in the two assumptions, the category that repeats does not repeat in the same assumption, and the conclusion incorporates the two categories that had not yet repeated. For example:

All dogs have tails;
I do not have a tail;
Therefore, I am not a dog.

In this case, the categories, dogs, (things that) have tails, and me, appear in a different order, but in this case we still have a syllogism which (if we accept the premises) yields a conclusion which is necessarily true. Changing the order in which the categories appear does change which syllogisms work and which do not.

Syllogistic logic is something you likely do every day without being consciously aware of it. Notice that statements like, “If someone is vegan then they do not eat meat,” means the same thing as, “all vegans are people who do not eat meat.” The fallacy of the undistributed middle is an example of a syllogism that does not work. It takes the form:

All A are B;
All C are B;
Therefore, all C are A.

or

All A are B;
Some C are B;
Therefore, Some C are A.

For example:

All fruitarians are vegan;
I am a vegan;
Therefore, I am a fruitarian.

In this case the two assumptions may both be true, but the conclusion does not necessarily follow from the assumptions (I assure you that I am not a fruitarian). In this instance it is easy to see that the logic is flawed, but when we incorporate this logic into everyday speech it becomes more difficult to see:

If someone is vegetarian then they never eat meat,
Bob never eats meat,
Therefore, Bob is vegetarian.

In this case the conclusion is necessarily true, but the reason why is unclear. When we said, “if someone is a vegetarian then they never eat meat,” we also meant to imply, “if someone never eats meat, then they are a vegetarian.” This extra assumption can then be used to form a valid syllogism. Sometimes when we use the “if” statement it doesn't work this way:

If someone wears fur, then they do not care about animal rights;
Bob does not care about animal rights;
Therefore, Bob wears fur.

The conclusion that Bob wears fur does not necessarily follow from the assumptions because in this case we did not imply that everyone who doesn't care about animal rights also wears fur.

Here is an example were this may come up in reality.

If someone eats too much meat then they are going to be unhealthy. Bob is unhealthy. We cannot immediately assume that Bob is eating too much meat and that is the source of his poor health.

Check out next week's fallacy, illicit minor.