The fallacy of composition is an informal fallacy that occurs when a false conclusion is made about the whole of something based on the characteristics of some or all of its parts.
An argument that commits this fallacy makes the mistake of assuming that the parts which make up this whole will be the same as the whole itself.
Consider the following;
- The parts of something do not necessarily have the same characteristics as the whole itself.
- Often, the characteristics of the whole will be different to the individual characteristics of the parts of that whole.
Sometimes the parts and the whole will share the same characteristics, however, the point is that it is fallacious to assume that the parts and the whole are the same just based on the characteristics of the parts.
The opposite of the fallacy of composition is the fallacy of division.
- One bird is quiet so a flock of birds will be quiet.
- A domestic cat likes to be petted so a tiger would, too. It’s just a cat.
- All logical fallacies are the same. I understand one type of logical fallacy, so I understand all types of logical fallacy.
- Reading the first chapter of a book and assuming the book must be bad because the first chapter is not great.
- The 20th century will be remembered as a century of suffering and war.
- Assuming an archaeologist’s job is full of adventure because sometimes they do digs.
- An atom is almost weightless. A brick is made up of atoms. So, a brick will be light.
- It’s so easy to tear paper and a phonebook is made up of sheets of paper. So, I could tear a phone book.
- When you look up at the night sky, it’s nearly all blackness. Space is practically empty, so there’s not much going on up there.
- Water from the tap doesn’t have much pressure, so surely the bottom of the ocean must not be full of pressure either.
- I got into a car crash and the person at fault was a woman. It seems like women are bad drivers (see also: gender stereotypes).
- I have a friend who is a Scorpio and he’s ambitious and fiercely loyal. All Scorpios (people born between October 23 and November 21) must be like this.
- When I was a child, my neighbor’s dog was aggressive. I have grown up to assume that all dogs are aggressive.
- I travelled to Bali and met some really unfriendly people. I now think Balinese people are unfriendly and wouldn’t go back (see also: ecological fallacy).
- Venezuela is a dictatorship without a functioning democracy. The people of Venezela must hate democracy.
Some Examples Explained in Detail
1. a flock of birds will be quiet
One bird may be quiet and graceful as it flies overhead, but a flock of 200 birds would be noisy and chaotic.
To assume that a flock of birds would be quiet, just because a single bird is quiet would be committing the fallacy of composition.
The assumption is based on the characteristics of one bird – a part of the whole – and is applied to the whole flock of birds.
2. A Tiger is just a Big Cat
Mark is at a petting zoo. Under the supervision of an animal handler, the public is allowed to pet a cheetah. He says to his friend that he is a real cat lover and has 3 cats at home so he knows how to handle them.
His friend tells him to be careful, a cheetah is not the same as a house cat. He should be careful when petting it. Mark ignores his friend’s advice and almost gets bitten by the cheetah.
Mark’s careless actions with the cheetah were caused by his belief that a cheetah is the same as a house cat. He got this belief because house cats and cheetahs are both part of te cat family. Mark therefore believed that he could treat the cheetah as he would one of his cats.
By doing this he is committing the fallacy of composition. Mark assumed that the characteristics of a house cat would transfer to the larger cat family just because they are part of the same animal family.
3. All logical fallacies are the same
Zahra, a first year philosophy student, learns about the fallacy of composition. In the lecture she learns that it is a type of informal logical fallacy.
Later on in the week, her friends are talking about a different type of logical fallacy. Zahra assumes that it has the same structure as the fallacy of composition and explains this to her friends. Zahra is committing the fallacy of composition by assuming this.
Zahra assumes that because one type of logical fallacy has a certain structure, so do all the rest. She is assuming that the characteristics of one logical fallacy automatically transfer to the whole group.
4. Judging a book by its cover
Caroline reads the first chapter of a best-seller novel. It is violent and not at all to her liking. She is disappointed and can’t see what is so great about it.
Caroline is committing the fallacy of composition. She assumes that the whole book is violent and will not be to her liking, just because the first chapter is violent.
5. The 20th century was a century of suffering
A professor is giving a speech about the character of the 20th century, that it was 100 years of war and the consequent suffering that this entailed.
The professor is committing the fallacy of composition by making this claim. While it is true that large parts of the 20th century were taken up with wars, that does not mean that the century as a whole is one of war and suffering.
The 20th century was also a time of unrivaled scientific, artistic and social progress. The wars were just one part of the whole. It is a fallacy of composition to apply the characteristics of this one part of the century to the whole century without further analysis.
6. archaeology is full of adventure
Darius loves adventure, history, and exploring new places. He decides he wants to be an archaeologist because they are always out exploring and discovering ancient ruins in exotic places.
His friend informs him that that is only a small part of what some archeologists do. Much of their work is research and time spent in laboratories.
Darius committed the composition fallacy as he concluded that the whole of an archeologist’s job is adventurous, based on just one part of the job.
7. Bricks are just atoms, so They’re Light
A brick is made up of individual, tiny atoms that weigh basically nothing. Therefore, the brick will also weigh nothing because it is made up of things that weigh basically nothing.
An argument like this is a fallacy of composition. It is taking a characteristic of the part of something – an atom – and projecting that characteristic onto the whole thing – a brick.
8. I could tear a phone book
Josh makes a bet with Clarence that he will not be able to tear a phonebook in half with his bare hands. Clarence thinks it’s an easy bet to win as a phonebook is made out of paper, and a piece of paper is so easy to tear.
Clarence tries to tear the phonebook and fails. He does not even manage to tear the first page. The cumulative strength of each page makes it impossible for him.
He committed the fallacy of composition by thinking that the characteristic of one page would apply to the whole thing – the phonebook.
9. Space is Empty
When you look up at the sky, you see mostly blackness. It doesn’t seem like there would be complex planets, stars, and solar systems out there. It seems like space is composed of nothingness.
But if you were to say that space is basically empty space, so it’s boring and not worth thinking about, you’re forgetting that there are parts of space that are incredibly interesting.
There are billions and billions of planets out in the universe. It is very possible that there are other life forms in the universe, amazing adventures to be had, and amazing things to see. Assuming there is nothing in space because it appears, on the whole, to be mostly nothing, is committing the fallacy of composition.
10. Water Pressure
Serena is learning about water pressure at school. She raises her hand and says, how can there be pressure underwater?
We all know that we float in water and she has never felt any pressure in the school pool.
Serena is committing the fallacy of composition as she is applying some ways in which water behaves in relatively small quantities, to the characteristics of water as a whole. Water, in large quantities, does exert huge pressure.
Related Fallacy: Illusory Correlation
The fallacy of composition is one in which the contents of the argument need to be closely analyzed. As we have seen in the above examples just because something is true of a part of the whole this does not mean that it is true of the whole. One coin is light but a pile of coins would be heavy.
However, there are some characteristics which are true of both the parts and the whole. A person would be correct in stating that the coin is made of metal and the whole pile of coins is also made out of metal.
Thus, in the case of this fallacy both the structure of the arguments – making assumptions about a whole thing based on its parts – and the contents need to be analyzed. Depending on the content and specific thing we are talking about, the part could either have similarities with the whole or not.
Dr. Chris Drew is the founder of the Helpful Professor. He holds a PhD in education and has published over 20 articles in scholarly journals. He is the former editor of the Journal of Learning Development in Higher Education. [Image Descriptor: Photo of Chris]