5 Common Logical Fallacies


Logical Fallacies

A logical fallacy is a flaw in an argument. A good understanding of logical fallacies will help you to understand whether a person is making a reasonable argument and will also help you to craft your own arguments more carefully. It may even come in handy when debating someone online on a forum or the comments section!

There are many logical fallacies. Here are five of the most common



1 Overgeneralisation

An overgeneralization is where you apply characteristics to ALL members of a group.


“All Japanese are hard-working.”
“Swedish people are all blonde.”

The Japanese have a reputation for being hardworking, but could it be that ALL Japanese are hardworking? There’s not even one lazy person in the entire nation? Are Swedish people ALL blonde? Of course not.

We can ‘fix’ these fallacies by being more careful with the language that we use:

The Japanese have a reputation for being hardworking.
Swedish people tend to be blonde.



2 Circular Reasoning

Circular reasoning is an argument that uses itself as proof. In technical terms, it uses one of its premises as its conclusion.


Bob: Professor Martin says that telepathy is possible!
Pete: Why should I believe him?
Bob: Because he’s really smart.
Pete: How do you know he’s so smart?
Bob: Because he has all these theories about telepathy!

Bob: Smoking marijuana is bad.
Pete: How do you know it’s bad?
Bob: Because it’s illegal. If it’s illegal, it must be bad.



3 False Dichotomy

The false dichotomy fallacy involves presenting an argument as if there are only two options when there are actually more.


You’d better study hard because if you don’t get a good education, you’ll never achieve anything!

From the movie, Talladega Nights:

Ricky Bobby: If you ain't first, you're last!



4 Appeal to Authority

The appeal to authority fallacy involves taking an expert’s - or so-called expert’s - opinion as fact.


Professor Martin is really smart and he says girls love guys who study science!
Carl was in the army for ten years and he says we should send in ground troops.

There are times when an expert’s opinion is worthy - especially when backed up by evidence:

Dr Cohen says that this vase is probably worth around $10,000 because the markings indicate it was made during the Ying Dynasty and it is in pristine condition.



5 Bandwagon Fallacy

As a survival mechanism, humans have a built in herd mentality. This is often taken advantage of by advertisers and politicians.

As in the idiom ‘jumping on the bandwagon’, this fallacy argues for something on the basis that it is popular or everyone believes it. Keep in mind that everyone once believed that the sun orbited the Earth.


Little Joe: Mom, can I have an iPad?
Mom: No.
Little Joe: But all the other kids have one.

Try Hapkipo Shampoo. It’s the number one shampoo in Japan!

In the second example, an ad, we could think of many reasons why Hapkipo is the number one shampoo in Japan... perhaps it’s the cheapest, but the ad is trying to have us imagine that it is number one because it is the best.




Click here to try a quiz

Click here to see an essay example