10 common fallacies

Posted on 6 June 2011 by


Ten common fallacies you should all know

Fallacies: Incorrect or misleading beliefs or opinions based on inaccurate facts or invalid reasoning.

Ad Hominem

When someone attacks the person instead of the argument.

“Jenny’s just a stupid blonde on  the dole.  Why would you ever consider her strategy for getting a job.”
“Mike cheated on his final exam. You can’t trust him to know the answers to any of your questions.”

Appeal to authority

When a statement is considered true because it’s made by someone who is considered an “authority” on the topic.

Source A says that “Q” is true.
Source A is authoritative.
Therefore, “Q” is true.

“My doctor says taking St John’s Wort everyday will make me less depressed. He should know, he’s a doctor!”
“The policeman said it’s legal for him to search my car. He’s a policeman, so he must be telling the truth.”

Appeal to Ignorance

When a claim is considered true because it hasn’t been disproven (or vice versa).

“Since you cannot prove that Aliens do not exist, then they must exist.”
“John said he saw a UFO last night, but he didn’t get a photo. He must be lying.”

Bandwagon Fallacy
When a concept is considered true because lots of people believe it’s true.

“9 out of 10 doctors agree that Medicine X is the best. So then Medicine X must be the best.”
“This TV show is the best show on TV right now. Everyone is watching it!”

Begging the Question

When the statement is assumed true based on the statement itself.

“The Bible is the word of God, because it says so in the Bible.”
“How do I know he’s stupid? Because he doesn’t know anything about anything.”
“Marijuana wouldn’t be illegal if it wasn’t seriously harmful to your health.”

Loaded Question
When a question contains the presumption of guilt.

“So when exactly did you stop hitting your wife?” (Assumes the person WAS hitting his wife).
“Being that smacking children is a good parenting technique, should it be allowed in Ireland ”

Non Sequitor

When a statement’s conclusion does not follow from its premise.

“If you don’t buy this magic fish oil pill, then you are neglecting your children’s health.”
“I hear loud shouting and rustling noises through the wall. The man next door must be hitting his wife.”

Red Herring
When someone diverts the attention away from the topic to a NEW topic to throw you off and win the argument.

Topic A is being debated.
Topic B is introduced as being related to Topic A.
Topic A is abandoned.
Now Topic B is being used to discredit you.


“So you dont agree with bloodsports, well you say that case where a fox came and ate the faces off children in their own livingroom, you want that? You want to see children maimed by foxes? Go ahead and protest against bloodsport”.

Slippery Slope

When it’s assumed that a small step leads to a larger chain reaction of events resulting in a greater impact.

“Once the government has passed this gun law, they’ll pass other gun laws resulting in total confiscation.”
“If we legalize marijuana , then next thing you know we’ll be handing needles out to ten year olds.”

Straw Man

When someone ignores the argument and replaces it with a distorted or exaggerated version of that argument.

Person A: “Evolution states that humans developed over a long time from the same common ancestor as the gorilla.”
Person B: “Everyone listen to Person A. He’s saying that we descended from baboons!!!”