Adam vanLangenbergMSSS

Logical Fallacies 101

Ad ignorantiam

“We don’t know what those lights in the sky are, therefore they are aliens.”

Claiming that something is true because we can’t

disprove it.

Argument from

authority

“I use these magical healing crystals every day!” – Dr S. Novella, M.D.

The idea that something must be true because it has been said by

somebody with authority.

Argument from Final

Consequences

“Aliens must exist because otherwise we would be all alone in the universe.”

Making an argument based on how good/bad the consequences are.

Argument from Personal Incredulity

“I don’t understand how evolution works so there must be an intelligent designer.”

Claiming that something is impossible because you

personally don’t understand it.

Argument from Antiquity

“Of course it’s legitimate! Cave men have been doing this for millions of years!”

Stating that something must be good because it has been

used for a long time.

Argument from Popularity

“1 million Usher fans can’t be wrong!”

Stating that something must be legitimate because a lot of people believe in it.

Correlation vs.

Causation

“I have never been attacked by a bear while wearing this tie. Bear-proof tie!”

Assuming cause and effect for two things simply because

they occurred together.

Unexplained vs.

Unexplainable

“We don’t know what the Voynich Manuscript means so it must have been

written by angels!”

Believing that because we cannot explain some phenomenon now,

we will never be able to explain it.

False Continuum

“There’s a fuzzy line between religions and cults, so all religions must be cults.”

Thinking that because no distinct line exists between two extremes, then those two extremes are really

the same thing.

False Dichotomy

“Either you are with us, or you are with the terrorists.”

Insisting that things must either be one way or

another.

Inconsistency

“Prescription drugs need to be strongly regulated but herbal supplements do not.”

Applying criteria to one thing but not to another.

Non-Sequitur

“God is love. Love is blind. Ray Charles is blind. Therefore Ray Charles is God.

Making a conclusion that doesn’t follow from the

arguments.

Post-hoc ergo propter hoc

“A rooster crows before the sun rises so the rooster’s crowing must cause the sun to

rise. Clever rooster!”

Saying that because A happened before B, A must have caused B.

Reductio ad absurdim

“If you don’t believe in aliens because you haven’t seen one, how can you believe in

France? You haven’t seen it either.”

Extending an argument to an absurd conclusion.

Ad hominem

“Your argument is wrong because you’re a big fatty fat fat.”

(My favourite)

Attacking a person, rather than their claims.

Slippery slope

“If you support the death penalty then you must also support genocide.”

Arguing that believing something must also involve

believing in its extreme.

Special pleading

“My psychic powers didn’t work because of all the sceptics in the room! Also, because

of magnetic interference.”

Arbitrarily introducing something into an

argument to make it work.

Straw man

“I think homeopathy is stupid and should be banned.”

“So you think we should ban medicines, do you?”

Twisting your opponent’s argument to make it

easier to argue against.

Tautology

“Go to bed.”“Why?”

“Because I said so.”

The argument that A = B because A = B.

Moving the

goalpost

“…and that is why your mother is fat.”“Oh yeah? Well then what is she eating

right now?”

After losing an argument, throwing something else into the ring which cannot yet be

proven.

Tu quoque

“You can’t say murder is wrong, you’re a serial killer!”

Attacking somebody for arguing against something

that they used to do.

Begging the question

“It is McDonald’s fault that I am fat!”

Not stating something important that your argument assumes.