Recognizing Logical Fallacies !
A logical fallacy is a mistake in
reasoning; it is a MENTAL TRAP!

Looking at the Negative Space
• We can learn much
about logic by studying
that which is not logical—
examples of where logic
breaks down, logical
fallacies.

1. Over-generalization !
• Drawing too wide a conclusion from the
given facts !
• Example: !
– All kids cause trouble.!
– Timmy is a kid. !
– Therefore, Timmy causes trouble.!
Fix this by recognizing qualifiers
(many, few, some, all, etc.)

2. Arguing in Circles
• Def: Supporting an opinion not with evidence but with
the same opinion, slightly disguised (restating the
argument in different words). Using the word you’re
defining in the definition is a classic example.!
• Example:!
– Education is important for kids, so they should get an
education.!
– Everybody likes ice cream because it is liked by all.!
– “Belligerently” means in a belligerent way.!
Fix it by making sure you are giving support,
not just repeating the idea. Never use the
word you’re defining in the definition.!

3. Black & White Thinking
• Def. An opinion that claims there are only
two alternatives (when there might be more)
• Examples:
– You’re either for it or against it.
– Are you a jock or a nerd?
Fix this by remembering that the world is a
complicated place and that on most issues
there are many alternatives.

4. Red Herring
• Def. Presenting an irrelevant topic to divert
attention away from the original issue.
• Also known as Ad hominem: getting
personal as you discredit someone.
• Examples:
– What do you know? You’re just a kid.
– I got an F. Mr. X hates me.
Fix this by staying focused on the topic;
watch out for those who don’t.

5. Loaded Questions and
Statements
• Def. A question or a statement that
conceals an opinion or assumption.
• Examples:
– Do you still beat your dog?
– You don’t think that, do you?
– All intelligent people agree that …
Fix this by listening carefully and
separating fact from opinion.

6. Statistical Fallacies
False Authority
• Def. People usually believe in numbers and experts
without questioning them. Here statistics are used to
misrepresent rather than describe.
• Examples:
– 3 out of 4 dentists prefer Crest. (Did Crest pick the dentists?)
– I surveyed 100 people and they all agreed with me. (I chose my
friends).
– Dr. X says this is the fastest and safest way to lose weight. (Did he/
she get paid? Where do they practice?)
Fix this by analyzing the evidence. Where did the support come
from? Is there self interest involved? Did you get the whole
picture?

7. Faulty Causal Relationship
(also called Post Hoc)
• Def. To excuse an action or belief by making it sound
sensible. Often this assumes that anything that came
before an event caused it to happen.
• Example:
– I stole the towel from the hotel. They expect people to take
them.
– Eating 5 energy bars and drinking 2 Cokes helps me get better
grades. I did this and got an A on my history test.
Fix this by examining the relationship between ideas.
Make sure the facts precede the theory and the reasons
precede and cause the belief.

8. Misleading Comparison
• Def. Mistakenly believing that two
situations or people can be compared.
• Examples:
– Jill looks good in red. I’ll buy red pants, too.
– Forcing students to read books is like herding
cattle to slaughter.
– You gave him extra time on the test, so I should
get extra time too.
– Saddam Hussien is Hitler.
Fix this by remembering that every person
and situation has different circumstances.

9. Bandwagon
• Def. Lots of people do this, so you should,
too.
• Examples:
– Adults are smoking, so it is ok to do so.
– The American people do not stand for . . .
Fix this by making decisions based on facts,
not popularity.