This document provides definitions and examples of logical fallacies and reasoning terms that may be covered on an IB TOK logical fallacy test. It defines deductive and inductive reasoning, syllogisms, truth vs. validity, and Venn diagram construction. It then defines and provides examples of several common logical fallacies, including ad hominem, ad ignorantiam, appeal to emotion, appeal to fear, bandwagon, begging the question, and false analogy. The document aims to help students review and understand key logical reasoning concepts and identify logical fallacies.

1. IB TOK Logical Fallacy Test Review by Pure Due: 11.18.2011
TERMS/CONCEPTS DEFINITIONS EXAMPLES
Deductive Reasoning Reasoning from the general to the ∙ All men are mortal
particular (or from cause to ∙ Socrates is a man
effect). ∙ Therefore, Socrates is mortal.
Inductive Reasoning Reasoning from detailed facts to ∙ The base costs are $6.00.
general principles. ∙ The extras are $0.24.
∙ Overall, it is great deal at $6.24.
Syllogisms Deductive reasoning in which a ∙ All humans are mortal (the
conclusion is derived from two major premise).
premises. ∙ I am a human (the minor
premise).
∙ Therefore, I am mortal.
Truth vs. Validity ∙ Truth - a statement proven to ∙ Truth: Pure is a girl. Pure is
be or accepted as true. Chinese. Therefore Pure is a
∙ Validity - the conclusion Chinese girl.
follows conclusively from the ∙ Validity: Pure is a girl. Pure is an
premises. alien. Therefore Pure is a girl
alien.
Venn Diagram Construction A diagram using circles to
represent sets, with the position
and overlap of the circles
indicating the relationships
between the sets.
Enthymemes A syllogism in which one of the ∙ She is Chinese.
premises or the conclusion is not ∙ She is good at math.
stated explicitly - omitted. ∙ Missing: Chinese are good at
math.
LOGICAL FALLACIES DEFINITIONS EXAMPLES
Ad Hominem Make an irrelevant attack on the What she says about Johannes
arguer and suggest that this attack Kepler’s astronomy of the 1600′ s
undermines the argument itself. It must be just so much garbage. Do
is a form of the Genetic Fallacy. you realize she’s only fourteen years
old?
Ad Ignorantiam “Appeal to Ignorance” Nobody has ever proved to me
∙ Not knowing that a certain there’s a God, so I know there is no
statement is true is taken to God.
be a proof that it is false.
∙ Not knowing that a statement
is false is taken to be a proof
that it is true.

2. IB TOK Logical Fallacy Test Review by Pure Due: 11.18.2011
Appeal to Emotion When someone’s appeal to you to The new UltraSkinny diet will make
accept their claim is accepted you feel great. Enjoy the admiring
merely because the appeal stares of the opposite gender. You
arouses your feelings of fear, love, will know true happiness if you try
outrage, pride, sympathy, relief, our diet!
and so forth.
Appeal to Fear “Argumentum Ad Metum” "You know, Professor Smith, I really
“Argumentum in Terrorem” need to get an A in this class. I'd like
A person attempts to create to stop by during your office hours
support for his or her idea by later to discuss my grade. I'll be in
using deception and propaganda your building anyways, visiting my
in attempts to increase fear and father. He's your dean, by the way.
prejudice toward a competitor. I'll see you later."
Bandwagon Suggest that someone’s claim is Everyone’s coming to the Talent
correct simply because it’s what Show, so you should too!
most believe. Afterwards, we’re going to HuNan
Restaurant in Fairfax, and then we’re
going over to someone’s house to
catch a movie. Come with us!
Begging the Question A form of circular reasoning in “Women have rights,” said the
which a conclusion is derived from Bullfighters Association president.
premises that presuppose the “But women shouldn’t fight bulls
conclusion. No progress is made. because a bullfighter is and should
be a man.”
Circular Reasoning When the reasoner begins with ∙ Definition: endless loop, n. See
what he or she is trying to end up loop, endless.
with. ∙ Definition: loop, endless, n. See
endless loop.
Continuum Fallacy “Line Drawing” Dwayne can never grow bald.
Improperly reject a vague claim Dwayne isn’t bald now. Don’t you
because it’s not as precise as we’d agree that if he loses one hair, that
like. won’t make him go from not bald to
bald? And if he loses one hair after
that, then this one loss, too, won’t
make him go from not bald to bald.
Therefore, no matter how much hair
he loses, he can’t become bald.
Equivocation Illegitimate switching of the Brad is a nobody, but since nobody
meaning of a term during the is perfect, Brad must be perfect, too.
reasoning.

3. IB TOK Logical Fallacy Test Review by Pure Due: 11.18.2011
False Analogy “Faulty Comparison” The book Investing for Dummies
When the analogy is irrelevant or really helped me understand my
very weak or when there is a more finances better. The book Chess for
relevant disanalogy. Dummies was written by the same
author was published by the same
press, and costs about the same
amount. So, this chess book would
probably help me understand my
finances, too.
False Dilemma A reasoner who unfairly presents Anonymous: So my girlfriend and I
too few choices and then implies had a fight, I know you guys are
that a choice must be made really good friends, but you have to
among this short menu of choices. choose between the two of us in
order to keep our friendship. [when
in reality] The listener can be friend
the two of them, or neither.
False/Anonymous The authority appealed to is not The moon is covered with dust
Authority really an authority in this because the president of our
particular subject, when the neighborhood association said so.
authority cannot be trusted to tell
the truth, when authorities
disagree on this subject.
Hasty Generalization “Biased Statistics” I’ve met two people in Nicaragua so
Jumping to conclusions in which far, and they were both nice to me.
the conclusion is a generalization. So, all people I will meet in
Nicaragua will be nice to me.
Jargon Specialized language concerned Wats up dog! <---- What’s up man?
with a particular subject, culture,
or profession. Such as sign
language and slang.
Kettle Logic One uses multiple arguments to ∙ That he had returned the kettle
defend a point, but the arguments undamaged.
themselves are inconsistent. ∙ That it was already damaged
when he borrowed it.
∙ That he had never borrowed it in
the first place.
Loaded Questions The rhetorical trick of asking a Have you stopped cheating on
question that cannot be answered homework and projects?
without admitting a
presupposition that may be false.

4. IB TOK Logical Fallacy Test Review by Pure Due: 11.18.2011
Moving the Goalposts “Raising the Bar” In order to receive an A on this
Evidence presented in response to assignment you need to give 100
a specific claim is dismissed and examples. [after the due date] Wait,
some other (often greater) I’ve changed my mind, let’s go with
evidence is demanded. 200 instead. [everyone got a 50%]
Non-Sequitor “It Does Not Follow” We should maintain a clean
A conclusion that does not follow environment. The atmosphere is
from the premises. polluted…we need to recycle! Oh,
gas is so expensive!
Oversimplification Cover up relevant complexities or President Bush wants our country to
make a complicated problem trade with Fidel Castro’s Communist
appear to be too much simpler Cuba. I say there should be a trade
than it really is. embargo against Cuba. The issue in
our election is Cuban trade, and if
you are against it, then you should
vote for me for president.
Post Hoc Ergo Propter Hoc “After This, Therefore Because of More and more young people are
This” attending high schools and colleges
∙ Believing that temporal today than ever before. Yet there is
succession implies a causal more juvenile delinquency and more
relation. alienation among the young. This
∙ A occurred, then B occurred. makes it clear that these young
∙ Therefore, A caused B. people are being corrupted by their
education.
Slippery Slope The likelihood of the trouble ∙ Mom: Those look like bags
occurring is exaggerated. under your eyes. Are you getting
∙ A leads to B. enough sleep?
∙ B leads to C. ∙ Jeff: I had a test and stayed up
∙ C leads to D. late studying.
∙ … ∙ Mom: You didn’t take any drugs,
∙ Z leads to… did you?
∙ Jeff: Just caffeine in my coffee,
like I always do.
∙ Mom: Jeff! You know what
happens when people take
drugs! Pretty soon the caffeine
won’t be strong enough. Then
you will take something
stronger, maybe someone’s diet
pill. Eventually, you will be doing
cocaine. Then you will be a drug
addict! So, don’t drink that
coffee.

5. IB TOK Logical Fallacy Test Review by Pure Due: 11.18.2011
Special Pleading Applying a general principle to Everyone has a duty to help the
various situations but not applying police do their job, no matter who
it to a special situation that the suspect is. That is why we must
interests the arguer even though support investigations into
the general principle properly corruption in the police department.
applies to that special situation, No person is above the law. Of
too. course, if the police come knocking
on my door to ask about my
neighbors and the robberies in our
building, I know nothing. I’m not
about to rat on anybody.
Straw Man Attribute an easily refuted ∙ Opponent: Because of the killing
position to your opponent, one and suffering of Indians that
that the opponent wouldn’t followed Columbus’s discovery
endorse, and then proceed to of America, the City of Berkeley
attack the easily refuted position should declare that Columbus
(the straw man) believing you Day will no longer be observed
have undermined the opponent’s in our city.
actual position. ∙ Speaker: This is ridiculous, fellow
members of the city council. It’s
not true that everybody who
ever came to America from
another country somehow
oppressed the Indians. I say we
should continue to observe
Columbus Day, and vote down
this resolution that will make the
City of Berkeley the laughing
stock of the nation.