Logical Fallacies

• An improper argumentation in reasoning that leads to a
misconception or presumption.
• Often appeal to emotion or take advantage of social
• Goal is to obscure logical argument
• Asserts an argument must be true because many people believe
• If many believe it, it must be so.
“You must believe that God exists. After all, millions of people around the
world couldn’t be wrong.”
(how does this argument avoid reason?)
“Nike is the most popular shoe brand among teenagers, so it must be the
(Where is the evidence?)
• Holds an opinion to be valuable because large numbers of
people support it
• Peer pressure
• Group identity
“Polls show that Americans prefer their current health care system.”
(Are there options? Could the majority be missing something?)
“4 out of 5 people prefer Trident gum.”
(Prefer it over what? Is this the only acceptable brand?)
• Transfer of lifestyle
• Celebrities are just like us!
• Use this product, and you can be just like _______________________!
• I am just like you all – just one of the guys.
“Together, we can defeat Joe Johnson. We can make this country
great again.” – A. Politician
President Obama playing basketball; President Clinton playing the
saxophone on late-night TV
• This sort of “reasoning” appeals to one’s pity rather than one’s
sense of logic
“For just $.50 a day, you can save the life of a starving child.”
“Every day, thousands of animals die from abuse and mistreatment.”
• Threatens a series of increasingly dire consequences from
taking a simpler course of action
“First it’s gun show laws, and then they’ll come to confiscate all guns, and
then we’ll lose democracy altogether.”
(Do gun laws imply eventual confiscation?)
“Once we open up marriage to be redefined to include gay people, it will
lead to redefining it to allow polygamy, incest, and marrying pets.”
(Are these things really the same?)
• https://www.youtube.com/watch?v=Z01sQpuBe4s
• If one, then all
• If all, then one
“You’re from the south, so you must be a redneck.”
“John is a racist and he’s a Republican. All Republicans must be racist.”
• Relies on an over-exaggeration of the truth
“By using this product, you can lose up to 40 pounds in just 4 weeks!”
(They forget to mention that you also have to eat 1200 calories and work
out for 3 hours a day)
“I attended Tom Thompson’s small business seminar, and my business has
never been more successful!”
• If a person is in a position of power or has authority over
others, what they say is accepted as truth.
• Cites an authority who is not qualified to have an expert opinion
• Cites an expert when other experts agree on the issue
• Cites an expert by hearsay only
“Firemen support Jones as the best choice for city council for our town’s
(in reality, firefighters would really only be experts on fire safety)
“Dr. Smith refutes scientists’ evidence that global warming exists.”
(the vast majority of scientists agree that it does, but this expert does
• Predicts dangerous outcomes if you follow a course other than
the speaker’s
“This kind of economic policy will lose you your job and ruin your children’s
(Is there evidence that it is so? Could there be evidence to show it
might even build prosperity and create jobs?)
“Legalizing same-sex marriage would lead to the destruction of society and
to families as we know them and erode religious liberties.”
(What evidence is there of this happening? Is there any at all?)
• Attacks the person making the argument instead of the
• Attacks the person making the argument because of those with
whom he/she associates
• May insinuate the person making the argument would stand to
gain by it
“Certainly he’s in favor of a tax break for millionaires – he’s rich!”
(Could other people be benefitting, too?)
“No one who cheats on their wife could handle being President.”
(This is an attack on the person’s morals, not their stance)
“Your opinion on fashion isn’t valid; you can’t even afford new shoes!”
(This is an attack on the person’s financials, not their knowledge)
• http://politicalticker.blogs.cnn.com/2014/02/24/nugent-insistssubhuman-mongrel-comments-not-racist-promises-to-stopcalling-people-names/?hpt=hp_t2
• Committed when an irrelevant topic is presented in order to divert
attention from the original issue
• Topic A is under discussion.
• Topic B is brought up under the guise of being relevant to Topic A.
• Topic A is no longer being discussed, as all attention has turned to
Topic B.
“We must go to war and take out that country’s dictator because of all of the
terrible things he does to his people. And he has Weapons of Mass Destruction!
WMD are a threat to the entire world and must be eliminated. We must
confiscate the dictator’s WMD!”
“I deserve to have a later curfew because I’ve never broken curfew once and
I’ve always respected your rules. Besides, Jimmy has a later curfew than me and
he always breaks the rules! You obviously favor him because you let him get
away with everything. Why doesn’t he ever get punished, but I get punished
with an early curfew when I haven’t even done anything wrong?
• Offers a limited number of options – usually two – when there
are actually more choices
“Either we continue the failed war against drugs and lose another
generation or make marijuana legal.”
(are there other ways to deal with the drug issue?)
“Either you stand behind Mitt Romney, or President Obama will win again in
(What about the other Republican candidates?)
• Uses a sample too small to support the conclusion
“We’ve seen here in Smallville’s widget factory that free trade doesn’t help
the American worker.”
(How about the millions of workers elsewhere?)
“Polls in Iowa show that Rick Santorum is the clear front-runner for the GOP.”
(Is Iowa a big enough and accurate enough representation of the
American people?)
• This occurs when it is assumed that something is better or correct
simply because it is older, traditional, or has “always been
“Sure I believe in God. People have believed in God for thousands of
years, so it seems clear that God must exist.”
(Evidence? Reason?)
“Of course marriage should remain between a man and a woman. It’s been
like that for thousands of generations, so it shouldn’t change now.”
(Evidence? Reason?)
• A fallacy in which the conclusion occurs as one of the premises
• Circular logic
Bill: God must exist.
Jill: How do you know?
Bill: Because the Bible says so.
Jill: Why should I believe the bible?
Bill: Because the Bible was written by God.
(belief in God then is a foregone conclusion)
• Occurs when a perceived defect in the origin of a claim or thing
is taken to be evidence that discredits the claim or thing itself.
“The current Chancellor of Germany was in the Hitler Youth at age 3. With
that sort of background, his so-called ‘reform’ plan must be a fascist
(Because of his colored past, each decision he makes is marred by it.)
“She used to be an alcoholic, so I wouldn’t trust anything she says.”
(her past problems make discredit everything she says now?)
• Committed when a person simply ignores a person’s actual
position and substitutes a distorted, exaggerated or
misrepresented version of that position.
“I don’t believe in evolution because I don’t believe we came from monkeys.”
“Candidate B does not support forcing insurance companies to cover birth
control for women. Candidate B hates women and does not understand or
respect women’s health issues.”
(If someone disagrees with birth control, are they against women’s
health issues?)
• After this, therefore because of this
• Committed when it is concluded that one event causes another
simply because the proposed cause occurred before the
proposed effect.
“Jeff walked under a ladder, and the next day, he failed his math test. He
now knows that walking under a ladder causes bad luck.”