3.2 Fallacies Of Relevance

Course lecture I developed over section 3.2 of Patrick Hurley\'s "A Concise Introduction to Logic".

1. 3.23.2
Fallacies of RelevanceFallacies of Relevance

2. OverviewOverview
•Understanding fallacies of relevanceUnderstanding fallacies of relevance
•Identifying different forms of these fallaciesIdentifying different forms of these fallacies

3. What is a fallacy of relevance?What is a fallacy of relevance?
•A fallacy of relevance is one where the argument in which it occurs A fallacy of relevance is one where the argument in which it occurs
has premises that are logically has premises that are logically irrelevantirrelevant to the conclusion. to the conclusion.
•They appear to make sense though which makes them difficult to They appear to make sense though which makes them difficult to
identify.identify.
•What is flawed about an argument with a fallacy of relevance is that What is flawed about an argument with a fallacy of relevance is that
the connection between the premises and conclusion is the connection between the premises and conclusion is emotionalemotional..
–To recognize this kind of fallacy, you need to be aware of the difference To recognize this kind of fallacy, you need to be aware of the difference
between arguments that use genuine evidence and those that rely on between arguments that use genuine evidence and those that rely on
an emotional appeal.an emotional appeal.

4. Identifying fallacies of relevanceIdentifying fallacies of relevance
•Appeal to force (ad baculum)Appeal to force (ad baculum)
–Occurs whenever an arguer puts forth a conclusion and either states or Occurs whenever an arguer puts forth a conclusion and either states or
implies that if the listener does not agree then he will somehow be implies that if the listener does not agree then he will somehow be
harmed. The threat can either be physical or psychological. harmed. The threat can either be physical or psychological.
–Examples:Examples:
•““Either agree that I’m king of the world or I’ll beat you up!”Either agree that I’m king of the world or I’ll beat you up!”
•““Give me $200 or I’ll tell your wife you’re cheating on her.”Give me $200 or I’ll tell your wife you’re cheating on her.”
•Appeal to pity (ad misericordiam)Appeal to pity (ad misericordiam)
–Occurs when an arguer tries to support a conclusion by getting pity or Occurs when an arguer tries to support a conclusion by getting pity or
sympathy from the listener.sympathy from the listener.
–Examples:Examples:
•““Don’t give me a ticket, officer. My wife has cancer and my aunt just had a Don’t give me a ticket, officer. My wife has cancer and my aunt just had a
stroke!”stroke!”

5. More fallaciesMore fallacies
•Appeal to the people (ad populum)Appeal to the people (ad populum)
–The arguer manipulates the values and beliefs of people in order to The arguer manipulates the values and beliefs of people in order to
make them believe a certain conclusion.make them believe a certain conclusion.
–There are two ways of doing this:There are two ways of doing this:
•Direct approachDirect approach
–An arguer addresses a large group of people and tries to excite them and make An arguer addresses a large group of people and tries to excite them and make
them emotionally charged, so he can win their acceptance for his argument.them emotionally charged, so he can win their acceptance for his argument.
–Examples: various politiciansExamples: various politicians
•Indirect approachIndirect approach
–Arguer does not focus on the crowd itself but at certain people and how they Arguer does not focus on the crowd itself but at certain people and how they
relate to the crowd as a whole.relate to the crowd as a whole.
–Bandwagon argument – If you don’t go along with the argument, you’ll be left Bandwagon argument – If you don’t go along with the argument, you’ll be left
out. Persuaded to join in, so you can be a part of the crowd.out. Persuaded to join in, so you can be a part of the crowd.
–Appeal to vanity – Argument that compare you with someone that is admired or Appeal to vanity – Argument that compare you with someone that is admired or
pursued, and if you agree then you’ll be admired too.pursued, and if you agree then you’ll be admired too.
–Appeal to snobbery – Similar to vanity, since it implies that you’ll be a part of an Appeal to snobbery – Similar to vanity, since it implies that you’ll be a part of an
elitist crowd if you go along with the arguer.elitist crowd if you go along with the arguer.

6. More fallaciesMore fallacies
•Argument against the person (ad hominem)Argument against the person (ad hominem)
–One person makes an argument, and the other person replies with a One person makes an argument, and the other person replies with a
criticism but not one made about the argument, but about the person criticism but not one made about the argument, but about the person
himself.himself.
–Ad hominem abusiveAd hominem abusive
•Standard ad hominem argument, where the second person criticizes the Standard ad hominem argument, where the second person criticizes the
arguer instead of his argument.arguer instead of his argument.
•Example:Example:
–““John says I should quit smoking because it’s bad for me. But he’s practically an John says I should quit smoking because it’s bad for me. But he’s practically an
alcoholic, so who is he to give me advice about my health?”alcoholic, so who is he to give me advice about my health?”
–Ad hominem circumstantialAd hominem circumstantial
•Similar to ad hominem, except the second person criticizes circumstances or Similar to ad hominem, except the second person criticizes circumstances or
conditions surrounding the arguer.conditions surrounding the arguer.
•Example:Example:
–““You just want me to break up with my girlfriend so you can ask her out!”You just want me to break up with my girlfriend so you can ask her out!”

7. More fallaciesMore fallacies
–Tu quoque (you too)Tu quoque (you too)
•The second person criticizes the arguer for acting like a hypocrite or for The second person criticizes the arguer for acting like a hypocrite or for
arguing in bad faith.arguing in bad faith.
•Example:Example:
–““You’re one to yell at me about being messy. Your bedroom looks like a pigsty!”You’re one to yell at me about being messy. Your bedroom looks like a pigsty!”
•But remember, there are times when a criticism against a person can be But remember, there are times when a criticism against a person can be
properly backed up.properly backed up.
–““You lie, you cheat on your wife, and you steal cars. Therefore, you’re a bad You lie, you cheat on your wife, and you steal cars. Therefore, you’re a bad
person.”person.”
–The main point here is that the second person is bad, not that his argument is The main point here is that the second person is bad, not that his argument is
bad, and the premises here (his behavior) are supportive of the conclusion, so no bad, and the premises here (his behavior) are supportive of the conclusion, so no
fallacy is committed.fallacy is committed.

8. More fallaciesMore fallacies
•AccidentAccident
–Fallacy that is committed when a general rule is applied to a Fallacy that is committed when a general rule is applied to a
specific case it was never meant to cover.specific case it was never meant to cover.
•Example:Example:
–““Guns are responsible for many accidental deaths. Therefore, they Guns are responsible for many accidental deaths. Therefore, they
threaten the lives of police officers for carrying them.”threaten the lives of police officers for carrying them.”
–Police officers use guns as a way of maintaining peace, and this belief Police officers use guns as a way of maintaining peace, and this belief
does not cover them and their role in society.does not cover them and their role in society.
•Straw manStraw man
–An arguer distorts his opponent’s argument then defeats that An arguer distorts his opponent’s argument then defeats that
changed argument. He then concludes that he has defeated the changed argument. He then concludes that he has defeated the
original argument as well.original argument as well.
•Example:Example:
–““Many people stand in support of women’s rights. They argue it’s a Many people stand in support of women’s rights. They argue it’s a
woman’s right to choose whether to have an abortion, but abortion is woman’s right to choose whether to have an abortion, but abortion is
murder. How can these people defend murder?”murder. How can these people defend murder?”

9. More fallaciesMore fallacies
•Missing the point (ignoratio elenchi)Missing the point (ignoratio elenchi)
–In this fallacy, the premises actually support a conclusion, but a different In this fallacy, the premises actually support a conclusion, but a different
conclusion than the one presented in the argument. Usually, it’s possible to conclusion than the one presented in the argument. Usually, it’s possible to
figure out the correct conclusion since it is what actually follows from the figure out the correct conclusion since it is what actually follows from the
premises.premises.
–Example:Example:
•““American prisons are becoming overpopulated. That means we need to start American prisons are becoming overpopulated. That means we need to start
executing more people to get more space!”executing more people to get more space!”
•The logical conclusion for this argument is that we need to either build more prisons or The logical conclusion for this argument is that we need to either build more prisons or
find different ways to rehabilitate prisoners, not that we need to kill more people.find different ways to rehabilitate prisoners, not that we need to kill more people.
•Red herringRed herring
–This fallacy involves changing the subject of an argument to a slightly different This fallacy involves changing the subject of an argument to a slightly different
topic, to throw the other person off. Then a conclusion is drawn based on this topic, to throw the other person off. Then a conclusion is drawn based on this
altered argument.altered argument.
–Example:Example:
•““People say that fast food is cheap and not hard to get. But family dinners are an People say that fast food is cheap and not hard to get. But family dinners are an
important part of keeping a household together. Without quality time, most families important part of keeping a household together. Without quality time, most families
would fall apart! Parents need to shift gears and take action if they want to stay in would fall apart! Parents need to shift gears and take action if they want to stay in
touch with their kids.”touch with their kids.”