A relevance fallacy is a type of informal fallacy that relies on irrelevant emotional appeal, instead of logical argument, to reach conclusions. Arguments that commit such fallacies play to our emotions, such as fear, guilt, pity, loyalty, and biases, instead of drawing conclusions rationally.
Ignoratio Elenchi (Red Herring) is the only relevance fallacy considered by Aristotle. Most of the rest of the fallacies below are relatively recently named (even the ones with Latin names), mostly in the nineteenth and twentieth centuries.
Here is a sample of relevance fallacies:
- Ignoratio Elenchi (Red Herring)
- To commit this fallacy is to introduce irrelevant material to the issue
being discussed, so that everyone's attention is diverted away from the
points being made, towards a different conclusion. All relevance fallacies are types of this fallacy.
- Argumentum ad Verecundiam (Appeal to Authority)
- Appeal to Authority uses the opinion of an
authority or famous person to support an assertion. This line of
argument is not always incorrect; for most things in our lives, we
have to rely on the word of an authority; we quite simply don't have the time or other resources to investigate and argue everything from first principles. The fallacy lies in using
an authority in place of arguing based on the subject matter, or
taking as authoritative a statement that might not be authoritative.
Some examples:
- Joe said that 2 + 2 = 4, and he has an
advanced degree in mathematics. Therefore, 2 + 2 = 4.
- The Earth is flat, since many philosophers in the Middle Ages
believed that it was flat.
- Mr. X said that September has 31 days [when he was having a bad day, perhaps].
Therefore September has 31 days.
- Argumentum ad Populum (Appeal to Popularity)
- Appeal to Popularity is a fallacy that asserts
that an assertion is correct based on its support by a large group of
people. For example: "The movie Harry Potter And The Philosopher's
Stone grossed a record amount of money in its first week.
Therefore, it is a very high-quality movie".
- Argumentum ad Baculum (Appeal to Force)
- This fallacy is committed when the arguer
resorts to force the acceptance of a conclusion by threating someone
with harm, either directly or indirectly. For example:
- If you don't believe that Margaret Thatcher was the greatest
British Prime Minister of the 20th century, I'll give
you a failing grade in the course.
- You should stop eating hamburgers, or else you'll get Mad Cow Disease.
- Argumentum ad Misericordiam (Appeal to Pity)
- Appeal to Pity is in a way the opposite of
the Appeal to Force. It suggests that harm will come to the arguer
unless a certain conclusion is accepted.
- Fallacy of Collective Inference
- This fallacy is related to appeal to authority. It occurs when several different authorities are used to support premises in an argument, but where no one authority would agree with all of the premises or the conclusion.
- Argumentum ad Ignorantiam (Argument from Ignorance)
- This fallacy occurs whenever someone argues that something must
be true because it has not been proven false, or false because it
has not been proven true. For example, "Psychic phenomena don't
exist, since no-one has proved that they are real," or "Psychic phenomena
exist, since no-one has proven them to be false."
- Argumentum ad Antiquam
- This is the fallacy of arguing in favour of something simply because
it is old. For example, "That's the way we've always done it."
- Argumentum ad Novitam
- The opposite of Argumentum ad Antiquam, this fallacy is the fallacy of
arguing in favour of something simply because it is new or newer than
something else.
- Argumentum ad Crumenam
- This fallacy occurs when it is argued that someone is correct because
that person has more money.
- Argumentum ad Lazarum
- This fallacy occurs when it is argued that someone is correct because
they are poor. This fallacy is the opposite of Argumentum ad Crumenam.
- Argumentum ad Nauseam
- This fallacy involves arguing that an assertion is true because it
is heard frequently.
- Argumentum ad Personam (Appeal to Personal Interest).
- This fallacy involves appealing to another person's preferences, biases,
predispositions, and the like in order to have them accept the argument.
- Ad Hominem
- Literally, an argument directed "at the man". There are two forms
of ad hominem: the abusive variety occurs when
an arguer attacks those making an assertion (which isn't really an argument at all), and the circumstantial
variety occurs when one argues that one's opponent ought to accept the
truth of an assertion because of the opponent's particular circumstances.
- Straw Man
- The straw man fallacy is to misrepresent a position so that it is
easier to "knock down", proceed to do so, and then claim that the
original position has been destroyed.
- Tu Quoque
- Tu Quoque is Latin for "you too". This fallacy occurs when an
action is said to be acceptable because the opposing party has done it.
For example:
Person 1: | You were driving way too fast there!
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Person 2: | So? You drive too quickly too.
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