TUTORIAL - Informal Logical Fallacies

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Pyrrho
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TUTORIAL - Informal Logical Fallacies

Post by Pyrrho »

These definitions are unfortunately brief. More detailed definitions can be obtained online at various locations. I suggest performing a Google search for "logical fallacies" for further quick reference. My primary reference has been "Fundamentals of Logic - Second Edition", by James D. Carney and Richard K. Scheer, (C) 1974 Macmillan Publishing Company, Inc., ISBN 0-02-319430-8

Basic Logical Terms
argument - a set of statements given as reasons for another statement
premise - a given statement; part of the argument
conclusion - the statement for which reasons (arguments and premises) are given

Informal Logical Fallacies
ad hominem or “To the Man” - the reasons given for a conclusion are no more than a criticism of a person or their particular circumstances. It also takes the form of assigning labels to people. Example: “Mr. Smith uses foul language; therefore he is immoral and anything he says is nonsense." Another example: "The French-looking John Kerry."(1)

tu quoque or "You're Another" - an argument is answered by responding with the same or similar arguments which are irrelevant to the conclusion. Example: “Yes, I use foul language, but so do you.”

Appeal to Popularity - the argument is held to be true just because it is widely believed to be true. Example: “More than 70% of all people have had paranormal experiences, therefore the paranormal is real,” or “Everybody knows we only use 10% of our brains.”

"Appeal to Pity" or "Appeal to Emotion" - a form of Appeal to Popularity which attempts to invoke sympathy in order to support a conclusion. Example: “If we don’t end farm subsidies, millions of children will starve to death.”

"Appeal to Force" or "Appeal to Consequences" - the argument takes the form of "might makes right" or warns that if the conclusion is not accepted then dire consequences will result. Example: “Get right with God, or you’ll be swept into Hell,” or “Those who don’t believe in the paranormal must be sad people.”

"Appeal to Authority" - committed when one attempts to support a conclusion by citing a person or persons who already assert the same conclusion, but who are not qualified to assert that conclusion. Often occurs when a person claims to be an authority when they are not. Note: if the authority cited is a reliable, qualified authority concerning the conclusion, this can be a valid argument. The fallacy lies in citing an authority that is not reliably qualified to assert the conclusion. Example: “Joe the plumber says that ghosts are electromagnetic plasma produced by the spirit.”

"Appeal to Ignorance" – committed when the conclusion is asserted as true because there is no proof that it is false, or false when there is no proof that it is true, as in "there is no proof that p is false, therefore p is true" and vice-versa. There are two exceptions to this fallacy. One in certain courts of law, where people are presumed to be innocent until judged guilty. Another occurs in science, when a conclusion can be considered to be false when evidence cannot be found to support the conclusion, assuming that the scientist is expert enough to find evidence if it existed. Example: “We don’t know how certain processes in evolution work, therefore there must be an intelligence guiding the process.” Or “It cannot be proven that ghosts do not exist, therefore we should assume that they exist.”

"Begging the Question", "Circular Reasoning" - an argument is used to support itself, as in p is true, therefore p is true, or p is true because q is true, q is true because r is true, and r is true because p is true. The conclusion repeats the reason or premise. Example: “The Bible is can’t be wrong because it is the word of God. God can’t be wrong because the Bible says He cant’, and we know the Bible can’t be wrong because it is the word of God.”

Complex Question - the arguments presuppose that the conclusion is true. Also known as a "Catch-22" or "double bind" or "forcing the conclusion". Example: “When did you stop beating your wife?”

Genetic Fallacy - often a variation of ad hominem, the arguer describes the process that they feel led someone to a conclusion and infers from that process that the conclusion is false. Example: “You made an error in your reasoning at Steps 10 and 23, therefore your conclusion is false.” Not necessarily so.

Straw Man - committed when a conclusion is misinterpreted or misrepresented an attempt is made to refute the misinterpreted or misrepresented conclusion. Example: “In your analysis of fried eggs, you said that brown eggs taste better than white eggs. Obviously you believe that white chickens are inferior to brown chickens. Well, genetic studies of all kinds of chickens show that brown chickens and white chickens are equally good.”

"False Cause" or "False Analogy" - argument in which one gives an incorrect or unrelated reason for a given conclusion. Example: “When people tell me that apples are red, I can verify that they are red. This means that people are reliable, so when they tell me that ghosts are real I can assume that ghosts are as real as apples are red.”

Special Pleading - the arguer considers only those reasons that support the conclusion. To avoid this fallacy the arguer must consider reasons both pro and con. Example: “It doesn’t matter that magicians can do what psychics can do. Psychics have genuine powers.”

Hasty Generalization - the arguer infers from an insufficiently large or quantitatively unrepresentative sample (fallacy of small sample) or when one infers from a peculiarly selected or qualitatively unrepresentative sample (fallacy of biased statistics). Example: “Our survey of fifteen dentists show that nine out of ten dentists agree!”

Equivocation - words or expressions having multiple meanings are used inconsistently and the correctness of the argument depends on consistent definition. Example: “I am a true skeptic. You are a false skeptic.”

Fallacy of Division - committed when someone argues that something which is true only of the whole is also true of its parts taken separately. Example: “Chemical A and Chemical B explode when mixed together. Therefore each chemical must contain an explosive quality.”

Fallacy of Composition - committed when someone argues that what is true only of the parts is also true of the whole. Example: “Bird can fly because they have wings. Therefore a bird’s wing should be able to fly by itself.”

Fallacy of Accent - committed when a statement is accented in a way that changes its meaning, and is used in an argument.

False Dilemma - arguer asserts that there are only two possibilities for a conclusion, when there are more. Example: “Either we drag icebergs to San Francisco for water, or California will go completely dry.”

(1) A true-to-life example; this statement has been frequently uttered by Rush Limbaugh when arguing against statements made by Mr. Kerry.

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Post by Sundog »

I've always wondered why "appeal to pity" is listed as a logical fallacy. It would be, of course, were someone to actually use it to try to justify the logic of a position. By far the more common usage, it seems to me, is an appeal to "put aside" the train of logic for a moment and balance it against certain consequences.

Used this way it isn't a logical fallacy at all, and it isn't reasonable to dismiss it on this pretext. For example:

Bob lays out a very logical argument for Bush's rewriting of the regulations pertaining to overtime.

Alice says, "But millions of people rely on this extra money to get by!"

Bob rejects Alice's statement, citing appeal to pity. He's wrong; Alice isn't attempting to refute Bob's logic, she's simply saying that logic is not the only thing to be taken into account when making decisions like this.

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Post by Grammatron »

Pyrrho, thank you very much for posting that, I always wondered what the accurate definition of some of these was.

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Re: TUTORIAL - Informal Logical Fallacies

Post by gnome »

Pyrrho wrote:Fallacy of Composition - committed when someone argues that what is true only of the parts is also true of the whole. Example: “Bird can fly because they have wings. Therefore a bird’s wing should be able to fly by itself.”
I think this example is flawed... this is just another Fallacy of Division. May I suggest: "Everything that goes into making a computer is incapable of independent thought. Therefore a computer is incapable of independent thought."

Note: this may not be the best example after all. The argument is fallacious, but the conclusion could be true. It's easier to understand the fallacy with an obviously false conclusion. Anyone else have ideas?

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Post by rwald »

The prescribed Google search takes you to the following two pages:

http://www.datanation.com/fallacies/index.htm

http://www.nizkor.org/features/fallacies/

Both of these are good, including examples, discussion, etc.


Edit: Gnome, an example might be, "Every atom in this cell is not alive, so the cell is not alive."
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Re: TUTORIAL - Informal Logical Fallacies

Post by viscousmemories »

gnome wrote:
Pyrrho wrote:Fallacy of Composition - committed when someone argues that what is true only of the parts is also true of the whole. Example: “Bird can fly because they have wings. Therefore a bird’s wing should be able to fly by itself.”
I think this example is flawed... this is just another Fallacy of Division. May I suggest: "Everything that goes into making a computer is incapable of independent thought. Therefore a computer is incapable of independent thought."

Note: this may not be the best example after all. The argument is fallacious, but the conclusion could be true. It's easier to understand the fallacy with an obviously false conclusion. Anyone else have ideas?
To stick with the bird analogy, how about: "Wings enable flight, therefore penguins can fly."

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Post by viscousmemories »

Sundog wrote:I've always wondered why "appeal to pity" is listed as a logical fallacy. It would be, of course, were someone to actually use it to try to justify the logic of a position. By far the more common usage, it seems to me, is an appeal to "put aside" the train of logic for a moment and balance it against certain consequences.

Used this way it isn't a logical fallacy at all, and it isn't reasonable to dismiss it on this pretext. For example:

Bob lays out a very logical argument for Bush's rewriting of the regulations pertaining to overtime.

Alice says, "But millions of people rely on this extra money to get by!"

Bob rejects Alice's statement, citing appeal to pity. He's wrong; Alice isn't attempting to refute Bob's logic, she's simply saying that logic is not the only thing to be taken into account when making decisions like this.
Hmm... I think your analogy is incomplete. It's not obvious what Bob and Alice's arguments or conclusions are, so it's impossible to say whether her comment is fallacious.

For example, if Bob said "We can save 10 million dollars by rewriting the overtime regulations", it would be a fallacious appeal to pity for Alice to respond, "No we can't. Millions of people are relying on this money."

However, if Bob said "We should rewrite the overtime regulations because we can save 10 million dollars", it would not be a fallacious appeal to pity for Alice to say, "No we shouldn't. Millions of people are relying on this money".

In the first case the argument is that 10 million dollars can be saved by a certain action, and the fact that people are relying on that money doesn't change that fact. In the second case the argument is that the action should be taken on the grounds that 10 million dollars can be saved, so it is fair for Alice to point out that how much money can be saved isn't the only factor.

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Post by viscousmemories »

rwald wrote:The prescribed Google search takes you to the following two pages:

http://www.datanation.com/fallacies/index.htm

http://www.nizkor.org/features/fallacies/

Both of these are good, including examples, discussion, etc.
My introduction to the topic came from the Infidels site:

http://www.infidels.org/news/atheism/logic.html

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Post by Chaos »

"Appeal to Authority" - committed when one attempts to support a conclusion by citing a person or persons who already assert the same conclusion, but who are not qualified to assert that conclusion. Often occurs when a person claims to be an authority when they are not. Note: if the authority cited is a reliable, qualified authority concerning the conclusion, this can be a valid argument. The fallacy lies in citing an authority that is not reliably qualified to assert the conclusion. Example: “Joe the plumber says that ghosts are electromagnetic plasma produced by the spirit.”
I have a problem with that fallacy. How exactly is it decided who is
a reliable, qualified authority concerning the conclusion?

For example - and I´m talking strictly as advocatus diaboli here -, are creationist biologists (and I guess there are some) still reliable, qualified authorities on the creation vs. evolution controversy? If so, why are you still so sure they are wrong? Why do you not accept what they say? If they are not authorities, what makes them different from evolutionist authorities? Why do you believe these, but not creationists?

Appeal to authority is a fallacy, all right, but that exception you make does not hold up to close scrutiny.
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Re: TUTORIAL - Informal Logical Fallacies

Post by Rattus »

Pyrrho wrote:
ad hominem or “To the Man” - the reasons given for a conclusion are no more than a criticism of a person or their particular circumstances. It also takes the form of assigning labels to people. Example: “Mr. Smith uses foul language; therefore he is immoral and anything he says is nonsense." Another example: "The French-looking John Kerry."(1)
I think it's important to remember that ad hominems are fallacies even if they are true. For instance the fact that Bush is a retard doesn't make the war in Iraq any more or less justified.
Pyrrho wrote: Appeal to Popularity - the argument is held to be true just because it is widely believed to be true. Example: “More than 70% of all people have had paranormal experiences, therefore the paranormal is real,” or “Everybody knows we only use 10% of our brains.”
This fallacy works in reverse, i.e. the unwashed masses believe in it so it must be false.
Pyrrho wrote: "Appeal to Pity" or "Appeal to Emotion" - a form of Appeal to Popularity which attempts to invoke sympathy in order to support a conclusion. Example: “If we don’t end farm subsidies, millions of children will starve to death.”
In the example it would only be a fallacy to bring up the death of the children to support the argument. Bringing up the consequence of one's conclusion cannot be a fallacy however, if it really is true that millions of children will die unless we end farm subsidies, that is a pretty compelling argument to end farm subsidies.
Also works in reverse, for example I've seen a negative portrayal of the Crusades dismissed as an attempt to invoke "White Man's Guilt", i.e. he didn't like how the conclusion made him feel, so he rejected it.

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Post by whitefork »

The nonconforming fallacy:

The premises of this argument are true
The conclusion of this argument is true
Therefore the argument is valid.
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Post by Doctor X »

What?

No Latin?

Bah!

--J. "Argumentum Non Verus Caledoni" D.
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Post by gnome »

Doctor X wrote:What?

No Latin?

Bah!

--J. "Argumentum Non Verus Caledoni" D.
Argumentum Ad Latinum

The fallacy of using Latin to increase the credibility of an argument--in the hope that those that do not know Latin won't reveal their ignorance by questioning it.

:D

(BTW for those actually trying to learn these, this isn't a real one. I made it up)

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Post by Doctor X »

Those who know Latin knew that. . . .

--J.D.
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"I'd leave it up to Doctor X who has been a benevolent tyrant so far." – Grammatron
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Shit. That's going to end up in your sig." – Pyrrho
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Post by gnome »

Doctor X wrote:Those who know Latin knew that. . . .

--J.D.
Could "those who know Latin" be so kind as to correct mine? Maybe this could become a more legitimate fallacy...

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Post by Doctor X »

Sorry, if you are not an initiate in the Mysteries. . . .

More seriously, the tactic is not so much a fallacious argument but a "dazzle them with bullshit." To use "big words" appropriately is merely excellent vocabulary or poor craftsmanship--depending on the author and audience. As I have reminded many, I cannot call somone on a fallacy if they do not use the fallacy.

For example, if you make a potentially legitimate argument, I can throw a Latin name at it, but if it is not relevant, it is not relevant:

gnome: I am concerned that his willingness to lie under these circumstances suggests a lack of ethics that may indicate he will lie in the future.

Moi: Argumentum ad veritatem obfuscandam dip shit.

In that case, it is an incorrect fallacy and a non sequitur.

Have to run. . . .

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"Doctor X is just treating you the way he treats everyone--as subhuman crap too dumb to breathe in after you breathe out." – Don
DocX: FTW. – sparks
"Doctor X wins again." – Pyrrho
"Never sorry to make a racist Fucktard cry." – His Humble MagNIfIcence
"It was the criticisms of Doc X, actually, that let me see more clearly how far the hypocrisy had gone." – clarsct
"I'd leave it up to Doctor X who has been a benevolent tyrant so far." – Grammatron
"Indeed you are a river to your people.
Shit. That's going to end up in your sig." – Pyrrho
"Try a twelve step program and accept Doctor X as your High Power." – asthmatic camel
"just like Doc X said." – gnome

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Post by Chaos »

gnome wrote:
Doctor X wrote:What?

No Latin?

Bah!

--J. "Argumentum Non Verus Caledoni" D.
Argumentum Ad Latinum

The fallacy of using Latin to increase the credibility of an argument--in the hope that those that do not know Latin won't reveal their ignorance by questioning it.

:D

(BTW for those actually trying to learn these, this isn't a real one. I made it up)
It should be a fallacy... "appeal to ignorance of big words" or something like that.
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Post by exarch »

Chaos wrote:It should be a fallacy... "appeal to ignorance of big words" or something like that.
I think there already is a term for that. The fallacy of making the argument needlessly complex.
Confounding your opponent by incorporating multi-syllable terms that are completely superfluous so to speak :D
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Post by xouper »

exarch wrote:
Chaos wrote:It should be a fallacy... "appeal to ignorance of big words" or something like that.
I think there already is a term for that. The fallacy of making the argument needlessly complex. Confounding your opponent by incorporating multi-syllable terms that are completely superfluous so to speak :D
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Re: TUTORIAL - Informal Logical Fallacies

Post by Abdul Alhazred »

Pyrrho wrote: tu quoque or "You're Another" - an argument is answered by responding with the same or similar arguments which are irrelevant to the conclusion. Example: “Yes, I use foul language, but so do you.”
There is a variant to this common in politics. I call it "pre-emptive you're another". This consists of falsely accusing your opponent of the malfeasance you yourself are doing. That way, when your opponent accuses you, it looks like a lame "you're another".
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