Informal fallacy

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An '''informal fallacy''' (also '''presumption fallacy''', '''soundness fallacy''') is an argument that is [[Logical validity|formally valid]] but is [[Soundness|unsound]] because of the lack of truth of one or more of its premises. Informal fallacies are characterised by the fact that although there is a connection between their ''premises'' and their ''conclusion'' — i.e. they have a valid form — their premises are unsupported. All informal fallacies are forms of question-begging. These tend to be more misunderstood and slightly more numerous than [[Formal fallacy|formal fallacies]].
==List of informal fallacies==
The Math 101 (Spring 2007) handouts, Department of Mathematical Sciences, Northern Illinois University lists the following informal fallacies:<ref>[http://www.math.niu.edu/~richard/Math101/if1.pdf Informal Fallacies part 1] - Math 101, Spring 2007 handout, Department of Mathematical Sciences, Northern Illinois University</ref><ref>[http://www.math.niu.edu/~richard/Math101/if2.pdf Informal Fallacies part 2] - Math 101, Spring 2007 handout, Department of Mathematical Sciences, Northern Illinois University</ref>
#[[Argumentum ad baculum|Appeal to Force]]: using force or the threat of force to gain acceptance to one's conclusion.
#Abusive ([[Ad hominem]]): instead of trying to disprove the truth of what is asserted, one attacks the person who made the assertion
#Circumstantial: An attempt to prove that an opponent ought to accept an argument because of the special beliefs and circumstances of your opponent.<ref group=note>Not to be confused with [[Bulverism]].</ref>
#[[Argument from ignorance]]: Assertion that a statement is true because it has not been proven false.
#[[Appeal to pity]]: pity is appealed to for the sake of getting a conclusion accepted.
#Appeal to the People ([[Appeal to emotion]]): Attempt to win popular assent by arousing {{wpl|Emotion|the feelings and enthusiasm}} of the multitudes.
#[[Argument from authority#Appeal to respect|False Authority]]: Use of the feeling of respect or admiration people have for a popular person to win assent to a conclusion, especially for matters outside the province of their special fields of authority.
#Accident: Attempt to discredit a general rule by taking a particular exception to that rule. What is true “in general” might not be universally true without qualification, because ''circumstances alter cases''.
#[[Hasty generalization]]: Converse of the fallacy of accident, hasty generalization is when you make a conclusion based on atypical cases.
#False Cause ([[Post hoc, ergo propter hoc]]): [[Correlation does not imply causation|Mistaking what is not the cause for a certain phenomenon]] for the real cause. Sometimes this fallacy occurs when one event precedes a second, [[Magical thinking|and is therefore falsely claimed to be the cause of the second event]].
#[[Begging the question]]: Assume as a premise for your argument the very conclusion you want to prove.
#Complex Question: presume a definite answer to a prior, unasked question.

==[[Fallacy of ambiguity|Fallacies of ambiguity]]==
#Irrelevant Conclusion: Argument purporting to establish a particular conclusion is directed to prove a different conclusion
#[[Equivocation]]: Use of expressions of double meaning in order to mislead.
#Grammatical Construction: Unclear statement because of the loose or awkward way its words are combined.
#Composition: Applying properties of parts of a whole to the whole itself.
#Division: Reverse of composition; what is true for the whole is true of its parts.

Other examples of informal fallacies are: 
*[[Ad hoc]]
*[[Special pleading]]
*[[Weak analogy]]

==In example==
{{syl
|2=Half of all adult [[humans]] can grow beards.
|4=Sophia is an adult human female.
|5=C|6=There is a 50% chance Sophia can grow a beard.
}}

This is not a sound argument because the first premise is irrelevant — an irrelevance which means it is not a valid argument, either: the truth of its premises do not guarantee the truth of its conclusion. As such, it is a formal fallacy.
{{syl
|2=The above argument is valid but unsound
|4=Arguments that are valid but unsound constitute an informal fallacy
|5=C|6=The above argument constitutes an informal fallacy
}}

This is not a sound argument because the first premise is not true — however, if it were true, the argument would be sound. As such, it is an informal fallacy.

==Dixiecrat fallacy==
{{main|States' Rights Democratic Party}}
You know, it's really the [[Democrats]] who are [[racist]]. Want to know why? They're the party who started the [[KKK]]!

====Usage of the Dixiecrat fallacy, and its lost irony====
"Next time one of those stupid [[liberals]] tells you you’re a racist, you tell him it was the dirty, filthy, stinkin’ [[Nigger|ni***r]]-lovin' democRats what started the KKK. You tell 'em that and it'll blow their minds because they'll realize it's the ni***rs that are the real racists."

==Other informal fallacies==
{{collist|2|
*[[Appeal to consequences]]
*[[Appeal to hate]]
*[[Argument from incredulity]]
*[[Didit fallacy]]
*[[Gambler's fallacy]]
*[[God of the gaps]]
*[[Moving the goalposts]]
*[[Quote mining]]
*[[Spotlight fallacy]]
*[[Style over substance]]
*[[Sunk cost]]
*[[Texas sharpshooter fallacy]]
}}

==See also==
*[[Logical fallacy]]
*[[Fallacious argument style]]
*[[Conditional fallacy]]

==Notes==
{{reflist|group=note}}

==References==
{{reflist}}

==External links==
*[http://www.fallacyfiles.org/inforfal.html Informal Fallacy], [[Fallacy Files]]

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[[Category:Informal fallacies| ]]

Categories: Informal fallacies