There are four categories of informal fallacies: fallacies of relevance, fallacies of defective or weak induction, fallacies of presumption, and fallacies of ambiguity.
A logical fallacy ''is not'' the same as [[lie|lying]], although it is still an error if you commit one (and dishonest if you know you are committing one). A ''lie'' in logic is a [[premise]] that one offers while knowing that it is false. Logical fallacies are the beloved debating tactic of liberals; for this reason, it is not advised to debate them unless you have to, as you will only end up frustrated when one of them inevitably claims global warming is true because [[Al Gore]] said so.
==Fallacies of Relevance==
*If person A does not accept P, then Q
*Q is a threat of force
*Therefore , P is true
For example: "If you do not pay me $30 I will break your leg. Therefore you owe me $30." It is fallacious because no amount of force can change the truth or falsity of the initial proposition.
*Person B agrees P, but adds X, where X is an emotional argument unconnected to P
For example: "Yes, [[police|officer]], I realize I was speeding, but you shouldn't give me a ticket because I was racing to see my wife who is in the [[hospital]]." While this argument uses an emotional appeal to convince the officer not to hand out a citation, there is no logical connection between the premise conclusion ("you shouldn't give me a ticket") and the conclusion premise ("I was racing to see my wife").
Appeals to pity are very commonly seen in business. A factory manager may make the following argument: "our factory's overheads are too high, and we cannot maintain our business if we continue here. Therefore we should relocate to an area where labour labor is cheaper." An appeal to pity would be of the following type: "but our workers have bills to pay, families to support, we cannot fire them." That statement may be true, but is fallacious because it is not relevant to the manager's argument.
===Appeal to Consequences===
* Therefore, evolution is false
This argument commits the ''appeal to consequences'' fallacy because it provides no evidence for its conclusion; all it does is appeal to the consequences of believing in evolution. Evolution is not disproven solely because it leads to bad consequences for those who believe in it. The following is a similar example:
* If you believe in evolution, then you'll be more respected in academic circles
* Therefore, evolution is true
This makes an appeal to the positive consequences of believing in evolution, without actually providing any proof of evolution itself. Just because belief in evolution makes you more respected by [[liberal]] professorsin academic circles, this does not mean that evolution is correct. To use a more extreme example, but one doubtless familiar from everyday life, the mere fact that a child's belief in [[Santa Claus]] can have positive consequences does not prove that Santa Claus exists.
A particular form of the appeal to consequences is the [[appeal to personal interest]], which is fallacy of appealing to the personal likes and interests (preferences, prejudices, predispositions, fears, etc.) of others in order to have an argument accepted, when those personal likes and interests are irrelevant to the truth or falsity of the argument.
*Person A is Q
*Q is some derogatory description not related to the argument at hand
*Therefore , P is false
====''Ad hominem tu quoque''====
*Person A argues that P should not happen
*Person A does P
*Therefore , Person A's argument is incorrect
For example: "You can't tell me not to eat cheeseburgers, I just saw you eating one last week!" Another common example is often found in business: "why are you punishing me for dumping waste in the river? My rival does the exact same thing and you don't punish him!" In this case, dumping waste into the river is wrong (and illegal) regardless of how it is enforced for any other company.
===="False Causality" ====
A false causality fallacy is when a person argues that A caused B when there is little evidence to support the claim. Specifically, a false causality is committed when the basis for A causing B is based on some superficial coincidence.
*"Our house was robbed the day after that family moved in, they must have done it!"
In this example, it is only a coincidence that a new family has moved in at the same time another house has been robbed, and this is not grounds for evidence.
====''Poisoning the well''====
*If P then Q
*Q is true
*P is false
*Therefore , Q is false Formally, the error arises in confusing "If P, then Q" with "If and only if P, then Q."
When the origin of ''evidence'' or of ''premises'' is relevant to the reliability of the same, then asking a hearer to "consider the source" is valid. Judges in courts of [[law]], for example, routinely reject as unreliable the testimony of any witness who has demonstrably lied about a point that matters in the case at hand. The facts that such a witness is asserting might still be true, but they cannot stand without corroboration from another, more reliable witness.
===Proof by numbers===
{{main|Argumentum ad populum}}
Also known as "appeal to the people" (Lat: ''ad populum''), this is an argument that a person bases on the numbers of people holding to its conclusion, rather than on the premises that might support that conclusion. An appeal to the people follows the form:
*Person A is in set P
*Person A cites R circumstance, unrelated to P or Q
*Therefore , Person A is not subject to Q
For example: a political or military leader who urges his subjects (or those under his command) to observe "iron rations" without similarly depriving himself leaves himself open to a charge of special pleading.
===Argument from silence===
''Argument from silence'' (in [[Latin]], ''argumentum ab silencio'') or ''argument from ignorance'' (Lat: ''ad ignorantiumignorantiam'') is an assertion which states that, because there is no evidence to support a given argument, the opposite must be true. The fallacy follows the form:
*If P then Q
*P cannot be shown true
*Therefore , Q is false
For example: "Nobody has ever seen God, so clearly he doesn't exist".
====Texas sharpshooter fallacy====
: ''Main article: [[Sharpshooter fallacy]]''
Another form of false cause is the '''Texas sharpshooter fallacy'''. The name comes from a failed marksman who shoots at a barn, draws a bullseye around the biggest cluster of bullet holes, and proclaims himself to be a skilled marksman. In the fallacy, a cluster of data points is assumed to be caused by an apparent cause at that location. The assumption is fallacious because the clustering could be random, or there could be some other cause.<ref>[http://www.fallacyfiles.org/texsharp.html The Texas Sharpshooter Fallacy]</ref> Other ways of explaining the fallacy are that the hypothesis is constructed after the fact to conform to the very data that are used to "test" the hypothesis<ref>[http://www.bun.kyoto-u.ac.jp/~tiseda/works/Mayo-2.html Severe Testing]</ref> and that the same data are used to formulate and test the hypothesis.<ref>[http://www.physicsforums.com/showthread.php?p=3073771#post3073771 Precognition paper to be published in mainstream journal]</ref>
*P
*Therefore , R is true
For example: "Crime rates are high, so we should increase the penalty for drug possession."
*P says Q
*P is an authority in his field
*Therefore , Q is true
A classic example of argument from unqualified authority is a reference to a celebrity or religious leader for their opinion on a matter of science or public policy, when that celebrity or cleric has never adequately studied the subject. A standard argument from authority is often used by evolutionists. A notable scientist claims that evolution is true, and based on that the average person is expected to believe in it as well. This becomes fallacious if the "notable scientist" has never considered alternatives which also provide the answers to the asked questions.
*Some P are Q
*R is in P
*Therefore , R is Q
For example: "You are from [[Ohio]], which is a [[red state]], so you must be a [[Republican]]".
===Contradiction===
:''{{Main article: [[|Contradiction]]''}}
A contradiction is a statement that contradicts its own terms. [[Aristotle]] famously stated that contradictions cannot exist. In any case of a contradiction, some of the premises must be false. A contradiction is an argument which includes in its reasoning:
*P is true
Often the argument is simply [[Fallacy of invincible ignorance|repeated over and over]], and no evidence for support is given. Statements beginning with [[weasel words|expressions ]] such as "It goes without saying that ..." or "Everyone knows ..." are commonly proofs by assertion.
Proof by assertion can also be broken down into several subcategories of fallacies: circular reasoning, infinite regression, manufacturing facts from a theory, and your theory does not work under my theory, so your theory must be wrong.
====Circular reasoning====
:''{{Main article: [[|Circular reasoning]]''}}
[[Circular reasoning]], also called begging the question (Lat: petitio principii), is a form of proof by assertion in which one asserts a premise, then asserts a conclusion from that premise (directly or indirectly), and then tries to show that the last conclusion ''supports'' the original premise.
*Theory A says that if P then Q
*Theory B says that if P then R
*Q and R are mutually exclusive*Therefore , theory A is wrong
For example: "Dinosaurs died 65,000,000 years ago, so the earth couldn't have been created 6,000 years ago."
===Straw man===
:''{{Main article: [[|Straw man fallacy]]}}
A straw man fallacy occurs by first incorrectly attributing an argument to someone, disproving this argument, then claiming that the person was wrong. A straw man argument follows the form:
*If P then Q
*Person A says P
*Therefore , Q
Straw man arguments can sometimes be hard to detect, because a valid statement may be used in a distorted fashion. For example:
===Tautology===
:''{{Main article: [[|tautology]]''}}
A [[tautology]] ([[Greek]] '''ταυτο-''' ''tauto-'', "the same") is an argument that becomes a repetition of a definition. Literally it means "the study of the same." Such an argument, or statement, can prove nothing beyond itself and is useless as a premise.
For example: "The coach said we should eat light, so take your heavy coat off."
'''Un'''equivocal means to leave no doubt about the exact meaning of what is said, to be completely clear, allowing no misunderstanding.
===Moving the Goalposts===
<references/>
==See Alsoalso== * [[Debate:Is infinite regression ever valid as a form of reasoning, or acceptable as a way the universe works, or came to be?Atheism and logical fallacies]]
* [[Liberal logic]]
* [[Specious reasoning]] Debate: * [[Debate:Is infinite regression ever valid as a form of reasoning, or acceptable as a way the universe works, or came to be?]] ==External Linkslinks==
*[http://creationwiki.org/Logical_fallacy Logical fallacy] by [[CreationWiki]]
*[http://www.creationsafaris.com/crevbd.htm The Baloney Detector]
*[http://www.theskepticsguide.org/logicalfallacies.asp SGU-Top 20 Fallacies]
* Sagan, Carl. "The Fine Art of Baloney Detection" in ''The Demon-Haunted World, Science As a Candle in the Dark';' Ballantine: New York, pp. 201-218 201–218 (1996)
{{Liberalism}}
[[Category:Logic]]
[[Category:Logical Fallacies| ]]