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Line 7: − ==Catalog of Logical Fallacies==+ − + + + + + + + + + + + + + + + + + + + + + − + + + + + + + + + + + + + + + + + + + + + + + + + + + + − + − + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + − Overgeneralization also is the central problem in trying to conclude something about a population from a non-representative sample, or about a larger group from a non-representative subset of that group.+ − + + + + + + + + + + + + + + + + + + + + − + + + + + + + + + + + + + + + + + + + + + + + + − A classic example of argument from 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. This kind of argument also appears in commercial advertising or political electioneering.+ + − + − 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. "Ninety nine point nine percent of all respondents can't be wrong" is the classic phraseology. One does not effectively disprove such an argument by challenging the numbers. Instead, one reminds the other person that the numbers of people holding to any given conclusion are irrelevant to establishing the truth or falsehood of that conclusion. [[History]] is in fact replete with multiple examples, too many to mention here, of conclusions that memorable [[science|scientists]] and other great discoverers have shown to be false even though large numbers of people believed them. [[Antoine Lavoisier]], who disproved "phlogiston" as the principle of fire, was one such person. [[Christopher Columbus]] and [[Ferdinand Magellan]] make two more.+ + + − An argument that states something as true without offering supporting evidence or attempting to construct a valid argument. The typical form of this "argument" is the "conclusion" of a [[non sequitur]].+ − ===Circular reasoning===+ − [[Circular reasoning]] 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. − + − Argument from silence (in [[Latin]], ''argumentum ab silencio'') is an assertion that a proposition is false merely because no one has yet asserted evidence to confirm it--or that a proposition is true merely because no one has yet asserted evidence to contradict it. "The absence of evidence does not constitute evidence of absence." The charge of argument from silence applies in a situation in which ''no reasonable attempt has yet been made'' to develop evidence to confirm or contradict the proposition in question.+ + + + + + + + + + + + + + + + + + + + + + − This is the opposite extreme from "manufacturing facts to support a theory," described below. The best aid to striking a balance that avoids these two opposing fallacies is [[Occam's razor]].+ − ===Proving too much===+ − A form of overgeneralization in which one attempts to use a set of premises to sustain more conclusions than he can reasonably sustain using the argument presented. − + − The unequal use of a criterion, and its different application in different cases. This is actually a form of [[hypocrisy]].+ − ===Your theory does not work under my theory, so your theory must be wrong===+ − − The judgment of a theory by the premises and assumptions of another theory, rather than against its own premises and assumptions. This is a variation on proof-by-assertion.+ + + − ===Manufacturing facts from a theory===+ − − The assertion as fact of an undemonstrated, unobserved idea for no better reason than that a given theory requires that fact. We deal here with the assumption of a fact ''not in evidence.'' In the early stages of formulating a model, this sort of behavior is acceptable. But when repeated efforts to demonstrate such a new fact ''have failed'', the proper logical response is to discard or revise the theory, and not merely to assume that the "fact" still exists and "someone hasn't tried hard enough" to find it. This is ''especially'' true when someone develops evidence that the inferred "fact" ''could not possibly exist.''+ + − This is yet another form of proof-by-assertion, and is the source of many controversies in modern [[astronomy]], some of them strikingly bitter.+ − ===Genetic fallacy===+ − In general, this is the attempt to aver (that is, assert as true) or reject a theory by citing its origins as either reputable or disreputable. The usual expression of this fallacy is "Consider the source!" Thus it becomes a form either of ''argumentum ab auctoritate'' or of ''argumentum ad hominem'', depending on whether one seeks to verify or disprove the theory by this method.+ + − 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.+ − But when corroboration is established, the origins of a conclusion, however tainted, become irrelevant.+ + − As an example, [[Gregor Mendel]] established the genetic theory that remains current today, even though Mendel's experimental technique was badly flawed, and he even stands accused of falsifying key data. But succeeding [[science|scientists]], using accepted methods of verification and statistical assessment, have achieved results consistent with this theory. Thus the theory remains valid even though Mendel's original presentation was fraudulent. Any attempt today to discredit Mendel's theory on account of Mendel's sloppy methods would be an example of a genetic fallacy.<ref name=Genetic>[http://www.fallacyfiles.org/genefall.html Genetic Fallacy] on [http://www.fallacyfiles.org/ The Fallacy Files]</ref>+ + + − + − A [[contradiction]] is a statement that contradicts its own terms. [[Aristotle]] famously stated that contradictions cannot exist. In any case of a contradition, some of the premises must be false.+ + + + + + + + + − Contradictions normally form part of a proof by ''exclusion''. But contradictory arguments are some of the most common flawed arguments, and are closely akin to double standards (see above).+ − + + + + + − + − : ''Main Article: [[Loaded question]]''+ − A [[loaded question]] is a question that assumes facts, usually unflattering, that are not in evidence, with the intent of trapping the other person into admitting those facts. The classic loaded-question example is "When did you stop beating your wife?" Another example is, "Do you disbelieve in [[global warming]], which 99.9 percent of all reputable scientists now accept?" (It is also an example of proof by numbers of adherents.)+ − + − : ''Main Article: [[Special pleading]]''+ − [[Special pleading]] means applying to other people a set of standards that one is not willing to apply to oneself, without offering sufficient grounds, called the ''relevant difference'', to support such exemption. Special pleading is a special case of the double standard, and is one of the most despicable forms of hypocrisy. 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.+
→Catalog of Logical Fallacies: add changes
The following is a catalog of informal logical fallacies, with each one given a separate heading, to make them easier to cite in other articles.
The following is a catalog of informal logical fallacies, with each one given a separate heading, to make them easier to cite in other articles.
__TOC__
===Argumentum ad hominem===
==Fallacies of Relevance==
Fallacies of relevance are fallacies which are due to a lack of a relevant logical connection between premise and conclusion.
===Appeal to force===
An appeal to force (Lat: ''argumentum ad baculum'') is an argument which uses a threat of violence or force as a justification for the conclusion. An appeal to force argument follows the form:
*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."
===Appeal to pity===
Also called emotional appeal, (Lat: ''ad misericordiam'') this fallacy is characterized by a use of emotion as a justification for the conclusion. An appeal to pity follows the form:
*Person A argues that P
*Circumstance Q has happened to person P
*Therefore P is true
For example: "Yes, 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 ("you shouldn't give me a ticket") and the conclusion ("I was racing to see my wife").
===''Argumentum ad hominem''===
: ''Main Article: [[Ad hominem]]''
: ''Main Article: [[Ad hominem]]''
([[Latin]]: "Argument directed toward the man"); An argument that attacks the character of one holding a contrary view, rather than attacking the view itself. ''Name-calling'' is a particularly crude form of this fallacy. ''Argumentum ad hominem'' is usually an attempt to accuse the other person of lying without saying so directly, or saying that his premises are somehow incompetent, irrelevant, or immaterial, or simply unreliable because they are self-serving. However, this is not good logic. If one suspects another of lying, then one should attempt to disprove the premises. One can raise a ''suspicion'' of deliberate falsehood on the part of another who has offered deliberate falsehood in the past. But the most that that can accomplish is to suggest that the other person's premises are unreliable and therefore require third-party corroboration.
''Ad hominem'' arguments (Lat: "argument directed toward the man") fall into two forms: ''ad hominem'' abusive and ''ad hominem tu quoque'' (circumstantial).
====''Ad hominem'' abusive====
An ''ad hominem'' is an argument which tries to disprove another argument by attacking the person who made it, rather than by focusing on the actual logical reasoning. The goal of an ''ad hominem'' argument is usually to take focus off of the actual argument by calling attention to a flaw of the person making it. This form of argument follows the form:
*Person A argues that P
*Person A is Q
*Q is some derogatory description not related to the argument at hand
*Therefore P is false
For example: "We all know that George beats his wife, so obviously he's wrong when he says that we should vote against this proposition." This is fallacious reasoning because the premise ("George beats his wife") does not have a logical link with the conclusion ("George is wrong").
====''Ad hominem tu quoque''====
A ''tu quoque'' argument (Lat: "you're another") is one which argues that, because someone does that which they are arguing against, that person must be wrong. This form of argument follows the form:
*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 opponent 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.
===Genetic fallacy===
In general, this is the attempt to assert or reject a theory by citing its origins as either reputable or disreputable. The usual expression of this fallacy is "consider the source!" Thus it becomes a form either of ''argumentum ab auctoritate'' or of ''argumentum ad hominem'', depending on whether one seeks to verify or disprove the theory by this method. This type of argument follows the form:
*If P then Q
*Q is true
*P is false
*Therefore Q is false
===Overgeneralization===
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.
An argument that attempts to apply a principle to circumstances beyond the scope of its original formulation or of any reliable demonstration. The application of [[Isaac Newton]]'s original theory of relative velocity (which is that it was simply additive) to speeds approaching that of light was an overgeneralization, as [[relativity]] would later show.
But when corroboration is established, the origins of a conclusion, however tainted, become irrelevant.
As an example, [[Gregor Mendel]] established the genetic theory that remains current today, even though Mendel's experimental technique was badly flawed, and he even stands accused of falsifying key data. But succeeding [[science|scientists]], using accepted methods of verification and statistical assessment, have achieved results consistent with this theory. Thus the theory remains valid even though Mendel's original presentation was fraudulent. Any attempt today to discredit Mendel's theory on account of Mendel's sloppy methods would be an example of a genetic fallacy.<ref name=Genetic>[http://www.fallacyfiles.org/genefall.html Genetic Fallacy] on [http://www.fallacyfiles.org/ The Fallacy Files]</ref>
===Proof by numbers===
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:
:Most people believe P
:Therefore P is true
"Ninety nine point nine percent of all respondents can't be wrong" is the classic phraseology of this fallacy One does not effectively disprove such an argument by challenging the numbers. Instead, one reminds the other person that the numbers of people holding to any given conclusion are irrelevant to establishing the truth or falsehood of that conclusion. [[History]] is in fact replete with multiple examples of conclusions that memorable [[science|scientists]] and other great discoverers have shown to be false even though large numbers of people believed them. [[Antoine Lavoisier]], who disproved "phlogiston" as the principle of fire, was one such person. [[Christopher Columbus]] and [[Ferdinand Magellan]] are two others.
===Special pleading===
: ''Main Article: [[Special pleading]]''
[[Special pleading]] means applying to other people a set of standards that one is not willing to apply to oneself, without offering sufficient grounds, called the ''relevant difference'', to support such exemption. Special pleading follows the form:
*If Person X is in set P then Q happens to person X
*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.
==Fallacies of Defective or Weak Induction==
Fallacies of defective or weak induction are fallacies which are due to a lack of understanding for how well premises lead to a conclusion.
===Argument from silence===
''Argument from silence'' (in [[Latin]], ''argumentum ab silencio'') or ''argument from ignorance'' (Lat: ''ad ignorantium'') 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".
This fallacy is often associated with and best remembered by the phrase: "the absence of evidence does not constitute evidence of absence."
===False cause===
False cause (Lat: ''non causa pro causa'') is a fallacy which arises when a poor cause/effect link is used within an argument, especially if coincidence or chance are not taken into account. The fallacy follows the form:
*P causes Q (faulty reasoning)
*P is true
*Therefore Q is true
For example: "I used to be a well paid teacher until I started being a tougher grader. When my students' grades went down, so did my salary." While this sounds like a logical explanation, not all factors are taken into account. For example, the teacher's school could have been subject to budget cuts, or maybe the teacher was overpaid at first and now his salary corrects his true worth.
====''Post hoc ergo propter hoc''====
''Post hoc ergo propter hoc'' (Lat: "after the thing, therefore because of the thing") is a subcategory of false cause fallacies. In this type of argument, a close temporal proximity is used as a justification of a cause/effect relationship. ''Post hoc ergo propter hoc'' arguments follow the form:
*P happened, and then Q happened
*Therefore P caused Q
For example: "Right around the time the sun goes up my alarm clock goes off, so the sun causes my alarm clock to go off." Clearly this is not the case.
===Non sequitur===
===Non sequitur===
: ''Main Article: [[Non sequitur]]''
: ''Main Article: [[Non sequitur]]''
([[Latin]]: "It does not follow"); An argument which moves from a premise to a conclusion without showing a valid connection.
A ''non sequitur'' (Lat: "It does not follow") is an argument which moves from a premise to a conclusion without showing a valid connection, or sometimes any connection at all. This form of argument follows the form:
*P
*Therefore R is true
For example: "Crime rates are high, so we should increase the penalty for drug possession."
===Overgeneralization===
Overgeneralization (also called hasty generalization or converse accident) is an error in reasoning which comes about by making a logical leap far greater than what the data allows. Overgeneralization follows the form:
*P is Q
*P is in R
*Therefore R is Q
For example: "I just read that three kids were arrested yesterday for drug possession. Teens in this country are really going downhill!"
Overgeneralization the central problem in trying to conclude something about a population from a non-representative sample, or about a larger group from a non-representative subset of that group.
====Proving too much====
Proving too much is a form of overgeneralization in which one attempts to use a set of premises to sustain more conclusions than he can reasonably sustain using the argument presented.
===Proof by authority===
===Proof by authority===
Also known as ''argumentum ab auctoritate'' ([[Latin]] "Argument proceeding from clout"), this is an argument that a person bases on authority, either his own or that of another person, rather than on the merits of the position. When the authority involved is a relevant source who has access to more information about the topic than the people discussing it, then the argument becomes a ''citation.'' However, a valid citation must be in an area of study, research, or mental discipline in which the authority being cited is a recognized [[expert]].
Also known as ''argumentum ab auctoritate'' ("argument proceeding from clout") or ''argumentum ad verecundiam'' ("appeal to unqualified authority"), this is an argument that a person bases on authority, either his own or that of another person, rather than on the merits of the position. When the authority involved is a relevant source who has access to more information about the topic than the people discussing it, then the argument becomes a ''citation.'' However, a valid citation must be in an area of study, research, or mental discipline in which the authority being cited is a recognized [[expert]].
*P says Q
*P is an authority in his field
*Therefore Q is true
A classic example of argument from 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. This kind of argument also often appears in commercial advertising or political electioneering.
==Fallacies of Presumption==
Fallacies of presumption are fallacies in which an unstated or shaky presumption is made.
===Accident===
The fallacy of accident occurs when a generalization is inappropriately applied to an individual. A fallacy of accident follows the form:
*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
*Not P
===Proof by numbers===
===Loaded question===
: ''Main Article: [[Loaded question]]''
A [[loaded question]] is a question that assumes facts, usually unflattering, that are not in evidence, with the intent of trapping the other person into admitting those facts. The classic loaded-question example is "When did you stop beating your wife?" Another example is, "Do you disbelieve in [[global warming]], which 99.9 percent of all reputable scientists now accept?"
===Proof by assertion===
===Proof by assertion===
Proof by assertion is an argument that states something as true without offering supporting evidence or attempting to construct a valid argument. This form of argument follows the form:
*P is true
===Argument from silence===
Often the argument is simply repeated over and over, and no evidence for support is given.
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.
====Infinite regression====
: ''Main Article: [[Infinite regression]]''
An infinite regression results when one asserts that a given event caused another, and yet that first event requires another, identical event, to cause ''it.'' An infinite regression follows the form:
*P<sub>1</sub> causes Q<sub>1</sub>
*Q<sub>2</sub> causes P<sub>1</sub>
*P<sub>3</sub> causes Q<sub>2</sub>
*Q<sub>4</sub> causes P<sub>3</sub>
*And so on, forever
For example: [[Panspermia]], an alternative to [[abiogenesis]] as a proposition about the origin of life, suffers from the infinite-regression flaw so long as it fails to state positively what conditions could have brought about an origin of life on a planet other than the earth, ''other than'' the alleged mechanism of the "seeding" of life on the earth itself.
====Manufacturing facts from a theory====
Manufacturing facts from a theory is the assertion as fact of an undemonstrated, unobserved idea for no better reason than that a given theory requires that fact.
In the early stages of formulating a model, this sort of behavior is acceptable. But when repeated efforts to demonstrate such a new fact have failed, the proper logical response is to discard or revise the theory, and not merely to assume that the "fact" still exists and someone hasn't tried hard enough to find it. This is especially true when someone develops evidence that the inferred "fact" could not possibly exist.
===Double standard===
====Your theory does not work under my theory, so your theory must be wrong====
: ''Main article: [[Your theory does not work under my theory, so your theory must be wrong]]'' <!-- note: a Google search for this phrase show that it is exclusive to CreationWiki (well, and now Conservapedia) -->
This fallacy occurs when one theory is judged by the premises and assumptions of another theory, rather than against its own premises and assumptions. This form of fallacy follows the form:
: ''Main article: [[Your theory does not work under my theory, so your theory must be wrong]]''
*Theory A says that if P then Q
*Theory B says that if P then R
*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."
: ''Main article: [[Manufacturing facts from a theory]]''
===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:
*Person A believes that a military program should be cut
*Person B argues that since Person A wants to cut military funding, he wants to leave the country defenseless to attack
This is fallacious reasoning, because there is no way to know ''why'' person A believes what he does, and Person B has used one reason which suits his own purpose. For example, it's quite possible that Person A wants to cut the program because he wants to change the funding to something which he thinks does a ''better'' job at defending the country.
===Tautology===
===Tautology===
:''Main article: [[tautology]]''
A [[tautology]] ([[Greek]] '''ταυτα''' ''tauta'', "these") is an argument that becomes a repetition of a definition. Literally it means "the study of this" or "the study of these." Such an argument, or statement, can prove nothing beyond itself and is useless as a premise.
A [[tautology]] ([[Greek]] '''ταυτα''' ''tauta'', "these") is an argument that becomes a repetition of a definition. Literally it means "the study of this" or "the study of these." Such an argument, or statement, can prove nothing beyond itself and is useless as a premise.
===Contradiction===
==Fallacies of Ambiguity==
Fallacies of ambiguity are fallacies which arise from ambiguity in language used.
===Amphiboli===
Amphiboli is an ambiguity which arises though loose or awkward phrasing:
For example: "Save soap and waste paper".
===Composition===
The fallacy of composition occurs when the parts of a whole are incorrectly used to describe the whole.
For example: "Since one of the battleships is ready to deploy, the whole fleet is ready to deploy".
===Conflation===
===Conflation===
[[Conflation]] is the treatment of two different concepts as one. The most common form of conflation informs the proverbial accusation, "You are comparing apples to oranges."
:''Main article: [[Conflation]]''
Conflation is the treatment of two different concepts as one.
For example: "Comparing apples to oranges".
===Loaded question===
===Division===
The fallacy of division occurs when it is argued that what is true for the whole must be true for its parts.
For example: "That company is very important. Since Joe works at that company, he must be very important."
===Special pleading===
===Equivocation===
Equivocation is the use of word with multiple meanings, and then using a different meaning in the conclusion than in the premise.
For example: "The coach said we should eat light, so take your heavy coat off."
== Related examples of improper reasoning ==
== Related examples of improper reasoning ==