User:Threecheersfornick/fallacy

Material fallacies
The taxonomy of material fallacies is widely adopted by modern logicians and is based on that of Aristotle, Organon (Sophistici elenchi). This taxonomy is as follows:

Fallacy of Accident
A Fallacy of Accident is a generalization that disregards exceptions. Also called "destroying the exception", or a dicto simpliciter ad dictum secundum quid.


 * Example
 * Argument: Cutting people is a crime. Surgeons cut people.  Therefore, surgeons are criminals.
 * Problem: Cutting people is only sometimes a crime.
 * Argument: It is illegal for a stranger to enter someone's home uninvited. Firefighters enter people's homes uninvited, therefore firefighters are breaking the law.
 * Problem: The exception does not break nor define the rule.

Converse Fallacy of Accident
A Converse Fallacy of Accident is an argument from a special case to a general rule. Also called "reverse accident", "destroying the exception", or a dicto secundum quid ad dictum simpliciter.
 * Example
 * Argument: Every swan I have seen is white, so it must be true that all swans are white.
 * Problem: What one has seen is a subset of the entire set. One cannot have seen all swans.

Irrelevant Conclusion
An Irrelevant Conclusion diverts attention away from a fact in dispute rather than address it directly. Also called Ignoratio Elenchi, a "red herring".
 * Example
 * Argument: Kim Jong Il believes that war is justifiable, therefore it must be justifiable.
 * Problem: Kim Jong Il can be wrong. (In particular this is an appeal to authority.)
 * Special cases:
 * purely personal considerations (argumentum ad hominem),
 * popular sentiment (argumentum ad populum--appeal to the majority; appeal to loyalty.),
 * fear (argumentum ad baculum),
 * conventional propriety (argumentum ad verecundiam--appeal to authority)
 * to arouse pity for getting one's conclusion accepted (argumentum ad misericordiam)
 * proving the proposition under dispute without any certain proof (argumentum ad ignorantiam)

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 * Affirming the Consequent: draws a conclusion from premises that do not support that conclusion by assuming Q implies P on the basis that P implies Q
 * Example:
 * Argument: If a person runs barefoot, then his feet hurt. Socrates' feet hurt. Therefore, Socrates ran barefoot.
 * Problem: Other things, such as tight sandals, can result in sore feet.
 * Argument: If it rains, the ground is wet. The ground is wet, therefore it rained.
 * Problem: There are other ways by which the ground could get wet (i.e. dew, underground spring, etc.).

~However, the fallacy that deducts the means are considered a post hoc; or a begging the question.
 * Denying the antecedent: draws a conclusion from premises that do not support that conclusion by assuming Not P implies Not Q on the basis that P implies Q
 * Example
 * Argument: If it is raining out, it must be cloudy. It is not raining out. Therefore, it is not cloudy.
 * Problem: There does not have to be rain in order for it to be cloudy.


 * Begging the question: demonstrates a conclusion by means of premises that assume that conclusion.
 * Example
 * Argument: Billy must be telling the truth, because I have heard him say the same thing many times before.
 * Problem: Billy may be consistent in what he says, but he may have been lying the whole time.
 * Argument: The Bible says that God exists and the Bible is always right because it was inspired by God, therefore God exists.
 * Problem: The premises are circular in nature because each premise is assuming the other.
 * Also called Petitio Principii, Circulus in Probando, arguing in a circle, assuming the answer. It is worth noting that a circular argument may actually be both logically and factually correct. Circularity itself has no bearing on the truth or falseness of the argument at all, the fallacy is to use a circular argument as a proof of truth.


 * Fallacy of False Cause or Non Sequitur: incorrectly assumes one thing is the cause of another. Non Sequitur is Latin for "It does not follow."
 * Example
 * Argument: Our nation will prevail because God is great.
 * Problem: There is no necessary cause and effect between God's greatness and a nation prevailing. Simply because God can be considered great does not mean a nation will prevail.
 * Special cases
 * post hoc ergo propter hoc: believing that temporal succession implies a causal relation.
 * Example
 * Argument: After my son had his vaccine, he developed autism. Therefore, the vaccine caused autism.
 * Problem: The characteristics of autism may generally become noticeable at the age just following the typical age children receive vaccinations.
 * cum hoc ergo propter hoc: believing that happenstance implies causal relation (aka fallacy of causation versus correlation: assumes that correlation implies causation).
 * Example
 * Argument: More cows die in India in the summer months. More ice cream is consumed in summer months.  Therefore, the consumption of ice cream in the summer months is killing Indian cows.
 * Problem: It is hotter in the summer, resulting in both the death of cows and the consumption of ice cream.


 * Fallacy of Many Questions or loaded question: groups more than one question in the form of a single question
 * Example
 * Argument: Is it true that you no longer beat your wife?
 * Problem: A yes or no answer will still be an admission of guilt to beating your wife at some point. (See also Mu.)
 * Also called Plurium Interrogationum and other terms


 * Straw man: A straw man argument is an informal fallacy based on misrepresentation of an opponent's position.
 * Example
 * Person A claims: Sunny days are good.
 * Argument Person B: If all days were sunny, we'd never have rain, and without rain, we'd have famine and death. You are obviously wrong.
 * Problem: B has falsely framed A's claim to imply that A says that only sunny days are good, and has argued against that assertion instead of the assertion A has made.

Example
Consider the following argument which claims to prove that pie is delicious: This particular argument has the form of a categorical syllogism. In this case "Pie is food" and "Food is delicious" act as premises. The first assumption is almost true by definition: pie is a foodstuff edible by humans. The second assumption is less clear; it could mean any one of the following:
 * 1) Pie is food.
 * 2) Food is delicious.
 * 3) Therefore, pie is delicious.


 * All food is delicious.
 * One particular type of food is delicious.
 * Most food is delicious.
 * Some food is delicious.

It may also imply that anything not delicious can not be considered food (equivalent to the first statement under formal logic)

Only the first interpretation validates the second premise. If the interlocutor grants this interpretation then the argument is valid; the interlocutor is essentially conceding the point. However, the interlocutor is more likely to believe that some food is not delicious. In this case, the speaker must prove the assertion that pie is a unique type of universally delicious food. This is a disguised form of the original thesis. In this case, the speaker commits the logical fallacy of begging the question.