Saturday, August 13, 2011

Logic: Fallacies

 

Equivocation

Equivocation occurs when a word is misconstrued in a sentence or argument for two or more meanings.

Example 1:

A fan can cool off a person dripping in sweat.

Juan de la Cruz is a fan of western actors.

Therefore, Juan de la Cruz can cool off western actors.

Explanation:

The term “fan” is ambiguous in the argument. The fan in the first statement refers to a tool to move air while a fan in the case of Juan de la Cruz refers to being an enthusiastic admirer of a celebrity.

Example 2:

Adam is the fastest runner in the world because he is first in the human race.

Explanation:

The word being misunderstood in this example is “race,” as a competition of speed  and as humanity as a whole.

Amphiboly

In amphiboly or amphibology, confusion is caused by error in grammar construction. Mentioning an ambiguous statement as premises often leads to misinterpretation and therefore an illogical conclusion.

Example 1:

Gary played his violin while Joey was playing his piano.

Explanation:

There is confusion regarding to who the owner of the piano and/or the violin is. The pronoun “his”, especially the second one, can ambiguously refer to either Gary or Joey.

Example 2:

Wanted: A girl for cooking.

Explanation:

The correct statement for such wanted sign is “Wanted: A girl cook.” The former statement rather suggests that the girl is to be cooked.

Accent

Whereas occurrence amphiboly lies on grammar faults (written), a fallacy of accent is committed when there is faulty emphasis on certain parts of the sentence. In other words, it is the spoken equivalent of amphibology.

Example 1:

Every man has the right to bear arms.

Explanation:

If emphasis on accent is found on “bear arms”, the statement means every person’s entitlement to arms of bears. If on the hand accent is simply focused on the word “bear”, the right therefore refers to possession of weapons, especially guns.

Example 2:

The teacher said the class is lazy.

Explanation:

The statement can be spoken out loud differently. It can either mean that the teacher is lazy according to the class or the class is lazy as mentioned by the teacher.

Composition

The fallacy of composition is committed when a characteristic of a part is wrongly attributed to the whole.

Example 1:

This car has a state-of-the-art engine. Therefore the car is excellent.

Explanation:

While the engine of the car may be a product of the latest technology, the whole car does not necessarily follow as most high-tech. Its other parts might be obsolete or of subpar quality.

Example 2:

Sodium and chloride are poisonous substances.

Sodium choride or rock salt is made of sodium and chloride.

Therefore, rock salt is a poisonous substance.

Explanation:

Sodium and chloride being poisonous is incorrectly misapplied to rock salt which is perfectly suitable for consumption by humans.

Naturally there are attributes of parts that can be transferred to the whole.  For example,

Every atom in this cup has a mass.

Therefore, this cup has mass.

Division

Division is the converse of composition, where the properties of the whole is incorrectly assumed as also properties of the parts.

Example 1:

In normal room temperature, water is liquid. Therefore, hydrogen and oxygen, the elements that compose water, are liquid in normal room temperature.

Explanation:

While water and its elements can be solid, liquid or gas in certain conditions, they have a default phase in normal temperature. Indeed water in such condition is liquid. However, oxygen and hydrogen are expected to be gas.

Example 2:

Some whole jigsaws form a square.

Therefore each puzzle piece of those jigsaws are square.

Explanation:

Jigsaw pieces are shaped differently in order to help players tell if they placed the pieces in the correct location.

Figure of Speech

With the fallacy of figure of speech or parallel-word construction, the argument is based on the implication of similarity in word structure leading to similarity in meaning.

Example 1:

Since the opposite of illiterate is literate, then the opposite of liquid is illiquid.

Explanation:

There is similarity between literature and liquid in the sense that adding a prefix ill- before them creates a new meaning. However, while the former, illegitimate, is the contradiction of literate which means the ability to read and write, illiquid is not the opposite of liquid. Illiquid is a term in accountancy which means hard to convert into cash.

Example 2:

Since the opposite of immobile is mobile, then the opposite of inflammable is flammable.

Explanation:

Similar to the first example, the fallacy exists in the similarity in word structure. Inflammable is synonymous with, not opposite to,  flammable.

Accident

In fallacy of accident, the essence (the necessary elements) and accidents (miscellaneous characteristics) of a thing are confused; also, the abuse of a thing becomes reason to forbid it.

Example 1:

Mammals do not lay eggs.

Platypuses lay eggs.

Platypuses are not mammals.

Explanation:

The inability to lay eggs is mistakenly considered as essential to being a mammal. However, there are actually mammals called “monotremes,” which include platypuses, that can lay eggs.

Example 2:

Eating lollipop may cause tooth ache.

Therefore, no one should eat lollipops.

Example 3:

Gambling can be addicting.

Hence, no one should gamble.

Explanation:

Examples 2 and 3 are assuming that because things like lollipop and gambling can be abused, then it must be illegalized or forbidden.

Absolute Statement

In absolute and qualified statement, the validity of something that is generally true is misapplied to a specific exception. One also commits such fallacy when a special case accepted as true is incorrectly used to create a general statement.

Example 1:

Some drugs help promote a person’s well-being.

Therefore, indulging to cocaine is encouraged.

Explanation:

In general, drugs are made to improve the health of people. The cocaine drug is exception to this observation. Cocaine is addictive and can cause health problems when abused.

Example 2:

Incest is a serious taboo.

Therefore, sex is wrong.

Explanation:

Sex is essential for the propagation of the human race.

Begging the Question

In the fallacy of begging the question, the truth of the conclusion remains to be proved.

Also known as petitio principii, the fallacy takes the following forms:

Arguing in a circle (or circulus in probando) refers to the conclusion which in itself is the one being proved. The conclusion may merely restate the premise.

Example 1:

We should ban marijuana because it is an illegal substance.

Explanation:

The conclusion, which is to ban marijuana, is simply a restatement of the assertion that marijuana is an illegal substance. Something that is illegal is already presumed to be banned.

Example 2:

Capital punishment is justifiable for the crimes of murder and kidnapping because it is quite legitimate and appropriate that someone be put to death for such heinous crime.

Explanation:

To say it is legitimate and appropriate means it is justifiable. Also, to put someone to death is the very definition of capital punishment.

Assumption without proof (or assumptio non probata) refers to using an incorrect statement or principle as an implied premise or is presumed to be true for the sake of the argument. The essential premise is missing or ignored to pass a wrong conclusion.

Example 1:

Murder is condemned by society.

Therefore, the progress of stem cell research must be stagnated.

Explanation:

The argument begs the question if dissecting fetuses and embryos, the abundant sources of stem cells, is murder.

Example 2:

Bruce is a tough and brave boy.

Therefore, Bruce does not cry.

Explanation:

The argument assumes that a boy who is tough and brave does not cry.

Complex question (or loaded question) refers to questioning that already assumes something in advance as the truth. In this fallacy, the arguer attempts to persuade by trapping the listener or reader with a question that forces them to respond with a desired answer, thereby completing the argument to the arguer’s favor

Example 1:

Didn’t your computer blow up because of your own inexperience?

Explanation:

The asker intends to trap the computer owner into admission of being a computer illiterate.

Example 2:

Have you stopped cheating during exams?

Explanation:

Whether the reply is a simple yes or no, the one being asked is accused of being a cheater.