1. Rules of Syllogism – There are five rules that govern the categorical syllogism:

Rule 1: There must be three terms and only three – the major term, theminor term, and the middle term. If there are only two terms the relationship between these two cannot be established. And if there were more than three terms this would violate the structure of the categorical syllogism.

Animals are living beings.Plants are heavenly bodies.Therefore…Stones are minerals.Minerals are stones.Therefore…A widower is a man.A man is either male or female.

Therefore, a widower is either male or female.

Rule 2: Each term must occur twice in the syllogism: the major must occur in the conclusion and in one premise, the minor in the conclusion and in one premise; the middle in both premise but not in the conclusion. There must therefore be a total of three propositions in the syllogism.

Rule 3: The middle term must be distributed at least once. If the middle term is particular in both premises it might stand for a different portion of its extension in each occurrence and thus be equivalent to two terms.

All sharks are fish.All salmon are fish.Therefore, all salmons are sharks.Many rich men oppress the poor.Jones is a rich man.

Therefore, Jones oppresses the poor.

Rule 4: The major and minor terms may not be universal in the conclusion unless they are universal in the premises. If a term is distributed in the conclusion then it must be distributed first in the premise.

There is an illicit major term if the major term is universal in the conclusion but particular in the premise:

All horses are animals.All dogs are not horses.Therefore, all dogs are not animals.There is an illicit minor term if the minor term is universal in the conclusion but particular in the premise:All tigers are mammals.All mammals are animals.

Therefore, all animals are tigers.

The rationale behind this rule is that we may not conclude about all the inferiors of a term if the premises have given us information about only some of them. The key to detect a violation of this rule is to examine the conclusion. If there is no term that is distributed in the conclusion then this rule could not have been violated. If one or both terms in the conclusion are distributed there is possibility of the rule having been violated. If a term is distributed both in the premise and the conclusion there is no violation of this rule.

Rule 5: If both premises are affirmative, the conclusion must be affirmative. The reason for this rule is that affirmative premises either unite the minor or major terms, or else do not bring them into relationship with each other at all.

All sins are detestable.All pretenses are a sin.Therefore, all pretenses are not detestable.There is a need to be cautious about apparently affirmative or negative propositions:Animals differ from angels.Man is an animal.

Therefore, a man is not a horse.

Rule 6: If one premise is affirmative and the other negative, the conclusion must be negative.

All crows are birds.All wolves are not crows.Therefore, all wolves are birds.Some premises are apparently affirmatives but actually negative and therefore yield a valid conclusion:Dogs are not cats.Greyhounds are dogs.Therefore, greyhounds differ from cats.

Rule 7: If both premises are negative – and not equivalently affirmative – there can be no conclusion.

Reptiles are not mammals.Dogs are not reptiles.

Therefore…

Rule 8: If both premises are particular there can be no conclusion.

Begging the Question - This type of fallacy is when the conclusion of an argument is assumed in the phrasing of the question itself.

For example: “If aliens didn’t steal my newspaper, who did?” (assume that the newspaper was actually stolen). Appeal to Authority - This type of fallacy is also referred to as Argumentum ad Verecundia (argument

from modesty). In this case, rather than focusing on the merits of an argument, the arguer will try to attach their argument to a person of authority in an attempt to give credence to their argument.For example: “Well, Isaac Newton believed in Alchemy, do you think you know more than Isaac Newton?”

Attacking the Person - Also known as Argumentum ad Hominem (argument against the man), this is quite a common occurrence in debates and refers to a person who substitutes a rebuttal with a personal insult.For example: “Don’t listen to Eddie’s arguments on education, he’s an idiot.”

Description of Composition

The fallacy of Composition is committed when a conclusion is drawn about a whole based on the features of its constituents when, in fact, no justification provided for the inference. There are actually two types of this fallacy, both of which are known by the same name (because of the high degree of similarity).

The first type of fallacy of Composition arises when a person reasons from the characteristics of individual members of a class or group to a conclusion regarding the characteristics of the entire class or group (taken as a whole). More formally, the "reasoning" would look something like this.

1. Individual F things have characteristics A, B, C, etc.

2. Therefore, the (whole) class of F things has characteristics A, B, C, etc.

This line of reasoning is fallacious because the mere fact that individuals have certain characteristics does not, in itself, guarantee that the class (taken as a whole) has those characteristics.

It is important to note that drawing an inference about the characteristics of a class based on the characteristics of its individual members is not always fallacious. In some cases, sufficient justification can be provided to warrant the conclusion. For example, it is true that an individual rich person has more wealth than an individual poor person. In some nations (such as the US) it is true that the class of wealthy people has more wealth as a whole than does the class of poor people. In this case, the evidence used would warrant the inference and the fallacy of Composition would not be committed.

The second type of fallacy of Composition is committed when it is concluded that what is true of the parts of a whole must be true of the whole without there being adequate justification for the claim. More formally, the line of "reasoning" would be as follows:

1. The parts of the whole X have characteristics A, B, C, etc.2. Therefore the whole X must have characteristics A, B, C.

Examples of Composition

1. A main battle tank uses more fuel than a car. Therefore, the main battle tanks use up more of the available fuel in the world than do all the cars.

2. A tiger eats more food than a human being. Therefore, tigers, as a group, eat more food than do all the humans on the earth.

3. Atoms are colorless. Cats are made of atoms, so cats are colorless.

4. "Every player on the team is a superstar and a great player, so the team is a great team." This is fallacious since the superstars might not be able to play together very well and hence they could be a lousy team.

5. "Each part of the show, from the special effects to the acting is a masterpiece. So, the whole show is a masterpiece." This is fallacious since a show could have great acting, great special effects and such, yet still fail to "come together" to make a masterpiece.

6. "Come on, you like beef, potatoes, and green beens, so you will like this beef, potato, and green been casserole." This is fallacious for the same reason that the following is fallacious: "You like eggs, icecream, pizza, cake, fish, jello, chicken, taco sauce, soda, oranges, milk, egg rolls, and yogurt so you must like this yummy dish made out of all of them."

7. Sodium and Chloride are both dangerous to humans. Therefore any combination of sodium and chloride will be dangerous to humans.

8. Ad Hominem--Attacking the individual instead of the argument.1. Example :  You are so stupid your argument couldn't possibly be true.2. Example :  I figured that you couldn't possibly get it right, so I ignored your comment.9. Appeal to Force--Telling the hearer that something bad will happen to him if he does not accept the

argument. 1. Example :  If you don't want to get beaten up, you will agree with what I say.2. Example :  Convert or die.10. Appeal to Pity--Urging the hearer to accept the argument based upon an appeal to emotions, sympathy,

etc. 

1. Example :  You owe me big time because I really stuck my neck out for you.2. Example :  Oh come on, I've been sick.  That's why I missed the deadline.11. Begging the Question--Assuming the thing to be true that you are trying to prove.  It is circular.

1. Example :  God exists because the Bible says so.  The Bible is inspired.  Therefore, we know that God exists.

2. Example :  I am a good worker because Frank says so.  How can we trust Frank?  Simple:  I will vouch for him.

12. Fallacy of Division--Assuming that what is true of the whole is true for the parts.1. Example :  That car is blue.  Therefore, its engine is blue.2. Example :  Your family is weird.  That means that you are weird, too.

13. Fallacy of Equivocation--Using the same term in an argument in different places but the word has different meanings.

1. Example :  A bird in the hand is worth two in the bush.  Therefore, a bird is worth more than President Bush.

2. Example :  Evolution states that one species can change into another.  We see that cars have evolved into different styles.  Therefore, since evolution is a fact in cars, it is true in species.

Description of Ad Hominem

Translated from Latin to English, "Ad Hominem" means "against the man" or "against the person."

An Ad Hominem is a general category of fallacies in which a claim or argument is rejected on the basis of some irrelevant fact about the author of or the person presenting the claim or argument. Typically, this fallacy involves two steps. First, an attack against the character of person making the claim, her circumstances, or her actions is made (or the character, circumstances, or actions of the person reporting the claim). Second, this attack is taken to be evidence against the claim or argument the person in question is making (or presenting). This type of "argument" has the following form:

1. Person A makes claim X.2. Person B makes an attack on person A.

3. Therefore A's claim is false.

The reason why an Ad Hominem (of any kind) is a fallacy is that the character, circumstances, or actions of a person do not (in most cases) have a bearing on the truth or falsity of the claim being made (or the quality of the argument being made).

Example of Ad Hominem

1. Bill: "I believe that abortion is morally wrong." Dave: "Of course you would say that, you're a priest." Bill: "What about the arguments I gave to support my position?" Dave: "Those don't count. Like I said, you're a priest, so you have to say that abortion is wrong. Further, you are just a lackey to the Pope, so I can't believe what you say."

An Appeal to Emotion is a fallacy with the following structure:

1. Favorable emotions are associated with X.2. Therefore, X is true.

This fallacy is committed when someone manipulates peoples' emotions in order to get them to accept a claim as being true. More formally, this sort of "reasoning" involves the substitution of various means of producing strong emotions in place of evidence for a claim. If the favorable emotions associated with X influence the person to accept X as true because they "feel good about X," then he has fallen prey to the fallacy.

This sort of "reasoning" is very common in politics and it serves as the basis for a large portion of modern advertising. Most political speeches are aimed at generating feelings in people so that these feelings will get them to vote or act a certain way. in the case of advertising, the commercials are aimed at evoking emotions that will influence people to buy certain products. In most cases, such speeches and commercials are notoriously free of real evidence.

This sort of "reasoning" is quite evidently fallacious. It is fallacious because using various tactics to incite emotions in people does not serve as evidence for a claim. For example, if a person were able to inspire in a person an incredible hatred of the claim that 1+1 = 2 and then inspired the person to love the claim that 1+1 = 3, it would hardly follow that the claim that 1+1 = 3 would be adequately supported.

It should be noted that in many cases it is not particularly obvious that the person committing the fallacy is attempting to support a claim. In many cases, the user of the fallacy will appear to be attempting to move people to take an action, such as buying a product or fighting in a war. However, it is possible to determine what sort of claim the person is actually attempting to support. In such cases one needs to ask "what sort of claim is this person attempting to get people to accept and act on?" Determining this claim (or claims) might take some work. However, in many cases it will be quite evident. For example, if a political leader is attempting to convince her followers to participate in certain acts of violence by the use of a hate speech, then her claim would be "you should participate in these acts of violence." In this case, the "evidence" would be the hatred evoked in the followers. This hatred would serve to make them favorable inclined towards the claim that they should engage in the acts of violence. As another example, a beer commercial might show happy, scantily clad men and women prancing about a beach, guzzling beer. In this case the claim would be "you should buy this beer." The "evidence" would be the excitement evoked by seeing the beautiful people guzzling the beer.

This fallacy is actually an extremely effective persuasive device. As many people have argued, peoples' emotions often carry much more force than their reason. Logical argumentation is often difficult and time consuming and it rarely has the power to spurn people to action. It is the power of this fallacy that explains its great popularity and wide usage. However, it is still a fallacy.

As a final point, in many cases it will be difficult to distinguish an Appeal to Emotion from some other fallacies and in many cases multiple fallacies may be committed. For example, many Ad Hominems will be very similar to Appeals to Emotion and, in some cases, both fallacies will be committed. As an example, a leader might attempt to invoke hatred of a person to inspire his followers to accept that they should reject her claims. The same attack could function as an Appeal to Emotion and a Personal Attack. In the first case, the attack would be aimed at making the followers feel very favorable about rejecting her claims. In the second case, the attack would be aimed at making the followers reject the person's claims because of some perceived (or imagined) defect in her character.

This fallacy is related to the Appeal to Popularity fallacy. Despite the differences between these two fallacies, they are both united by the fact that they involve appeals to emotions. In both cases the fallacies aim at getting people to accept claims based on how they or others feel about the claims and not based on evidence for the claims.

Another way to look at these two fallacies is as follows

Appeal to Popularity1. Most people approve of X.

2. So, I should approve of X, too.

3. Since I approve of X, X must be true.

Appeal to Emotion1. I approve of X.2. Therefore, X is true.

On this view, in an Appeal to Popularity the claim is accepted because most people approve of the claim. In the case of an Appeal to Emotion the claim is accepted because the individual approves of the claim because of the emotion of approval he feels in regards to the claim.

Examples of Appeal to Emotion

1. The new PowerTangerine computer gives you the power you need. If you buy one, people will envy your power. They will look up to you and wish they were just like you. You will know the true joy of power. TangerinePower.

2. The new UltraSkinny diet will make you feel great. No longer be troubled by your weight. Enjoy the admiring stares of the opposite sex. Revel in your new freedom from fat. You will know true happiness if you try our diet!

3. Bill goes to hear a politician speak. The politician tells the crowd about the evils of the government and the need to throw out the peoople who are currently in office. After hearing the speach, Bill is full of hatred for the current politicians. Because of this, he feels good about getting rid of the old politicians and accepts that it is the right thing to do because of how he feels.

The fallacy of Division is committed when a person infers that what is true of a whole must also be true of its constituents and justification for that inference is not provided.

There are two main variants of the general fallacy of Division:

The first type of fallacy of Division is committed when 1) a person reasons that what is true of the whole must also be true of the parts and 2) the person fails to justify that inference with the required degree of evidence. More formally, the "reasoning" follows this sort of pattern:

1. The whole, X, has properties A, B, C, etc.2. Therefore the parts of X have properties A, B, C, etc.

That this line of reasoning is fallacious is made clear by the following case: 4 is an even number. 1 and 3 are parts of 4. Therefore 1 and 3 are even.

It should be noted that it is not always fallacious to draw a conclusion about the parts of a whole based on the properties of the whole. As long as adequate evidence is provided in the argument, the the reasoning can be acceptable. For example, the human body is made out of matter and it is reasonable to infer from this that the parts that make up the human body are also made out of matter. This is because there is no reason to believe that the body is made up of non-material parts that somehow form matter when they get together.

The second version of the fallacy of division is committed when a person 1) draws a conclusion about the properties of indvidual members of a class or group based on the collective properties of the class or group and 2) there is not enough justification for the conclusion. More formally, the line of "reasoning" is as follows:

1. As a collective, Group or class X has properties A, B, C, etc.

2. Therefore the individual members of group or class X have properties A, B, C, etc.

That this sort of reasoning is fallacious can be easily shown by the following: It is true that athletes, taken as a group, are football players, track runners, swimmers, tennis players, long jumpers, pole vaulters and such. But it would be fallacious to infer that each individual athlets is a football player, a track runner, a swimmer, a tennis player, a swimmer, etc.

Examples of Division

1. "The ball is blue, therefore the atoms that make it up are also blue."2. "A living cell is organic material, so the chemicals making up the cell must also be organic material."

3. "Bill lives in a large building, so his apartment must be large."

4. "Sodium chloride (table salt) may be safely eaten. Therefore its constituent elements, sodium and chloride, may be safely eaten."

5. "Americans use much more electricity than Africans do. So Bill, who lives in primitive cabin in Maine, uses more electricity than Nelson, who lives in a modern house in South Africa. "

6. "Men receive more higher education than women. Therefore Dr. Jane Smart has less higher education than Mr. Bill Buffoon. "

7. "Minorities get paid less than 'whites' in America. Therefore, the black CEO of a multi-billion dollar company gets paid less than the white janitor who cleans his office."

The Argumentum Ad Ignorantiam is where one assumes a thing is true if it cannot be proven to be false or that a thing is false if it cannot proven to be true. In both directions a fallacy has occurred because in the absence of evidence no conclusion can be drawn.

argumentum ad ignorantiam ("arguing from ignorance") -- A fallacy that occurs when someone argues that because we don't know something is true, it must be false, or because we lack proof that a statement is false, it must be true. Ignorance or lack of evidence doesn't necessarily mean a position or claim is true or false. Common Examples: "No one has ever proven that UFOs exist. Therefore, they don't exist." (Something can exist despite the absence of confirmation. Lack of proof is justification for caution or even scepticism, but not dogmatic assertions.) "There is simply no proof that God exists. Therefore, God doesn't exist." (God might exist even though there is no way empirically to prove it.)

equivocation -- Sometimes referred to as "amphiboly". A fallacy that stems from the ambiguous meaning of certain words. For example, 1. Only man is logical. 2. No woman is a man. 3. Therefore, no woman is logical. "Man" in the first sentence really means "mankind," "humankind," "homo sapiens". "Man" in the second sentence means "maleness". The syllogism appears to be valid, but in fact is fallacious because of the subtle shift in meaning. 

Complex question. A complex question is a question that implicitly assumes something to be true by its construction, such as "Have you stopped beating your wife?" A question like this is fallacious only if the thing presumed true (in this case, that you beat your wife) has not been established.

Complex questions usually appear in cross-examination or points of information when the questioner wants the questionee to inadvertently admit something that she might not admit if asked directly. For instance, one might

say, "Inasmuch as the majority of black Americans live in poverty, do you really think that self-help within the black community is sufficient to address their problems?" Of course, the introductory clause about the majority of black Americans living in poverty may not be true (in fact, it is false), but an unwary debater might not think quickly enough to notice that the stowaway statement is questionable. This is a sneaky tactic, but debate is sometimes a sneaky business.

Complex Question FallacyThe complex question fallacy is committed when a question is asked (a) that rests on a questionable assumption, and (b) to which all answers appear to endorse that assumption.

Examples“Have you stopped beating your wife?”This is a complex question because it presupposes that you used to beat your wife, a presupposition that either answer to the question appears to endorse.“Are you going to admit that you’re wrong?”Answering yes to this question is an admission of guilt. Answering no to the question implies that the accused accepts that he is in the wrong, but will not admit it. No room is left to protest one’s innocence. This is therefore a complex question, and a subtle false dilemma.

Fallacy of CompositionThe fallacy of composition is the fallacy of inferring from the fact that every part of a whole has a given property that the whole also has that property. This pattern of argument is the reverse of that of the fallacy of division. It is not always fallacious, but we must be cautious in making inferences of this form.ExamplesA clear case of the fallacy of composition is this:(1) Every song on the album lasts less than an hour.Therefore:(2) The album lasts less than an hour.

Fallacy of DivisionThe fallacy of division is the reverse of the fallacy of composition. It is committed by inferences from the fact that a whole has a property to the conclusion that a part of the whole also has that property. Like the fallacy of composition, this is only a fallacy for some properties; for others, it is a legitimate form of inference.

ExampleAn example of an inference that certainly does commit the fallacy of division is this:(1) Water is liquid.Therefore:(2) H2O molecules are liquid.

The informal fallacy of accident (also called destroying the exception or a dicto simpliciter ad dictum secundum quid) is a deductively valid but unsound argument occurring in statistical syllogisms (an argument based on a generalization) when an exception to a rule of thumb [1]  is ignored. It is one of the thirteen fallacies originally identified byAristotle. The fallacy occurs when one attempts to apply a general rule to an irrelevant situation.

For example:

Cutting people with knives is a crime. →

Surgeons cut people with knives. →

Surgeons are criminals.

Accident: the fallacy of applying a general rule to a particular case whose special circumstances render the rule inapplicable.

A. The fallacy of accident results from using a statement which has a qualified meaning as if it had no qualification whatsoever.

1. E.g., "Thou shalt not kill;  therefore, you should not try to control termites in your home or fight for your country."

2. E.g., "All persons are created equal, so since you made a C in this class, you haven't been working as hard as you should."Even though people are supposedly created equal politically, it does not follow that they are created equal in academic pursuits."

B. The fallacy of accident arises from believing the general premiss which has a qualified meaning applies in all circumstances without restriction.

1. "The U.S. is a true democracy; therefore, children and criminals should be allowed to vote."

2. "People are defined as rational animals.  Therefore, you should spend more time reasoning and thinking rather than enjoying yourself with what you do."

Amphiboly

A fallacy that relies on an ambiguous word or grammatical structure to confuse or mislead an audience. This is an error due to taking a grammatically ambiguous phrase in two different ways during the reasoning. Fallacy of Amphiboly involves the use of sentences which can be interpreted in multiple ways with equal justification due to some defect in the grammar, sentence structure, and/or punctuation.

Example:

In a cartoon, two elephants are driving their car down the road in India. They say, “We’d better not get out here,” as they pass a sign saying:ELEPHANTSPLEASE STAY IN YOUR CAR

Upon one interpretation of the grammar, the pronoun “YOUR” refers to the elephants in the car, but on another it refers to those humans who are driving cars in the vicinity. Unlike equivocation, which is due to multiple meanings of a phrase, amphiboly is due to syntactic ambiguity, ambiguity caused by multiple ways of understanding the grammar of the phrase.

An amphiboly fallacy is an error in logic or fallacy that arises from ambiguity or misunderstanding due to grammar, usually through poor punctuation or word choice. This can be a fallacy that is utilized on purpose, or it can happen accidentally as a result of language used hastily or without editing. The nature of this type of fallacy is ambiguity, which means that the argument supported by such a fallacy can easily be argued against by addressing the different possible meanings. An amphiboly fallacy can also be used to great comedic effect, as the phrase plays on the ambiguity for comedic purposes.

For example, if someone said “The doctor wanted to operate on the patient, but he was not ready,” the “he” is ambiguous and could refer to either the doctor or the patient.

The anthropologists went to a remote area and took photographs of some native women, but they weren't developed.

In this example, the pronoun "they" is ambiguous between the photographs and the native women, though presumably it was intended to refer to the former.

 Converse Accident: (hasty generalization) the fallacy of considering certain exceptional cases and generalizing to a rule that fits them alone. Note that the fallacy of converse accident is the opposite of accident.

If we reason by paying too much attention to exceptions to the rule, and generalize on the exceptions, our reasoning contains this fallacy. This fallacy is the converse of the accident fallacy. It is a kind of Hasty Generalization, by generalizing too quickly from a peculiar case.

Example:

I’ve heard that turtles live longer than tarantulas, but the one turtle I bought lived only two days. I bought it at Dowden’s Pet Store. So, I think that turtles bought from pet stores do not live longer than tarantulas.

The original generalization is “Turtles live longer than tarantulas.” There are exceptions, such as the turtle bought from the pet store. Rather than seeing this for what it is, namely an exception, the reasoner places too much trust in this exception and generalizes on it to produce the faulty generalization that turtles bought from pet stores do not live longer than tarantulas.

The fallacy of converse accident (also called reverse accident, destroying the exception, or a dicto secundum quid ad dictum simpliciter) is an informal fallacy that can occur in a statistical syllogism when an exception to a generalization is wrongly excluded, and the generalization wrongly called for as applying to all cases.

For example:

If we allow people with glaucoma to use medical marijuana, then everyone should be allowed to use marijuana.

False Cause

Improperly concluding that one thing is a cause of another. The Fallacy of Non Causa Pro Causa is another name for this fallacy. Its four principal kinds are the Post Hoc Fallacy, the Fallacy of Cum Hoc, Ergo Propter Hoc, the Regression Fallacy, and the Fallacy of Reversing Causation.

  False Cause:  the fallacy committed when an argument mistakenly attempt to establish a causal connection.  There are two basic interrelated kinds.

Example:

My psychic adviser says to expect bad things when Mars is aligned with Jupiter. Tomorrow Mars will be aligned with Jupiter. So, if a dog were to bite me tomorrow, it would be because of the alignment of Mars with Jupiter.

Ignoratio elenchi / Irrelevant conclusion

The fallacy of Irrelevant Conclusion consists of claiming that an argument supports a particular conclusion when it is actually logically nothing to do with that conclusion.

For example, a Christian may begin by saying that he will argue that the teachings of Christianity are undoubtedly true. If he then argues at length that Christianity is of great help to many people, no matter how well he argues he will not have shown that Christian teachings are true.

Sadly, these kinds of irrelevant arguments are often successful, because they make people to view the supposed conclusion in a more favorable light.

Irrelevant Conclusion: The conclusion that is drawn is irrelevant to the premises; it misses the point.

Example:

In court, Thompson testifies that the defendant is a honorable person, who wouldn’t harm a flea. The defense attorney uses the fallacy by rising to say that Thompson’s testimony shows once again that his client was not near the murder scene.

The testimony of Thompson may be relevant to a request for leniency, but it is irrelevant to any claim about the defendant not being near the murder scene. Other examples of this fallacy are Ad Hominem,Appeal to Authority, Appeal to Emotions, and Argument from Ignorance.

Accent FallaciesAccent fallacies are fallacies that depend on where the stress is placed in a word or sentence. The meaning of a set of words may be dramatically changed by the way they are spoken, without changing any of the words themselves. Accent fallacies are a type of equivocation.A fallacy of accent occurs when a statement creates unnecessary ambiguity because of a shift of emphasis either in spoken or written words. 

Accent

The accent fallacy is a fallacy of ambiguity due to the different ways a word is emphasized or accented.

Example:

A member of Congress is asked by a reporter if she is in favor of the President’s new missile defense system, and she responds, “I’m in favor of a missile defense system that effectively defends America.”

With an emphasis on the word “favor,” her response is likely to favor the President’s missile defense system. With an emphasis, instead, on the words “effectively defends,” her remark is likely to be against the President’s missile defense system. And by using neither emphasis, she can later claim that her response was on either side of the issue. Aristotle’s version of the fallacy of accent allowed only a shift in which syllable is accented within a word.

Appeal to Ignorance

The fallacy of appeal to ignorance comes in two forms: (1) Not knowing that a certain statement is true is taken to be a proof that it is false. (2) Not knowing that a statement is false is taken to be a proof that it is true. The

fallacy occurs in cases where absence of evidence is not good enough evidence of absence. The fallacy uses an unjustified attempt to shift the burden of proof. The fallacy is also called “Argument from Ignorance.”

Example:

Nobody has ever proved to me there’s a God, so I know there is no God.

This kind of reasoning is generally fallacious. It would be proper reasoning only if the proof attempts were quite thorough, and it were the case that if God did exist, then there would be a discoverable proof of this. Another common example of the fallacy involves ignorance of a future event: People have been complaining about the danger of Xs ever since they were invented, but there’s never been any big problem with them, so there’s nothing to worry about.