Fallacies of Ambiguity

These fallacies, also called fallacies of clearness, occur in arguments whose formulations contain ambiguous words or phrases, whose meanings shift and change more or less subtly in the course of the argument and thus render it fallacious.

Equivocation - a fallacy committed when the conclusion of the argument depends on the fact that one or more words are used, either explicitly or implicitly, in two different senses in the argument.

A law can be repealed by legislative authority. The law of gravity is a law. Therefore, the law of gravity can be repealed by the legislative authority.

To identify the fallacy of equivocation, look for reasoning that involves a shift between two or more sense of a key word or phrase in the argument.

Amphiboly – this fallacy occurs when the arguer misinterprets a statement that is ambiguous owing to some structural defect and proceeds to draw a conclusion based on this faulty interpretation.

John told Bob that he had made a mistake. It follows that John has at least the courage to admit his own mistakes

Professor Johnson said that he will give a lecture about heart failure in the biology lecture hall. It must be the case that a number of heart failures have occurred there recently.

Amphiboly differs from equivocation in two important ways: 1) the former involves a structural defect in a statement while the latter is always traced to an ambiguity in the meaning of one or more words; 2) the former involves a mistake made by the arguer in interpreting an ambiguous statement made by someone else, whereas in the latter the ambiguity is typically the arguer’s own creation.

Composition – a fallacy committed when the conclusion of an argument depends on the enormous transference of a characteristic from the parts of something onto the whole. In other words, the fallacy occurs when it is argued that because the parts have a certain characteristic, it follows that the whole has the characteristic, too, and the situation is such that the characteristic in question cannot be legitimately transferred from the parts to the whole.

It is sometimes called the part/whole fallacy because the arguer mistakenly concludes that the whole must have some characteristics because each part or member has that characteristic. The structure of this fallacy is: each member of W is f. Therefore, W is f. The assumption of the argument is that what is true of the part is true of the whole. This is often false especially in those cases which the whole is more than the sum of its parts.

A feather is light. Therefore, a plastic containing a billion feathers is light.

Each member of the orchestra is excellent, so the orchestra is excellent.

Each player on this basketball team is an excellent athlete. Therefore, the team as a whole is excellent.

To recognize the fallacy of composition, look for an argument that moves from a claim about the parts or members of a group to a conclusion about the whole. Consider then whether it is justifiable to attribute what is true of the parts to the whole.

Division – a fallacy that is the exact reverse of composition. As composition goes from parts to whole, division goes from whole to parts. The fallacy is committed when the conclusion of an argument depends on the erroneous transference of a characteristic from a whole onto parts. Its structure is: W is f. Therefore, each member of W is f.

Salt is a nonpoisonous compound. Therefore, its component elements, sodium and chlorine, are non poisonous.

he union voted to strike. Therefore, every member of the union voted to strike.

Humans are the only animals capable of philosophical thinking. Thus every person is capable of philosophical thinking.

To recognize the fallacy of division, look for an argument that moves from a claim about a whole group or a group to a conclusion about one or all of the members of the whole. Then consider whether it is justifiable to attribute what is true of the whole to its parts.

Accent – a fallacy that arises from the mistaken interpretation of a statement but the mistake is due to the ambiguity in the way the statement is spoken. It occurs when the arguer illegitimately stresses one or more words in the given statement and then proceeds to draw a conclusion based on the resultant interpretation.

Catherine said (she) did not (drive) (her) (car) (today). Therefore: 1. Somebody else must have driven it; 2. She may have washed it; 3. She must have driven someone else’s; 4. She must have driven her truck; 5. She must have driven it yesterday.

A variation of the fallacy of accent occurs when the person who makes the original statement entices the arguer into a certain misinterpretation and thereby tricks him into construction a fallacious argument.

[The chief mate did not drink yesterday] [The captain is sober today.]

Fallacies of Relevance

Informal Fallacies are typical errors or mistakes that arise commonly in ordinary discourse. They use persuasive arguments and so, although invalid, may appeal or come across as correct. They are then to be treated with caution in order to avoid the traps they set. We may technically define a fallacy as a type of an argument that may seem to be correct but proves, on examination, not to be so.

Fallacies of Relevance

When an argument relies on premises that are not relevant to its conclusion and therefore cannot be establish its truth. The connection between the premises and the conclusion is often emotional. In a good argument, it must be noted; the premises must provide genuine evidence for the conclusion.

Argumentum ad baculum – appeal to force – the use of threat in a form calculated to win the assent of another person or cause him to accept a conclusion. It is the discourse of power. The threat may either be physical or psychological so it is an argument based upon a threat. Arguers using this type of appeal try to persuade you by pointing out their powers over you or by warning you of the bad consequences of refusing to accept their argument.

Ladies and gentlemen of the jury, if you do not bring in a verdict of guilty, you may be this killer’s next victim!

We cannot have this statement on expenditures coming to the attention of the president. You have been the accountant here for nearly twenty years. It would be a shame to ruin all that now. I think it would be wise of you to take another look at the books.

To recognize the fallacy of appeal to force, look for the presence of a threat that is either explicit or subtly disguised.

Argumentum ad misericordiam – appeal to pity – when careful reasoning is replaced by devices contrived to cause sympathy or to evoke pity from another to get the other accept the conclusion. The basic structure of the argument is this: you should accept my conclusion out of pity. The arguer urges you to believe something by arousing your sympathy for him or his cause.

There is no question that what this young man did is intolerable and repugnant. He admits it himself. But you are not here to evaluate this man’s conduct morally; you are here to try him and determine his guilt or innocence. And as you think this over, I want you to think hard about this young man, his home life and his future, which you now hold in your hands. Think about his broken home, never knowing his father, being left by his mother. Think about the poverty he has known, the foster homes, the birthdays going unnoticed, and the Christmas he has never had. And think hard about what life in prison will do to him. Think about these things, and I know you will acquit him of this crime.

To recognize the fallacy of appeal to pity, look for premises that appeal to your sympathy.

Argumentum ad populum – appeal to the people or appeal to the emotion – careful reasoning is placed with devices aimed at creating enthusiasm and emotional support.

The basis structure of the argument is this: some statement S is true because most people believe S. It is, in effect, an appeal to commonly or traditionally held beliefs. The main error of this argument lies in the act that the popular acceptance of a policy does not show it to be wise. The fact that a great many people hold it to be true does not prove an opinion to be true.

To legalize jueteng or any other form of gambling because many people are engaging in it anyway.

To say that the constitution is defective because many people want it to be amended.

Direct: to excite the emotion and enthusiasm of the crowd. To arouse a kind of mob mentality. Not limited to verbal argumentation but also employs emotional charged phraseology.

political campaigns. slogans and labels.

Indirect: the appeal is addressed to one or more individuals separately. There is the bandwagon; the vanity – associating a product with a certain celebrity who is admired and pursued, the idea being that you, too, will be admired and pursued if you use it; and the snobbery type.

BANDWAGON:

90% are using Zest. You will be left behind or left out of the group if you do not use the product.

VANITY:

Only the ultimate in fashion could compliment the face of Cindy Crawford. Spectrum sunglasses – for the beautiful people in the jet set.S

SNOBBERY:

A Jaguar is not for everyone. If you think you belong to the select few, this distinguished classic may be seen and test driven at Ortigas Motor Cars. By appointment only, please!

To recognize the fallacy of appeal to the people, look for an argument in which the conclusion is based on assertions about commonly or traditionally held beliefs. The observation of Bertrand Russel is worth noting: In view of the silliness of the majority of mankind, a widespread belief is more likely to be foolish than sensible.

Argumentum ad hominem – attack against the person – when an attack is leveled not at the claim or conclusion of an opponent but at the person of the opponent. It is an attack upon the person rather than the persons’ ideas, on the opponent’s character implying that what he says should not be believed because of his character flaw. There are three common types of ad hominem arguments:

Abusive: when the attack is directly against a person seeking to defame or discredit him. It involves two claims: first, that the opponent possess a ceratin undesirable or negative characteristic and secondly, that the opponents’ words or abilities are not to be trusted because of that characteristic. The structure of this fallacy is: whatever anyone with undesirable characteristic X says is probably not true. Person A has undesirable characteristic X. Therefore, whatever A says is probably not true.

Well now, you have all heard Professor Clark tell us about the theory of evolution. But I am not surprised that he neglected to tell you that he is a godless atheist! How can this man speak the truth, I ask you?

To identify the ad hominem abusive fallacy, look for an attack on the person’s character rather than a person’s statements.

Circumstantial – when the attack is indirectly against persons suggesting that they adopt their view chiefly because of their special circumstances or interests. It implies that the opponent has special, usually self-interested, reasons for his or her claims. The argument attempts to refute the person’s statements not by offering reasons against it but by suggesting that the person himself does not have good reasons or honest motives for the position. The structure of this fallacy may be presented as follows: Person A has self-interested reasons for asserting S. Therefore, S is probably not true.

The auto industry lobbyists have been arguing that tax reform is unnecessary. But just remember this: it is the auto industry that stands to benefit the most if there is no change in the current tax laws.

To identify the ad hominem circumstantial fallacy, look for an argument that claims that the opponent advances his or her argument not because it is true but because the opponent has some other, usually ulterior, motive for wanting his or her argument accepted.

Tu quoque – Shifting the burden of guilt. It is an argument in which one defends oneself by accusing one’s attacker, usually of a similar wrongdoing. “Two wrongs do not make a right” so that even if the arguer is right in attacking his accuser, he has not defended himself against the charge.

Yes, I admit, I did lie to you about last night. But you have lied to me also before.

To identify the tu quoque fallacy, look for an argument that attempts to offer a defense by accusing the accuser of a similar wrongdoing.

The character of an individual is logically irrelevant to the truth or falsehood of what the person says. Abusive premises may persuade by the psychological process of transference. The field of emotional disapproval, when it is evoked, may be extended so as to include disagreement with the assertion the person makes. The same is to be said about assigning guilt by association. The circumstances of one who makes or rejects some claim have no bearing on the truth of that claim.

Argumentum ad verecundiam – appeal to authority – when the premises of an argument appeal to some party having no legitimate claim to authority in the matter at hand. This means, in other words, that the fallacy of appeal to authority occurs when the authority cited is not qualified in the relevant matters or, less typically, is not free from adverse influences. The argument in this case relies upon the assertions of someone who is not truly in a position to know.

According to my physics professor, Emily Dickinson’s poetry is for the birds.

That is good enough for me.

Marvis Frazier is America’s greatest boxer. I have that on the authority of Marvis’ father, Joe Frazier.

The underlying idea of such arguments is that some statement S is true because some authority A has said it is true. The argument’s basis structure is thus – authority A asserts that S. Therefore, S. Immediately this argument can be seen to be neither valid nor strong, since the mere fact that someone asserts S neither makes it so nor makes it probable. Typically, however, the arguer believes more than the mere fact that A asserts S. The arguer very likely is assuming such things as that A is someone who knows what he is talking about regarding S, or that A is speaking without basis , or that A is telling the truth. If those similar assumptions are well founded, the appeal to authority A may constitute good reasoning. Not all appeals to authority are fallacious. After all, we should accept the testimony of qualified and unbiased experts for we cannot be experts in every field ourselves.

To recognize the appeal to authority, look for an argument based primarily on the premise that some person or some publication reports that S is true. The fallacy occurs when the person or publication is not relevantly qualified or is not speaking without bias; in other words, whenever the truth of some proposition is assented on the basis of the authority of one who has no special competence in that sphere, the appeal to misplaced authority is committed.

Argumentum ad ignorantiam - appeal to ignorance – when it is argued that a position is true on the ground that it has not been proved false or vice-versa. The premises tell us that nothing can be known with certainty one way or the other about a certain subject while the conclusion states something definite. The two structures of the appeal to ignorance are: We do not know that S is false. Therefore, S is true or We do not know that S is true. Therefore S is false.

Well, I have examined all the arguments for the existence of God, and I have seen that none of them proves that God exists. That is reason enough for me: there is no God!

The lack of evidence that S is true (or not true) should not, in most cases, be taken as proof that S is not true (or true). However, there are at least two kinds of cases that resemble the appeal to ignorance in which a lack of evidence may justify the conclusion that S is true (or not true). In a court of law the failure to establish that a person has committed a crime is considered sufficient to allow us to conclude that the person is guilty. Thus, lawyers may argue that their clients are innocent because there is no evidence of their guilt. Notice, however, that finding a person innocent or guilty in a court of law is not a determination that the person did not commit the crime; it is a determination that the evidence does not justify a judgment of guilt. But if we conclude that a defendant did not commit the crime because he was found not guilty, we would be committing the fallacy of appeal to ignorance. Similarly, in scientific reasoning a failure to disconfirm or disprove a hypothesis lends support to the hypothesis, although it does not usually justify concluding that the hypothesis is true. Rather, each failure to disconfirm the hypothesis indicates that it is more probable.

Our ignorance to prove either the truth or falsity of a conclusion primarily signifies our inability and not the truth or falsity of the very conclusion. The fallacy of appeal to ignorance occurs when the lack of evidence or proof is not relevant to the conclusion but the arguer believes that it is.

To recognize the fallacy of appeal to ignorance, look for a conclusion based upon are absence of proof or evidence.

Accident – committed when a general rule is applied wrongly to a specific case. The general rule is cited in the premises and then wrongly applied to the specific case mentioned in the conclusion. Because of the accidental features of the specific case, the general rule does not fit.

Freedom of speech is a constitutionally guaranteed right,. Therefore, that radical communist should not be arrested for his speech that incited that riot last week.

Property should be returned to its rightful owner. That drunken marine soldier who is having a fight lent you his gun and he wants it back now. Therefore, you should return it to him now.

Converse Accident – hasty generalization – committed when a conclusion is drawn about all the members of a group from evidence that pertains to selected sample. The fallacy occurs when there is likelihood that the sample is not representative of the group. Such likelihood may arise if the sample is either too small or not randomly selected.

I have spoken to the members of the campus Siglakas club, and they prefer to use the activity fund for a film series on birds. So probably a majority of the two thousand students would prefer a film series on birds.

To identify the fallacy of hasty generalization, look for a conclusion that generalizes over a group. Notice whether the basis for the generalization is both representative of the group and sufficiently large to justify the generalization.

False Cause – committed whenever the link between premises and conclusion depends on some imagined causal connection that does not in fact exist. Any reasoning that relies on treating as the cause of a thing what is not really its cause is a fallacy – non causa pro causa. The most common variety of false cause is the error of concluding that an event is cause by another simply because it follows the other – post hoc ergo propter hoc.

A black cat crossed my path and later I tripped and sprained my ankle. It must be that black cats are really bad luck

During the past two months, every time that the cheerleaders wore blue ribbons in their hair, the basketball team was defeated. Therefore, to prevent defeats in the future, the cheerleaders should get rid of those blue ribbons.

There are more laws in the books today than ever before, and more crimes are being committed than ever before. Therefore, to reduce crime we must eliminate the law.

Another type of fallacy of false cause is called oversimplification. This occurs when an arguer explains the occurrence of some event or phenomenon in terms of one or more of its least important causes.

I blame the television media for the epidemic of hijackings, kidnappings, and other acts of terrorism. If we would stop televising terrorist acts, they would stop.

To identify the fallacy of false cause, look for the claim that one thing or event is cause by or explained as the result of some other thing or event A. Then consider whether there is any good evidence that A causes B. The variation called oversimplification can usually be spotted when an arguer proposes a solution to a problem while at the same time overlooking other causal factors.

Petitio principii – begging the question – assumes the truth of what one seeks to prove, in the effort to prove it. Phrasing the argument so that the premise and conclusion say the same thing in two slightly different ways. Another name for this is circular argument. The argument begs the question at issue because it asks that the statement to be proved be granted beforehand. It assumes as true the very point in question.

Philosophers are highly intelligent individuals because if they were not highly intelligent they would not be philosophers.

The Bible asserts that God exists. The Bible is the divine word of God. Therefore, God exists.

It is plain to see that suicide is morally wrong because, as any thinking person will admit, no one is ever justified in taking his or her own life.

To recognize the fallacy of begging the question, look for an argument that assumes already the very issue under debate. Be aware that a question-begging argument may appear to offer legitimate, independent support, but on closer examination a premise in fact either itself rests upon the conclusion or restates the conclusion in different words.

Complex question – when a single question that is really two or more questions is asked and the single answer is then applied to both questions.

Have you stopped cheating on your girlfriend?

If respondents are not sophisticated enough to identify a complex question when one is put to them, they may answer quite innocently and be trapped by a conclusion that is supported by no evidence at all.

False analogy – a fallacy committed when the analogy is not strong enough to support the conclusion that is drawn. It draws a conclusion about something on the basis of an analogy with or resemblance to some other thing. The assumption is that if two or more things are alike in some respects, they are alike in some other respect. The structure of the argument is as follows: A and B are both f, g, and H. A is also j. Therefore, probably B is j.

Harper’s new car is bright blue, has leather upholstery, and gets an excellent mileage. Crowley’s new car is also bright blue and has leather upholstery. Therefore, it probably gets excellent mileage too.

To recognize the fallacy of the false analogy, look for an argument that draws a conclusion about one thing, event, or practice on the basis of its analogy or resemblance to other. The fallacy occurs when the analogy or resemblance is not sufficient to warrant the conclusion, as when, for example, the resemblance is not relevant to the possession of the inferred feature or there are relevant dissimilarities.

Slippery slope – this a variety of the false cause fallacy. It occurs when the conclusion of an argument rests upon the claim that a certain event will set off a chain reaction, leading in the end to some undesirable consequence, yet there is no sufficient reason to think that the chain reaction will actually take place.

Attempts to outlaw pornography threaten basic civil rights and should be summarily abandoned. If pornography is outlawed, censorship of news papers and news magazines is only a short step away. After that there will be censorship of textbooks, political speeches, and the content of lectures delivered by university professors. Complete mind control by the central government will be the inevitable result.

You have all heard of grade inflation. Well, I want to speak to you about grade depression: the serious harm we do to students by grading them too hard rather than too easily. What does it do to students to measure them by too strict a standard? It frustrates them. It conditions them to expect failure. They recoil from responsibility, always taking the easy route rather than learning to challenge and hence improve themselves. They develop habits of dependency, and many develop the symptoms of neurosis and other psychological disorders. Can we afford a generation of weak, dependent people unsuited for the demands of contemporary society?

To recognize the slippery slope fallacy, look for an argument claiming that a certain practice or event will initiate a series of events ultimately leading to some undesirable consequences.

Red herring – a fallacy that is committed when the arguer diverts the attention of the reader or listener by addressing a number of extraneous issues and ends by presuming that some conclusion has been established. The fallacy got its name from the practice of using a herring, a particularly smelly fish when cooked, to divert hunting dogs from the scent of a fox. To commit the fallacy of red herring in an argument is to draw attention away from an issue by raising some other, seemingly related issue. In so doing, the arguer attempts to sidetrack the opponent’s argument.

Friends and neighbors I urge you to defeat the proposal to make jail sentences mandatory for drunk drivers. My opponent claims that it will reduce the number of accidents caused by drunk drivers. But if we really want to reduce traffic accidents, then we should stand behind those men and women whose chief responsibility is our safety. I am referring of course, to our valiant police officers, what we need to is increase their salaries, beef up the police force, and, most importantly, stop butting into their business with troublesome people.

I agree with my opponent that pornography is a national problem, and I am almost persuaded by his argument that women are being degraded and victimized by pornography. I say, almost persuaded… until I remember the facts that my opponent obviously overlooks: namely, that the people of South Africa are not merely degraded and victimized, they are deprived of every right due a human being. And what I do not understand is how we convince ourselves that our so called national problem takes precedence over genuine oppression and suffering.

To recognize the fallacy of red herring, look for an argument in which the speaker responds by directing attention away from the issue to other, seemingly related issues.

Suppressed evidence – a fallacy committed when an arguer ignores evidence that would tend to undermine the premises of an otherwise good argument, causing it to be unsound or uncogent. Suppressed is a fallacy of presumption and is closely related to begging the question. As such, its occurrence does not affect the relationship between premises and conclusion but rather the alleged truth of the premises. The fallacy consists in passing off what are at best half-truths as if they were the whole truth, thus making what is actually a defective argument appear to be good. It is especially common among arguers who have a vested interest in the situation to which the argument pertains.

The second amendment to the constitution states that the right of the people to keep and bear arms shall not be infringed. But a law controlling handguns would infringe on the right to keep and bear arms. Therefore, a law controlling hand guns would be unconstitutional.

Deduction and Induction

Arguments are traditionally divided into two different types, deductive and inductive.

A deductive argument is one in which the conclusion follows necessarily from the premises; in other words, the premises support the conclusion in such a way that if they are assumed true, it is impossible that the conclusion be false.

An inductive argument is one in which the conclusion follows only probably from the premises; in other words, the premises support the conclusion in such a way that if they are assumed true, then, based on that assumption, it is only probable that the conclusion be true.

Three factors that bear upon the evaluation of an argument is inductive or deductive are the following:

· the occurrence of special indicator words – If, in drawing a conclusion the arguer uses words such as “probable,” “improbable,” “plausible,” “implausible,” “likely,” “unlikely,” or “reasonable to conclude,” the evaluator may take such indicators as reason for considering the argument inductive.

Neon has unstable isotopes. Therefore, since argon is similar in may ways to neon, it probably follows that argon has unstable isotopes, too.

On the other hand, if the arguer uses words such as “necessarily,” “certainly,” “absolutely,” or “definitely,” the evaluator may consider the argument deductive.

If a substance is a noble gas, it is inert. Therefore, since argon is a noble gas, it necessarily follows that it is inert.

· the nature of the inferential link between premises and conclusion – If this link is such that the conclusion follows necessarily from the premises, the argument is clearly deductive. To say that the conclusion follows “necessarily” means that the premises support the conclusion in such a way that if they are assumed true, it is absolutely impossible that the conclusion be false.

All saleswomen are extroverts. Judy Wage is a saleswoman. Therefore, she is extrovert.

On the other hand, if the conclusion does not follow necessarily from the premises but does probably, it is usually best to consider the argument inductive.

The vast majority of saleswomen are extroverts. Rose Liam is a saleswoman. Therefore, Rose Liam is an extrovert.

· The character or form of argument the arguer uses – Sometimes it happens that an argument contains no indicator words and the conclusion follows neither necessarily nor probably from the premises, that is, the premises provide no clear support for the conclusion, This situation points out the need for the third factor to be taken into account, which is the character or form of argumentation the arguer uses.

Five such types of argumentation that are typically deductive are the following:

Argument based on mathematics	An argument in which the conclusion depends on some purely arithmetic or geometric computation or measurement. A shopper may place two apples and the three oranges into a paper bag and then conclude that the bag contains five fruits. /A surveyor might measure a square piece of land and, after determining that it is 100 feet on each side, conclude that it contains 10,000 square feet.
Argument from definition	An argument in which the conclusion is claimed to depend upon the definition of some word or phrase used in the premise or conclusion. Claudia is mendacious, so she tells lies. / This paragraph is prolix, so it follows that it is excessively wordy.
Categorical syllogism	A syllogism in which each statement begins with one of these quantifiers: “all,” “no,” “some.” All lasers are optical devices. Some lasers are surgical instruments. Therefore, some optical devices are surgical instruments.
Conditional syllogism	A syllogism having a conditional statement for one or both of its premises. If quartz scratches glass, then quartz is harder than glass. Quartz scratches glass. Therefore, quartz is harder than glass.
Disjunctive syllogism	A syllogism having a disjunctive statement (“either… or”) for one or both of its premises. Either breach of contract is a crime or it is not punishable by the state. Breach of contract is not a crime. Therefore, it is not punishable by the state.

The following are typically inductive forms of argumentation. Inductive arguments are such that the content of the conclusion is in some way intended to go beyond the content of the premise. The premises of such an argument typically deal with some subject that is relatively familiar, and the conclusion then moves beyond this to a subject that is less familiar or that little is known about.

Prediction	The premises deal with some known event in the present or past, and the conclusion moves beyond this event to some event in the relative future. Because certain meteorological phenomena have been observed to develop over a certain region in the Pacific, a storm will occur there in the next several hours.
Argument from analogy	An argument that depends on the existence of an analogy, or similarity, between two things or state of affairs. Because of the existence of this analogy, a certain condition that affects the better known thing or situation is concluded to affect the similar lesser known thing or situation. From knowledge that his Mercedes car is an expensive car, I argue that your car, being a Mercedes, is also expensive.
Inductive generalization	An argument that proceeds from the knowledge of selected sample to some claim about the whole group. Because the members of the sample have a certain characteristic, it is argued that all the members of the group have the same characteristic. One may argue that because three oranges selected from a certain crate were especially tasty and juicy, all the oranges from that crate are especially tasty and juicy.
Argument from authority	An argument in which the conclusion rests upon a statement made by some presumed authority or witness. A lawyer may argue that the criminal committed no murder because an eyewitness testified to that effect under oath.
Argument based on signs	An argument that proceeds from the knowledge of a certain sign to knowledge of the thing or situation that the sign symbolizes. When driving on an unfamiliar highway, one might see a sign indicating the road makes several sharp turns one mile ahead. Base on this information, one might argue that the road does indeed make several sharp turns one mile ahead.
Causal inference	An argument that proceeds from knowledge of a cause to knowledge of the effect or conversely, from knowledge of an effect to knowledge of a cause. From the knowledge of the bottle of wine had been accidentally left in the freezer overnight, someone might concluded that it had frozen (cause to effect) Or, after tasting a piece of chicken and finding it dry and crunchy, one might conclude that it had been overcooked. (effect to cause)

Although every argument involves the claim that its premises provide evidence for the truth of its conclusion, only a deductive argument involves the claim that its premises provide conclusive evidence. In the case of deductive arguments the technical terms valid and invalid are used in place of correct and incorrect. A deductive is valid when its premises, if true, do provide conclusive evidence for its conclusion, that is, when premises and conclusion are so related that it is absolutely impossible for the premises to be true unless the conclusion is true also. Every deductive argument is either valid or invalid. The task of deductive logic is to clarify the nature of the relation between premises and conclusion in valid arguments, and thus to allow us to discriminate valid and invalid arguments.

An inductive argument, on the other hand, involves the claim, not that its premises give conclusive evidence for the truth of its conclusion, but only that they provide some evidence for it. Inductive arguments are neither valid nor invalid in the sense in which those terms are applied to deductive arguments. Inductive arguments may, of course, be evaluated as better or worse, according to the degree of likelihood or probability, which their premises confer upon their conclusions.

Diagramming Arguments

Diagramming Arguments – Another way to expose an argument is to diagram it. To do this, first read through and number each statement in sequence. Then draw an arrow from the statement number of the premise to the number of the conclusion as follows.

Single support:

[1] The branch manager was promoted to company vice president; therefore,

[2] he will transfer to the main office.

1-------->2

The diagram shows that statement 1 is the only support offered for the conclusion in statement 2.

Joint support:

[1] If the branch manager is promoted to vice president of the company, then he will transfer to the main office. [2] He is bound to be promoted. [3] So, he will be transferring to the main office.

1 + 2------->3

This argument offers two premises for concluding that 3. Moreover, the premises operate together in support of the conclusion. Premise 1 does not provide reason for 3 without being joined with 2. This is called joint support and their dependence is indicated by the + sign.

Independent support:

[1] Cats make good pets because [2] they are affectionate. [3] They are clean. [4] They are entertaining and [5] they do well in apartments.

The conclusion is statement 1. Notice that four distinct premises are offered in support and that these premises do not need one another to provide support. This is called independent support.

2------------>

3------------>

1

4----------->

5----------->

Joint support should not be confused with independent support. A premise provides independent support if it does not need another premise or is not needed by another premise to support the conclusion. Otherwise it provides joint support along with another premise.

Extended argument:

[1] Cats make good pets because [2] they are affectionate. [3] They are clean. [4] They are entertaining and [5] they do well in apartments. So , [6] if you want a good pent, you should get a cat.

Premises 2 through 5 support the conclusion 1. From that conclusion it is further concluded that 6.

2------------->

3------------>

1----------> 6

4------------>

5------------>

This is called an extended argument because it contains an argument within an argument.

Cats make good pets and cats make good anatomical subjects. Therefore, some good pets make good anatomical subjects. Since good anatomical subjects are in high demand in medical schools, it follows that some good pets are in high demand in medical schools.

1+ 2--------> 3 + 4--------> 5

Above we see that premises 1 and 2 support 3. Statement 3 is then combined with 4 to support the conclusion 5

Identifying Non-arguments

One way to facilitate the recognition of arguments is to distinguish them from nonarguments. This is not easy especially when a passage contains no argument indicators. For such a passage could simply be a series of unsupported assertions rather than an argument. The following are typical kinds of nonarguments:

Warnings – discourses aimed at modifying someone’s behavior. If no evidence or reason is given to prove that someone should do something or avoid doing something then there is no argument.

Let everyone know that no mercy shall befall any violator of the law in this country.

Statements of belief or opinion – expressions of what someone happens to believe or think at a certain time. When no evidence or reason is given to prove that what the author thinks is true is no argument.

I think a nation such as ours, with its high moral traditions and commitments, has a further responsibility to know how we became drawn into this conflict, and to learn the lessons it has to teach us for the future. [Alfred Hassler, Saigon]

Description – consists of one or more statements that, taken together, cause a certain picture to appear in the mind of the reader.

At Rajghat, a few hundred feet from the river, a fresh pyre had been built of stone, brick and earth. It was eight feet square and about two feet high. Long, thin sandalwood logs sprinkled with incense were stacked on it. Mahatma Gandhi’s body was lay on the pyre with his head to the north. In that position Buddha had met his end. [Louis Fisher, Gandhi: His Life and Message for the World]

Report – a group of statements that conveys information about some situation or event.

“56,000 curies of radioactive tritium were accidentally released from the Savanna River nuclear weapons plant in South Carolina. A spokesman for the plant said that the radiation posed ‘no health hazard to the public’ since it was ‘equivalent to the amount that would be received on a 30-minute jet flight at 36,000 feet’”.

Expository passage – It often happens that an author will begin a paragraph with a topic sentence and then go on develop it. The author’s aim is not to prove the topic sentence but merely to expand or develop it.

There is a stylized relation of artist to mass audience in the sports, especially in baseball. Each player develops a style of his own – the swagger as he steps to the plate, the unique windup a pitcher has, the clean-swinging and hard-driving hits, the precision quickness and grace of infield and outfield, the sense of surplus power behind whatever is done.

The aim of this of this passage is not so much to prove that the first statement is true as it is to flesh out the notion of a stylized relation to a mass audience.

Illustration – Consists of a statement about a certain subject combined with a reference to one or more specific instances intended to exemplify that statement. Illustrations are often confused with arguments because many of them contain indicator words.

Chemical elements, as well as compounds, can be represented by molecular formulas. Thus, oxygen is represented by “O2”, sodium chloride by “NaCl”, and sulfuric acid as “H2SO4”.

Many scientists turn to music for rest and relaxation. Thus Albert Einstein played the violin.

The above passages are not arguments because there is no claim that anything follows from evidence. The purpose of the word “thus” is not to indicate that something is being proved but merely to show how something is done.

Comparison – compound statements that point out a similarity between two events or instances.

Just as normal men would die without water, so Jack would die without wine.

Conditional – an “if… then…” statement. Every conditional statement is made up of two component statements. The statement immediately following the “if” is called the antecedent and the other following the “then” is called the consequent.

Conditional statements are not arguments for the following reason: in an argument the premises are asserted to be true, and the conclusion, because it is claimed to follow from the premises, is also asserted to be true. In a conditional statement, on the other hand, neither the antecedent nor the consequent is asserted as true. What is asserted is that if the antecedent is true, then the consequent is true. But while no single conditional statement is an argument, a conditional statement may serve as either the premise or the conclusion of an argument.

If cigarette companies publish warning labels, then smokers assume the risk of smoking.

Cigarette companies do publish warning labels.

Therefore, smokers assume the risk of smoking.

Conditional statements are very important in logic because they are use to express the relationship between necessary and sufficient conditions. An event A is said to be sufficient condition for an event B whenever the occurrence of A is all that is required for the occurrence of B. A sufficient condition for increasing one’s heart rate is running 1,000 yards.

On the other hand, an event B is said to be a necessary condition for an event A whenever A cannot occur without the occurrence of B. A necessary condition for watching television is opening your eyes.

Temporal sequence – besides its logical sense, the premise indicator since has a temporal meaning which is sometimes mistakenly interpreted as an argument but is really a way of saying simply that in the period of time following an event several others subsequently happened.

Since Marilyn Monroe died, men have walked the moon.

Recommendation – Although it uses the term therefore and similar terms, a recommendation is not an argument. It does not establish a claim but only cites basis for the action prescribed.

I have no misgivings regarding the professional competence and the moral integrity of the applicant. I therefore recommend him for your favorable consideration.

Explanations – Every explanations is composed of two distinct components: the explanandum and the explanans. The former is the statement that describes the event or phenomenon to be explained, while the latter is the state or group of statements that purports to do the explaining. Explanations are sometimes mistaken for arguments because they often contain the indicator word because. Yet explanations are not arguments for the following reasons; in an explanation, the explanans is intended to show why something is the case, whereas in an argument the premise are intended to prove that something is the case

The Challenger spacecraft exploded after liftoff because an O-ring failed in one of the booster rockets.

The sky appears blue from the earth’s surface because light rays from the sun are scattered by particles in the atmosphere.

Cows can digest grass, human cannot, because their digestive systems contain enzymes not found in humans.

There a number of clues to help whether an argument or an explanation is being offered.

1.) The conclusion of an argument is generally something regarded by the arguers in need of support while the premises are regarded as already will known. In an explanation, on the other hand, the fact being explained is generally regarded as already well established, while the explanatory factors cited are often highly speculative.


2.) When because or similar terms are used an explanation indicators, they can be replaced without change of senses with as a result of or due to.


3.) When modified by adverbs like definitely, probably, and possibly or by conjunctions like “either-or” or “not-but” because can only be interpreted as an explanation indicator.

The missing plane crashed, because an instrument malfunctioned.

The missing plane crushed because the wreckage was found.

Recognizing Non-arguments

Recognizing Arguments – Not all passages contain arguments. One aim of logic is to distinguish passages that contain arguments from those that do not. In general, a passage contains an argument if it claims to prove something. If it does not do so then it does not contain an argument. Two conditions must be fulfilled for a passage to claim to prove something.

1.) At least one of the statements in the passage must present evidence or reasons for something.

2.)There must be a claim that the evidence or reasons supports something.

Because objects of art are expressive, they are a language.

The proposition Objects of art are expressive is asserted as evidence or reason (premise), and the proposition They are a language is claimed as supported (conclusion) by the evidence of the reason.

Although every passage expressing an argument contains several propositions asserted in it, not every passage in which several propositions are asserted need contain an argument. For an argument to be present, one of the asserted propositions must be claimed to follow from other propositions asserted to be true, which are presented as grounds of, or reasons for believing, the conclusion. This claim may be either explicit or implicit. It may be made explicit by the use of premise indicators or conclusion indicators or by the occurrence of such words as must, should, ought, or necessarily in the conclusion. But the presence of these argument indicators is not always decisive.

Since Henry graduated from medical school, his income is probably very high.

Since Henry graduated from medical school, there have been many changes in medical techniques.

The first argument is an argument but the second is not although both make use of the premise indicator since. The basic structure of the argument can be illustrated thus:

Q because P

If we are interested in establishing the truth of Q, and P is offered as evidence for it, the Q because P formulates an argument. However, if we regard the truth of Q as being unproblematic, as being at least well established as the truth of p, but are interested in explaining why Q is the case, the Q because P is not an argument but an explanation.

Premise and Conclusion

Premise and Conclusion – The terms premise and conclusion denote a function. Thus no proposition taken by itself can be a premise or a conclusion. They are such only within the context of an argument. An argument may be diagrammed simply as follows:

Premise/s--------------------------------> Conclusion

What serves as the evidence what is supposed to follow from the evidence

Premise and conclusion are relative terms. One and the same proposition can be a premise in one argument and a conclusion in another.

All mammals feed their young with milk.

All human are mammals.

Therefore, all humans feed their young with milk.

All that feed their young with milk are mammals.

All humans feed their young with milk.

Therefore all humans are mammals.

There are clues one can use to pick out the conclusions and the premises of an argument. Certain words in our language may be used to signal conclusions or premises. They are called indicators.

PREMISE INDICATORS		CONCLUSION INDICATORS
Since, as indicated by, because, for, in that, may be inferred from, as, seeing that, for the reason that, inasmuch as, given that, may be concluded from, or the reason that, due to the fact that		Therefore, wherefore, accordingly, we may conclude, entails that, hence, thus, consequently, we may infer that, it must be that, whence, so, it follows that, implies that
Premise	Shows that Indicates that Proves that Entails that Implies that Establishes that		Conclusion
Conclusion	Is shown by Is indicated by Is proven by Is entailed by Is implied by Is established by		Premise

An argument is seen more clearly if it is written out in argument form. In this format, the premises are listed first, followed by a solid line separating them from the conclusion, listed at the bottom. Each statement is numbered and the form is as follows:

The president, being human, is mortal, as all human beings are mortal.
Premise 1 Premise 2 ----------- Conclusion	All human beings are mortals. The president is a human being. -------------------------------------- Therefore, the president is mortal.
God does not exist because if he did there would be no suffering and evil in the world; but obviously suffering and evil do exist. Thus, there is not God.
Premise 1 Premise 2 ------------ Conclusion	If God existed there would be no suffering and evil in the world. But obviously suffering and evil do exist. --------------------------------------------------------------------------- Therefore, there is no God