Material Fallacies 1

Robert Harris
Version Date: June 6, 2000


A fallacy is an error in an argument that makes the argument unacceptable. A material fallacy occurs when the argument errs because of how it is expressed, the contents of the expression, or some other flaw. Many times an argument will be expressed unfairly or shift the grounds of evidence.

Perhaps the most important lesson learning about these material fallacies can teach is to pay attention--to scrutinize and analyze the arguments presented to you. Advertisers, politicians, and a host of other would-be persuaders well know that an individual has a strong tendency to hear what he wants to hear and to believe what he wants to believe. When a cold sufferer hears, "Our product temporarily helps relieve some of the symptoms caused by absolutely every known cold virus in the world," he does not really "hear"--pay attention to--the weasels "temporarily," "helps," "some," and "symptoms"; instead he understands that the product will probably cure his cold, regardless of the kind of virus he has. He has not paid attention because he wants to believe that the product will work.

Indeed, before we can examine an argument for truth we must first be assured that we have given careful scrutiny to the meaning of the argument itself. We must ask:

Only by paying attention will you be able to answer these questions "yes." A "no" answer means that you are allowing others to do your thinking for you.

And thinking accurately on your own is especially important at this point: whether or not a particular statement or argument commits a material fallacy is often a matter for careful and discriminating judgment, because the fallacies can imitate right reasoning, and a logical procedure or a reasonable set of assumptions may sometimes at first appear fallacious. Discovering fallacies is so exciting that some people succumb to fallacy frenzy, the temptation to find virtally every argument fallacious. But that is not any better than accepting every argument as good.

For example, when a certain event--say, an assassination--preceded a war, did that event actually cause the war, or would such a conclusion commit the post hoc fallacy or the fallacy of causal reduction? An instant conclusion either way would not be wise. The judgment must arbitrate. And again, if an exercise technique to reduce back pain is described as "relatively effective," is that a genuine attempt to identify the technique's true nature, or is that just an underhanded weasel to avoid making a claim which could be tested for truth? Your own judgment must decide. Just as we must not accept an argument as logical simply because it is put into a form with a logical appearance, so too we must not reject an argument as fallacious simply because it can be arbitrarily squeezed into the form of a fallacy.

In a sentence then, think through the arguments you find and avoid fallacy frenzy.

Unfortunately, in persuasion the world is not the straightforward, face-value place we would like it to be. But by learning to judge arguments, we can keep ourselves from being misled into thinking it is.

Fallacies of Irrelevant Evidence

These fallacies involve the use of arguments or points unrelated to the issue at hand; instead of bringing reason or facts to bear to support or refute a point, they rely upon emotions, prejudices, fears, or other irrational influences. You can best short-circuit such irrelevant appeals by first establishing the exact point at issue and then by determining specifically what kinds of proofs or arguments will rationally support or refute the issue. For example, should we support a political platform because (a) many other people do, (b) someone famous does, or (c) we believe it has the best chance of achieving the goals we approve? Clearly, the first two "reasons" really have nothing to do with an intellectual and reasonable assessment of the situation; they are merely attempts to force us into an irrational response.

Irrelevance. This fallacy has more names than just about any other. The classical logicians called it ignoratio elenchi; its modern names include irrelevant thesis, ignoring the issue, red herring, irrelevant conclusion, diversion, and irrelevant proof. Sometimes when an arguer cannot prove or disprove a particular point, he will simply shift his discussion over to a point that he can prove or disprove, and then imply that the original point has been treated. In one form of irrelevant proof, an arguer may attempt to prove something that has not even been denied, such as a related or incidental fact:

Note especially in this last example that the fallacy is very attractive and often persuasive to the person employing it because it does prove a point or state a true argument, and the point is often related to the issue at hand, sometimes even very closely. The husband here may actually have more or less equated (or confused) material support with love, so that to him the argument appears legitimate.

Sometimes an arguer will oversimplify the original issue so that it is easily rebutted:

Note that the supporting statements of both of these arguments are quite true. However, they are irrelevant because the proponents of the pollution control scheme and the ethics classes certainly would not claim such impossible benefits as mountain pure air or an end to crime.

In another form of this fallacy, a kind of presumptuous disproof, an arguer assumes that he has proved his own point merely by disproving that of his opponent. The underlying questionable assumption here is that one of the two positions must be correct, so that if one can be disproved, the other is established by default. In reality, both may be wrong entirely or only partially right. If you assert that the sky is green and I assert that it is yellow, I cannot prove my position correct by disproving yours. (Compare the fallacy of false dilemma.)

Closely related to this last variety of irrelevance is a procedure in which the arguer disproves a small, inessential part of an opponent's argument and then goes on to conclude that the entire argument must necessarily be invalid or disproved. And, of course, it is only one more step to assume that his own position has thereby been established conclusively: At its most obvious and blatant, the fallacy of irrelevance is often labeled as a "red herring." A red herring is a dried, smoked herring used to distract fox hounds. The herring is dragged across the fox's path and the dogs are led astray by the much stronger scent of the fish. In argument an opponent can be led astray when an arguer injects a word or statement which the opponent is certain to address because of its controversial nature. In this way the opponent is actually partly responsible for the shift from the issue (this is often what keeps arguments going). When an arguer sees that his position is weak or insupportable, he will sometimes use a red herring to lead his opponent off onto something else to argue, even though that something else is irrelevant to the original issue. A fallacy so closely related to irrelevance that it deserves mention here is the fallacy of objections. This fallacy consists in showing that some position, plan, or theory has objections to it, with the implication that it therefore is false or should be rejected. But there are objections to nearly everything, so that is no disproof if the conclusion or proposal has more forceful, positive grounds for it. As Samuel Johnson once noted, if people waited to do something until they had a good answer to every objection, nothing would ever be done.

The Appeal to Ignorance (Argumentum ad Ignorantiam). This fallacy occurs when an arguer asserts that his position is true simply because it cannot be refuted. But a lack of arguments against a position is certainly no support for the position: the burden of proof is always upon the asserter.

Note that in many appeals to ignorance the opposite position can be argued just as plausibly (and of course just as illogically): In the above instances (and in many others) we must logically conclude that we do not know yet. Admitting ignorance is very difficult for many people, and that difficulty makes this fallacy popular.

Sometimes an individual will commit this fallacy by assuming that what is not impossible must be true, since he wishes it to be so. Many people are easy to convince of the "truth" of opinions they wish to be true, and the step from possibility to "fact" is frequently a small one for them. Thus they believe that if something can be established as possible, it must also be true. The cure for this is to distinguish not only between possibility and truth but between possibility and probability. It is possible that a lion will walk in the door and eat you up before you can finish reading this, but it is not at all probable. (I'll bet you're relieved.)

An infinite number of events and conditions are possible; our duty as thinkers is to view them on the scale of reasonable probability and handle them in accordance with that. It is possible for you to be injured by a lion as you read, and it is also possible for you to be injured when the bald tires on your car blow out. But these two possibilities are not equally probable, so you have some basis for choosing whether to spend your money on new tires or on lion-proofing your room.

On the Appeal to Ignorance

All the abuses of the world are engendered upon this, that we are taught to fear to make profession of our ignorance and are bound to accept and allow all that we cannot refute. --Montaigne

Tu Quoque ("You Yourself Do It") and Someone Else Does It. In an attempt to defend himself or evade criticism, an arguer will sometimes accuse his opponent of committing the same crime. If the opponent is guilty of the same thing, the accusation can be quite pointed; but it is still an illogical maneuver since it shifts the argument from the original point at issue and does nothing to establish or refute the original assertion. When a person is guilty of some reprehensible act, it makes no logical difference whether or not his opponent or some third party is also guilty of the same act: the first person is condemnable whether he alone transgressed or the whole world transgressed with him. (This fallacy is popular, of course, because people hope that their guilt will be diluted in the company of others of equal guilt.)

Essentially the same fallacy can be committed by invoking the precedent of a third party--that is, "Someone else does it"--in addition to the arguer or in addition to the person or thing he is defending. The possibility also exists that the circumstances are different for each of the arguers, so that one is permitted to perform some act or function which is forbidden to the other. In a case like this, the tu quoque represents an oversimplification of reality.

Legitimate Comparisons

Where circumstances are (1) exactly alike and (2) represent no crime or immorality, comparing oneself to another is a legitimate form of reasoning, called a pari (from the same root as the word "comparison." An a pari argument is an inference based upon or supported by the same evidence which supports an exactly comparable known fact or given premise. That is, the basic form is, "Since this evidence supports that conclusion, the evidence must in the same way support this conclusion, because the two circumstances are comparable." This kind of reasoning is extremely common. The two potential problems with an a pari argument are first, that the circumstances are not comparable enough to support the inference, and second, that both conclusions are unjust or immoral (making the argument a tu quoque fallacy). In example "k" above, if the bridge had been weakened by the previous car or if my car weighs more than the previous one, the a pari argument would not hold.

Another method of comparison, called a fortiori, argues for a conclusion supported by even stronger evidences or reasons than those supporting a known or given comparable premise. The form is often similar to this: "Since this evidence supports that conclusion, how much more strongly do these greater evidences support this similar conclusion." A fortiori can be extremely effective. For example, in Luke 13:14-16 Jesus points out to the synagogue officials that since they considered it a lawful act of kindness to help an animal on the Sabbath by relieving its thirst, the permission to do good or be compassionate would apply a fortiori (with greater force) to helping a human being by healing him on the Sabbath. That is, if doing a small amount of good (relieving thirst) to a creature of lesser value (animal) was sufficient reason to "work" lawfully on the Sabbath, then the greater reasons--healing the body (large amount of good) of a human being (more value than an animal)--all the more support the conclusion that healing was a lawful "work" on the Sabbath.

The a fortiori argument, is, in fact, one of Jesus' favorite methods of reasoning. In Matthew 7:9-11 he notes that since evil men can feel love toward and do good to their children, then a fortiori a perfect and holy Father in heaven will do much more for his children. Other examples of the Lord's use of this technique are Matthew 6:28-30, Matthew 12:10-12, and Matthew 10:29-31. See also Romans 5:8-10, Romans 5:15-17, Luke 12:6-7, Luke 12:24, and Luke 12:27-28.


Faulty Analogy or False Analogy. Analogies make up one of the most common methods of teaching and arguing because they clarify an unknown or controversial point by comparing it with something familiar. English poet George Herbert noted that "people by what they understand are best led to what they understand not," and Samuel Johnson pointed this out also: "To illustrate one thing by its resemblance to another has been always the most popular and efficacious art of instruction. There is indeed no other method of teaching that of which anyone is ignorant but by means of something already known. . . ."

Analogies can be extremely useful for explaining or clarifying ideas, especially when the idea is an abstraction, for then a concrete, image-creating analogy can allow us to "see the form and shape of a thought." Note how well the analogy helps to make the points understandable in these examples:

Analogies can also be very useful in argument to explain thought processes, to clarify abstract arguments, and to establish the aptness of a conclusion. However, the argument by analogy is often pitifully abused so that several cautions are necessary for constructing and for accepting analogies.

The first point is that no analogy should be intended as a proof or as an indication of logical necessity, because the force of comparison simply cannot be that strong. Rather, a good analogy serves to establish reasonable probability for the conclusion or point being compared--never inescapable certainty. When an analogy is judged to be apt, it leads toward the conclusion the arguer is making. Second, it is always important to recognize the essential unlikeness between the point at issue and the image of the analogy (called the vehicle or sometimes the phoros). However "like" two lines of thought may be, they can never be the same. And lastly, alas, analogies can be rigged easily to create the superficial impression that a particular conclusion is really air tight.

The basic method of analogy is to argue that since two things are similar in one or more ways, they must be similar in some other way or ways. Look at this example from Samuel Johnson:

Johnson here is arguing against those who say, "You shouldn't criticize a play because you couldn't write one any better." His analogy is that, just as you can recognize and judge the quality of a table and criticize the carpenter if the table is not well made, so you can recognize the quality of a play and criticize it if it is not good, though you can neither make a good table yourself nor write a good play. This is an apt analogy because the likenesses between play writing and table making are relevant and because the differences between them are less significant than the similarities.

A faulty analogy, on the other hand, often has insignificant or irrelevant similarities:

While it is true that by taking a fish out of the ocean a person is not stealing the fish, the circumstances are quite different with a parking lot full of cars. Cars have individual owners; cars are not self-reproducing and replenishing; a parking lot is not really much like an ocean.

Sometimes there will be only a single similarity and it may be metaphorical rather than real:

To decide whether an analogy is apt, questionable, or faulty, test it this way:

Testing Analogies

1. Are the similarities significant, and are they pertinent to the argument (as opposed to insignificant and superficial)?
2. Are there multiple points of similarity, and are they more significant than the differences or unlikenesses?
3. Does the analogy argue well only for the proposed conclusion, or could it be used to argue for another or an opposite conclusion?
4. How much strength does the arguer claim for the conclusion? Does he say that the analogy shows the conclusion is possible, very probable, exactly the same, conclusive?

An analogy can be attacked or shown to be faulty in the following ways:

Attacking Faulty Analogies

1. Show that the similarities are trivial. For example, "I refuse to use simplified educational materials for my students. You wouldn't give your children watered-down milk, would you?" This analogy compares making ideas easier to understand with adulterating food, under the premise that both involve a dilution. Since one dilution (the milk) is bad, then so is the other. But the real similarities are too trivial to make this a convincing argument.

2. Show that there are more significant differences than similarities. For example, "Gratifying your sexual desires is the same as gratifying your thirst: you should simply grab a glass of water any time you want it from anywhere you can get it." It is true that both thirst and sexual desire present an urge for gratification, but it does not follow that both urges should be attended to in the same way. A first point of difference is the quality of the urge: water is necessary for life and you will die if you do not eventually answer the call of thirst. Sex presents no such necessity. But more important than this is the difference of consequence. Indiscriminate choice of drinking water can at worst give you a cold or amoebic dysentery, whereas indiscriminate sexual activity can result in psychological or emotional problems, pregnancy, or incurable venereal disease.

3. Rebut or object to the premise given in the vehicle or phoros. In the example above, it could be objected that one should definitely not grab a glass of water from anywhere it can be gotten, since water quality varies from excellent to polluted and since such a taking might be unethical or even illegal. You wouldn't walk into a building and help yourself to the bottled water in someone's private office, would you?

4. Show that the analogy could also argue for the opposite conclusion. For example, "An unborn fetus is no more a person than a coconut is a palm tree." This pro-abortion analogy can be turned over into an anti-abortion one thusly: "Well, a coconut is certainly palm-tree life, the growing offspring of a palm tree, and in the same way an unborn fetus is human life, the growing offspring of a human."

5. Use a counter analogy. For example, "We shouldn't expand our business when our leading competitor is retrenching his. After all, you don't step on the gas when the car in front of you is slowing down." The counter: "That's right, but when the car in front of you slows down, you have the opportunity to pull into the fast lane and pass him."

The last two analogies above, about putting on the brakes or pulling into the fast lane, show the major difficulty with many arguments from analogy. Because the vehicle of the analogy is absolutely and irresistibly true and obvious--you don't step on the gas when the car in front slows down--it can confuse the issue. The mind can be drawn off the point of the argument onto the image of the analogy and become trapped by its forcefulness. But as the counter example shows, these simple and arbitrary analogies can easily be rigged either way. The solution is to analyze the analogy according to the instructions above. Is running a business really significantly like driving down the freeway? And note that in constructing your own analogies you should avoid arbitrary ones with few if any real similarities. Choose analogies with several points of significant similarity.

Mixed Feelings on Analogy

Though analogy is often misleading, it is the least misleading thing we have. --Samuel Butler

Those who reason only by analogies, rarely reason by logic, and are generally slaves to imagination. --Charles Simmons

Analogy, although it is not infallible, is yet that telescope of the mind by which it is marvelously assisted in the discovery of both physical and moral truth. --Charles Caleb Colton

No one will deny the importance of analogy in the workings of the intellect. Yet, though everyone recognizes it as an essential factor in imaginative thinking, it has been viewed with distrust when used as a means of proof.

. . . . . . . . . . . . . . . . . . . . . . . . . . .

Far be it from us to suggest that an analogy cannot serve as point of departure for subsequent verifications. But in this it is no different from any other form of reasoning, since the conclusions of all of them can always be subjected to further testing. . . . Any complete study of argumentation must therefore give it a place as an element of proof. --Chaim Perelman and L. Olbrechts-Tyteca

The Appeal to Pity (Argumentum ad Misericordiam). In place of a legitimate reason or argument, this fallacy substitutes a direct appeal to the emotion of sympathy as the basis for some decision or action. Here is a classic example from attorney Clarence Darrow. Note that he completely ignores the charges of criminal conspiracy against his client:

Here Darrow hopes the jury will think something like, "Poor guy, he ground himself down making other people rich; the least we can do is not put him in prison." Here are some other examples: This appeal can involve an appeal to guilt, too, because to pity someone implies that the sympathizer is better off (in health, luck, education, opportunity, finances) than the person pitied. Thus an appeal can be made that exploits the uneasiness of the sympathizer: As we sit in our comfortable homes in our right minds we should be concerned about the plight of mental patients and the ways to help them. But when we come to decide whether or not compulsory electroshock treatment is desirable or undesirable for helping them, we should use our minds to examine evidence and to think the possibilities through. We do not want to have our decision swayed by emotion rather than evidence.

A variety of the appeal to pity exploits our sympathy for victims and underdogs and is often used by small groups to gain support for unpopular causes. Any small group can describe itself as oppressed, restricted, kept down, shackled, hindered, stifled, or deliberately ignored and offer as proof the fact that no one pays attention to it or grants its demands. Again, however, we want to help those who really are oppressed, and not necessarily those who merely claim to be. And our heads are better at distinguishing the two than are our hearts.

So yes, we do want to care and to consult our feelings, to prevent injustice and to help the unfortunate, for at our best we are beings of compassion and sympathy. We should not turn a deaf ear to cries for help and relief. But our actions should be the products of examination, reflection, and reasoned decision rather than of reaction to our all too easily fooled emotions.

Exercise 1

For each discourse below, name the fallacy or fallacies committed. If the discourse is reasonable and acceptable and therefore contains no fallacy, so state. Feel free to make brief comments pertinent to uncertain or context-dependent cases.

1. You should vote yes on nude public bathing because the human body is not evil--in fact, it is a work of art. Besides, God made the human body. And he made it naked.

2. Look, Fred, sales are declining, the product is outdated, and senior management is living in the past. I don't think we should stay and fight. We're only two people. After all, when the whole building is on fire, you don't try to put it out with a little fire extinguisher: you run for your life.

3. Unless you can prove that this glass breakage occurred by human or natural means, then you must admit that my idea, that ghosts are responsible, is correct. You've already admitted that you can't disprove my idea.

4. This FDA report on health and cholesterol says that eating carrots regularly will be of some help in lowering blood cholesterol. So there may be something to the "carrots are good for you" idea.

5. It is true, ladies and gentlemen, that my client killed his parents for the insurance money, but what comfort can a few dollars be to this poor, wretched man, who is now all alone in the world. Yes, he is now a poor orphan, without a father or mother--all, all alone. Do you feel nothing for his plight?

6. It's true we overcharged our customers on these microwave ovens, but I don't think we should give the money back. After all, the customers would only waste it or spend it on something else.

7. Learning to think well is like learning to paint well: each takes a combination of study and practice. Learn the techniques and fundamentals, and then become better through experience and application.

8. Education is a hard road to drive, full of bumps and potholes and curves, and it goes on a long time. But the road of life is also often bumpy and curvy, so the roughness of the road of education is really preparing you to drive down the road of life.

9. Professor, I don't think you gave me a fair grade on this account of the battle of Midway. Perhaps you didn't know that several of my close relatives were participants in that battle.

10. Since Dissolvit removes bumper sticker adhesive, it will probably remove the adhesive on price tags, too.

Material Fallacies 1 Review

Terms and Concepts

material fallacy
fallacy of irrelevance
red herring
the appeal to ignorance
faulty analogy
appeal to pity
tu quoque
a fortiori
a pari

1. Discuss the pros and cons of using analogies in arguments.

2. What are the methods for deciding whether or not an analogy is acceptable and fair in an argument?

3. How would you attack an unfair analogy?

4. Discuss how you would determine whether a legitimate comparison or a tu quoque fallacy is being committed.

Test Yourself

For each of the following, choose the single best answer.

1. The fact that other scientists are at a loss to explain how the natives learned about Sirius B proves that my theory--that ancient astronauts told the natives--is the correct one. Furthermore, no one can disprove my theory.

A. tu quoque
B. ignorance
C. false analogy
D. pity
E. no fallacy

2. Come on, professor. You're allowed to look at the answers before the test, so we students should be allowed also.

A. tu quoque
B. ignorance
C. false analogy
D. pity
E. no fallacy

3. The staff of the Reader's Digest carefully cuts and trims each article to be included in the Digest, so that, "after skillfully trimming away fat, bone, and gristle, it emerges as a top-quality filet mignon."

A. tu quoque
B. ignorance
C. false analogy
D. pity
E. no fallacy

4. I know I ran the red light at eighty miles an hour, officer, but my boss threatened to fire me if I'm late one more time and I have hungry babies at home and I haven't been feeling well since the accident I had a couple of months ago. I--I hope you'll understand.

A. tu quoque
B. ignorance
C. false analogy
D. pity
E. no fallacy

5. I don't want you ordering anything from that company. It's based in Chicago and Chicago has two baseball teams I don't like.

Answers to Test Yourself: 1B2A3C4D5E

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Robert Harris is a writer and educator with more than 25 years of teaching experience at the college and university level. RHarris at virtualsalt.com