Table of Contents
Intro to Phil
Who Am I?

Logic:  Notes

Syllabus Assignments Readings Notes Resources

Thomas Hobbes



Argumentum ad Hominem. Also known as the Appeal to Personal Ridicule, this fallacy is one of the most common fallacies of irrelevant evidence. The ad hominem appeal relies upon character assassination as a substitute for refutation of an opponent's thesis. Of course, a fact is true or false quite independently of the level of intelligence, amount of breeding, personal habits, or degree of fame of its asserter; yet a surprising number of arguers yield to the temptation to attack the reputation or ability or education of an opponent rather than to present arguments. Worse, the attack is often false, and amounts to nothing more than insult and invective.

  • . . .The decision banning home video recording of TV shows was handed down by a three- judge panel (combined I.Q.: 30) of the U. S. Court of Appeals in San Francisco. --Tom Shales
  • Dr. Custer and his colleagues have often been attacked by Peter Ruckman, a preacher from Pensacola, Florida, who is divorced and remarried to a divorcee. . . . --Bob Jones U. publication
  • He who does not honor Darwin inevitably attracts the speculative psychiatric eye. --Garrett Hardin [Note how much easier it is to accuse one's opponents of being mentally ill than to cite evidence to rebut their position.]
  • What we have, then, is a rather small chorus of men standing between the women of this country and equality. One might even refer to them as mental Munchkins. --Ellen Goodman
  • They answered and said to [the blind man who had been healed], "You were born entirely in sins, and are you teaching us?" --John 9:34
  • Well naturally he opposes my position. What can you expect from a third-grade dropout who drinks like a fish, sells drugs to kids, and tortures animals?

Always remember that an argument can be legitimately attacked only by another argument. Truth does not always dwell with our friends, the good, and the sober; it is therefore our duty to look beyond personality and examine fairly whatever assertions, evidences, or positions are put forward.

The ad hominem fallacy has a particular, subtle form which uses the rhetorical device apophasis--pretending to deny what is really being asserted:

  • Although it is obvious from his response, I pass silently over the fact that my opponent has only a high school diploma--and from a rather weak school district at that.
  • I wish to announce that race will not be an issue in this campaign. Just because my opponent is black, I will not encourage the so-called anti-black vote by stressing what a black might do if he were elected.
  • Of course, I don't mean to suggest that you have a rather limited ability to grasp the worth of my project or that you do not have the vision and experience necessary to understand it; I simply would like you to reconsider your stand.

There are two circumstances where non-abusive, factual, personal criticism can be relevant to the issue. The first is commonly found in the courtroom, where the credibility of a witness is sometimes questioned because of his reputation as a liar or because of a demonstrable, overpowering self interest in promoting a certain account of what he has done. Note that such a reputation is significant only in relation to testimony about what the witness did or saw. It has no relevance in connection with his opinions or arguments. Note also that a witness' reputation as a liar (or as a very credible man) is no proof of anything, but merely a relevant factor to be taken into account when evaluating his testimony. A habitual liar can tell the truth and an outstanding citizen can lie. And note finally that even this closely circumscribed, legitimate criticism is often abused. An assertion like, "Don't listen to him; he's a liar," should be considered an ad hominem until the assertion is established as both true and relevant.

The second circumstance where personal character qualities can be relevant involves an estimate of behavior based on personal values. That is, the fact that Jones has been convicted of embezzling money from his employers twice before would be a relevant criticism when considering him for the job of treasurer of the company. And if your local representative has been convicted of taking bribes in exchange for votes, you would not be guilty of an ad hominem if you told others not to vote for him because of what he has done. However, it would be an ad hominem to say, "Congressman Smith's ideas about highway improvement are worthless because he takes bribes." Again, ideas can be attacked only by other ideas or by evidence.

return to top...

Argumentum ad Populum. Also known as the Appeal to the Masses or the Bandwagon Appeal, this argument makes an appeal to a person's sense of belonging or wanting to belong to a particular group. The appeal may be to a political, racial, or religious grouping, but more frequently it involves a social cluster and an address to the beliefs and actions which define the cluster. Peer group pressure, fads, styles, trends, fashions, social acceptability, and fear of ostracization are powerful operators on human behavior and can be used very effectively to manipulate people. People have both a strong desire to belong (since we are social beings) and a general sense of "the normal." The ad populum fallacy takes advantage of this by mistakenly equating a certain popular notion or the mood of a riled-up mob with the normal, true, and acceptable. People are great imitators; they tend to do whatever is "in" and they tend to think whatever is the "right idea." This "human see, human do" phenomenon helps explain everything from goldfish-swallowing fads to the sudden popularity of adultery, and everything from bestselling records to the current focus of literary criticism.

Democracies are especially susceptible to this tyranny of the majority appeal, because political issues are commonly decided by majority vote, and social harmony is maintained partly by each citizen being agreeable. But truth and morality are not determined by popular vote, and to accept ideas or behavior patterns only because they are common can result in nothing less than delusion and oppression. As Anatole France reminds us, "If fifty million people say a foolish thing, it is still a foolish thing." Think for yourself and you will never have to admit that you have become a willing victim of social pressure.

Of course, many things that are commonly believed or promoted are quite true, and it would be foolish to suggest that all traditional beliefs, values, patterns, and so forth should be rejected because they are common (see the next fallacy); the fact is, much of tradition is true, helpful, or valuable precisely because it has been often examined, and those who reject it out of hand are as errant from wisdom as those who accept everything just as it is offered. The point is, then, that you should (1) be suspicious of arguments based largely upon their current popularity, (2) keep your mind operating when you are offered traditional information, and (3) never offer as a proof the fact that something is popular. In other words, keep your back to the wind of popular opinion (plenty of it will blow down your collar anyway), and reexamine your dogmas once a year: the good should be reaffirmed and the bad revised or discarded.

The basis for an ad populum appeal may be true (that is, it could be based on a genuine majority opinion) or it may be simply wishful thinking by the arguer. But whether the claim is true or false, the appeal is designed to create the urge to "jump on the bandwagon." (The propaganda analysts, in fact, call this the bandwagon appeal.)

  • You really must buy one of these new coats--it's the latest style, and everybody's wearing them. You don't want to be left out, do you?
  • Psychology must be the best major because twice as many people major in it as in any other field.
  • "85% of college students smoke pot, says psychiatrist." --That's reason enough, Fred. Here, have a joint.
  • A million people have bought Burnit Toasters, so you know they must be good.
  • Virtually the whole country now believes in flying saucers, so they must exist.
  • According to a recent survey, 88% of those asked believe Breen is guilty. That shows what a crook he is.
  • You're behind the times. Getting drunk is now accepted as normal at every party.
  • Come on, Sally. Everybody's doing it.
  • More people own Kuttchu razors than any other brand.
  • Come on, get with it.
  • All the others in the class want the party in the gym, so don't you think we should have it there, too?

Be careful of phrases such as "best selling," "popular," "America's favorite," "most people agree," and so on. The biggest danger of the ad populum is that this "get with it" philosophy is really an appeal for you to throw away your mind and become a cork on the river of life, floating along without any motion or direction of your own. My advice is, Don't just "go with the flow" unless the flow is going in the right direction. Sir James Barrie sums up: "As soon as you can say what you think and not what some other person has thought for you, you are on the way to being a remarkable man."

return to top...

On Ad Populum

. . . For most minds are the slaves of external circumstances, and conform to any hand that undertakes to mold them, roll down any torrent of custom in which they happen to be caught, or bend to any importunity that bears hard against them.

--Samuel Johnson

The Appeal to Individualism. By a paradox of human nature, we have, along with our desire to belong, an equally strong desire to be independent and unique. We want to be like some people so that we will not feel alienated, but we want to be different from nearly everybody else. Such a situation makes possible a "mass appeal to individualism," where an advertiser, for example, will attempt to sell a product to a considerable number of people by telling them that it will make them different or that it is a product for only a select few. The same kind of appeal, coupled with the adolescent flock urge in young people, can create a trend of major proportions in records, clothes, and even behavior, which then becomes almost a prerequisite for social acceptance in that group: as we have witnessed in the "individualistic" fads and styles of our younger days, a mass desire to be "different" (from another group or generation) often leads to a slavish conformity of the most absurd and bizarre kind.

Actually, the appeal to individualism can be divided into three often interrelated forms. The first is an appeal to be different simply for the sake of being different. It is an appeal against tradition and the common; whatever is common, standard, ordinary should be rejected because it is common, standard, and ordinary--qualities the "individualist" defines as dull and unthinking. But this, of course, is no less reactionary than its ad populum counterpart.

Arguers often exploit this desire for a different drummer by calling upon it and then presenting their own position as that of the true independent thinker. "You should think for yourself," they say, and then, "Here's what you should think." Or, "You know, people who don't follow the mob think this way." The appeal is useful for arguers who find themselves in a minority position. If only a handful of people are buying a particular model of car, the advertiser can appeal to prospects to "be different." A small political faction can gain adherents by telling others not to be "pressed into a mold" or not to imitate those whose ideas have been "stamped out by a cookie cutter." It is pretty easy to characterize the common or majority as humdrum and boring while presenting the alternative as new, different, and original. (Remember the "it's different--I like it" soft drink advertisements?)

  • The anarchist underground is looking for someone who isn't afraid to have his own ideas.
  • This isn't for everybody.
  • Ever get tired of the crowd?
  • They have 31 flavors here and you want chocolate? Everybody eats chocolate. Why not have something different?
  • Are you going to let other people think for you? Make your own decision and support the Flotsam Bill.

A few of the words and phrases used in connection with this form of the appeal to individualism are:

the herd

the crowd

flock of sheep

stand alone


stands apart

one of a kind


The second form of this fallacy occurs as flattery or as a direct appeal to the individual ego: "You're pretty special, and this product is for special people," or "I know you will agree with me because you are so intelligent and well-informed." Sometimes this form uses a challenge: "Are you brave and rugged enough to join our group?"

  • You deserve it. You owe it to yourself.
  • We do it all for you.
  • What's good enough for other folks just isn't good enough for me. --RC Cola ad
  • [Contraceptive ad in teen magazine:] You're old enough to make your own decisions. --S. C. Johnson Co.
  • Children should be told that smoking is for adults. --R. J. Reynolds Tobacco Co.
  • You've got the look. --Jordache

The last form of the appeal to individualism might be characterized as an appeal to personal prestige--to social class, status, or self-importance. There is a certain amount of antiegalitarianism in many people; even in a two-hundred-year-old democracy the feeling that some people are naturally "more equal" than others is still prominent. An appeal to this sense of snobbery or exclusivity can be very effective and has become a major method of selling expensive ("upper class") goods to the aspiring and upwardly mobile middle class. So strong is this sense of snobbery that a bottle of perfume costing five dollars to make sells for forty dollars rather than ten or twelve because people will not buy "cheap" perfume. One condominium developer,who had sold only two units in many months, was told the units were too cheap for the prospective clientele. He doubled the price and sold the whole project in two weeks.

  • This is the car for the man in charge.
  • Your friends will really respect you for joining our exclusive club.
  • I think the better people will support my idea.
  • This new suit will tell others that you have really arrived.

Perhaps we are all to some extent victims of our own hungry egos, of our desire to be someone special, and of the urge to be different just for the sake of novelty. The victimization is relatively harmless when it results only in purchasing a soft drink, soap, or perfume, since psychological satisfaction is a definite (though externally imposed) factor to be reckoned with when enjoying or evaluating a product. But to make a major purchase, or worse, accept an idea or vote a certain way on the basis of an appeal to individualism would be to sacrifice the reason at the altar of vanity and to trade in the truth for a satisfied ego.

Transference. Also called the fallacy of association, this classic fallacy of shifting the argument attempts to persuade the hearer, viewer, or reader by associating with the argument, product, or action something attractive or already acceptable or something unattractive or unacceptable.

Products are packaged in brightly-colored boxes with words like "New!" "Exciting!" and "Powerful!" printed all over them so that a prospective buyer will transfer the evoked positive feelings from the package to the product. Well dressed, good looking spokesmen make other products and ideas attractive and acceptable by being so themselves. In the days when "only prostitutes" dyed their hair, advertisers made hair coloring acceptable, even desirable, by associating it in advertisements with happy children and a contented husband. The woman who dyed her hair had an attractive family life and was loved and accepted.

We transfer our perceptions of externals--happy domestic situations, good looking men, fancy packaging, nice surroundings--to the essences, whether hair dyes, cars, perfume, or philosophies, political stances, and behavioral norms. Our associations demand consistency: a politician who supports motherhood and apple pie must have other good ideas, and a product in an expensive, good looking package must be high quality itself. Unfortunately, believing in transference (or falling for its appeal) opens us to costly and disappointing delusions.

Transference can be divided into several parts just for clarity. The first is the fallacy of external/internal equation, which might also be described as the whitewashed wall fallacy, after the ancient practice of unscrupulous builders who, having made a flimsy wall of loosely piled stones, covered the outside with whitewash to hide the fact that there was no mortar between the stones. This is the fallacy of judging a book by its cover--the external appearance of something is assumed to represent accurately its internal qualities. Needless to say, judging by external appearance or outer form is very foolish, and is becoming more so as the public's willingness to do so is increasingly exploited.

  • Boy, that car looks fast, doesn't it?
  • Look at all the lights and buttons on this receiver! It must be really sophisticated, and certainly better than that one with only half as many controls.
  • I need a really strong cleaner. That one called Ultra Power Dirt Killer in the red bottle with the yellow lightning bolts on it must be best.

A second form of transference works by putting a product or idea in close connection with something attractive or unattractive (depending on whether the idea is to be promoted or attacked). Advertisements often picture the product in a beautiful country setting, around streams or mountains. Politicians often associate their opponents' names with pictures of crime victims, nuclear mushroom clouds, long lines of the unemployed, or the bad section of town. Other politicians distribute pictures of themselves touring new factories, shaking hands with "plain folks," kissing babies, officiating at the opening of a new highway, and so on.

A typical example of this associative appeal is the appeal to sex. There is hardly a more successful method of defeating the reasoning ability and swaying the judgment than to bring sex into the question, whether overtly or through subtle suggestion.

The main form of the appeal to sex is the erotic or carnal appeal--what we might call an appeal to lust. Advertisers use it regularly; the saying, "Sex sells," has proved so true that perhaps a third or more of all advertising uses this appeal in some way. Visual appeals usually show a woman with part of her body uncovered (this is called "cheesecake" in the advertising business), while verbal appeals often rely on double meanings and innuendoes.

  • Give your mouth sex appeal.
  • Take it all off with Rapid Shave.
  • Milk has something for every body.

A milder form of this appeal simply promises or implies social or romantic success. This appeal works well because social opportunities and relationships could always stand improvement.

  • One reason to buy Pioneer Stereo--success with women.

In another form of the appeal to sex, a political appeal to one's own gender attempts to establish solidarity with all men or women and to play on one's pride in being a man or woman.

  • Your opinions on abortion don't count because you're a man.
  • You object only because a woman cannot understand this sort of thing.

The advertisers, too, use this appeal:

  • You've come a long way, baby. --Virginia Slims ad
  • You know it's good for you because you're a woman.
  • Camel Filters. Where a man belongs.
  • Secret Antiperspirant. Strong enough for a man, but made for a woman.

The political pride-in-gender form of the appeal to sex works well because it has combined the appeal to individualism (one sex is independent and different from the other) and the ad populum appeal (all men or all women are one's allies).

Best advice: base your decisions on reasons rather than on anatomy.

Another significant form of the transference or association fallacy is the genetic error. This fallacy makes the mistake of judging an idea's truth or value by the person or institution originating or pronouncing it. But even though an idea might have been originated in the distant past, uttered by a criminal, or formulated by an amateur, it still might be true. And though another idea might have been approved by the latest scientific organization, uttered by a revered forefather, or formulated by an expert, it still may be false. The truth or worth of an idea, especially in areas like morals, politics, and philosophy, must be determined on its own merits; its origin is either completely irrelevant or at best (in the case of scientific discoveries and some expert opinions) a modest indicator of probability.

For some reason, the genetic error is very frequently committed by using quotations from the founders of America (everything they said must be true and right) and from Adolf Hitler or another such villain (everything he said must be wrong and vicious). And depending on individual political leanings and emotional responses to Karl Marx, Joseph Stalin, Mao Tse-Tung, and so forth, these people are also used to "prove" how bad or good, true or false a particular idea must be, because they supposedly originated (or at least uttered) it.

  • "Well, Harry, I think that patriotism is the last refuge of a scoundrel." "Why, Fred, that's a pretty stupid thing to say." "What? Why, the great Samuel Johnson himself said that."
  • "And so, class, you see that persistency, as in so many other things in this world, is the first and the most important condition for success." "That can't true. Adolf Hitler wrote those very same words in Mein Kampf. You're a Nazi, professor."
  • "Aw, you can't believe anything in the newspaper--in fact, truth itself becomes suspicious by being put into that polluted vehicle." "That's pretty exaggerated, don't you think?" "What? How dare you--I was quoting from Thomas Jefferson, one of our great founding fathers."
  • That idea can't be true; it originated in the middle ages.
  • That economic theory can't be any good because it was devised by a history teacher, not an economist.
  • That medical treatment originated among savages in New Zealand, so I guess you can see what it's worth.

Every age has suffered to some extent from modernist snobbery ("Well, we've really arrived now--we must be the only culture ever to have any good ideas") and that has created much of the problem we now call the genetic error. But we must remember that people in distant ages and remote locations were every bit as intelligent as we are, however lacking they might have been in modern technology. Think of the pyramids or Aristotle or Chinese herbal medicine and you will remember that we are not the first generation to do any thinking.

The final form of transference is the appeal to way of life. This appeal attempts to sell happiness or elegance as a concomitant of the product or idea being promoted. You have probably noticed that in almost all advertisements, no matter what the product is, the people pictured are having an astonishingly good time. Idea pushers sometimes use the appeal to way of life to market their wares to people who appear to value happiness or a good time above truth, morality, or justice. The appeal in this form can be quite selfish: "If we convict Button of embezzling those pension funds, his company will no longer support our little league team. Let's let him off."

Typical way of life appeals include claims to "live a little," "have fun," "feel the excitement," and "try a new adventure."

Go for the Gusto!

Motivation researchers are those harlot social scientists who, in impressive psychoanalytic and/or sociological jargon, tell their clients what their clients want to hear, namely, that appeals to human irrationality are likely to be far more profitable than appeals to rationality. --S. I. Hayakawa

return to top...

Begging the Question (Petitio Principii). In its standard form, this fallacy occurs when the initially stated point to be proved (the thesis or assertion) is later used in the argument as an already accepted fact, to support some new point at issue which must be established to prove the initial point. Thus the original statement is eventually used to prove itself true, and hence the other name for this fallacy, circular reasoning. Thesis A is supported by point B; point B is then supported by thesis A (now called fact A).

(Note: The name of this fallacy is often confusing. "Question" here means "issue" rather than "a request for an answer." Thus, a question-begging argument usually has no actual questions in it.)

  • Many intelligent people believe in ghosts. This is clear because several intelligent people told me so. And I know they were intelligent because they all believed in ghosts.
  • All of the best economists follow Keynes. Joseph Line told me, and he's clearly one of the best economists because he follows Keynes.
  • The fossils in this stratum are 200 million years old. How did I date them? Well they are in a stratum of that age. How do I know the stratum is that old? Because it contains these fossils, which are found in strata of that age.

Sometimes essentially the same assertion is changed into different words and used directly as "evidence" to prove itself as first given:

  • Things are worse than before because they are not as good as they used to be.
  • I think Jones is guilty. Why? Because I think he did it.

Another form of this fallacy, known as a question-begging definition, defines a term or phrase in such a way that, when used in an assertion, it proves the assertion true by the very way the term is defined. Any objection to the assertion is silenced by appealing to the definition. For instance, if an arguer says, "All properly informed people oppose mining ocean-floor mineral nodes," anyone named to be in favor of such mining can be declared "not properly informed" by definition. Note the way the following implied definitions are question begging:

  • All high-quality lamps use Snappo switches.
  • Anyone who isn't a complete dunce knows that I am right.
  • All those entitled to judgment will agree with my position on airbags.
  • Books expressing that view are not reliable.
  • The only way to get those results is by sloppy technique.

Question-begging definitions are often the result of stipulative definitions taken to extremes. A stipulative definition is a special, customized meaning given to a word for the sake of exactness or better understanding. Many words are broad or even vague, and stipulative definitions can help to clarify an argument or presentation. For example, no logical problem arises when a writer specifies that "the term 'current technology' shall mean here 'manufactured within the last two years'" or "by 'hardwood cabinet' I mean a cabinet made from boards of solid hardwood but a cabinet made from particle board, even though the particle board is made of hardwood chips." These are both reasonable stipulative definitions, almost certainly not designed to rig an argument. But compare these similar definitions and their arguments:

  • Well, I define current technology as "using the Elmo-Frimpson screw system," and since our company is the only one using that system, we are the only one using current technology.
  • By "hardwood cabinet" I mean "any cabinet containing any hardwood." Our Flimsoplastik speaker cabinets contain hardwood braces inside, so these are therefore "hardwood cabinets."

The test is whether the definition establishes a conclusion automatically and unfairly or whether it is a reasonable definition and clarification of a vague or loose term.

return to top...

Compound Questions. Also called "poisoning the well," this fallacy involves a question which at the same time presents a conclusion or consists of a conclusion in the guise of a question. The fallacy is committed by combining two or more questions which cannot be answered together (hence the name "compound questions"), or more often, by asking a question implying that a previous question has already been asked and answered in a particular way. The compound question thus prevents or avoids any opposing arguments and incriminates the answerer regardless of the response he gives because any answer would admit the preliminary conclusions built into the question. The classic, ancient example is, "Have you stopped beating your wife?" If you say, "no," you admit that you beat her. But if you say, "yes," you also admit that you used to beat her. Note the assumptions behind these questions:

  • How often do you cheat on tests this year?
  • How do you account for your incompetence?
  • Why did you cause the Smiths' divorce?
  • Why do you want war?
  • Are you trying to impose your outdated standards on me?
  • Do you expect me to believe that lie?
  • Where did you hide the murder weapon?
  • Who made God?
  • Have you always been such a fanatic?
  • Why do you always commit logical fallacies when you talk?
  • Why won't you be convinced by obvious truth?

In another form of this fallacy, several questions which may each have a different answer are combined into one question for which a single response is demanded.

  • Mr. Glass, did you or did you not visit the bank that morning--as our witnesses have established--and then rob it later that afternoon? Just answer yes or no.
  • Are you planning to quit your job and thereby doom yourself to failure and despair?
  • Don't you think steamed lobster, boiled ox eyes, and steak with mushrooms are delicious?
  • Aren't you against immoralities like lust, kissing, and adultery?

The response to a compound question, of course, is to refuse to answer it as stated, identifying it as a compound question, and then breaking it down into its various components. Questions which imply previous conclusions should be responded to by objecting to the conclusions: "Have you stopped beating your wife?" "I do not now beat nor ever have beaten my wife."

Note that if a previous question has indeed been asked and answered or if some circumstance establishes the answer to a previous question, a question that implies that previous answer is not fallacious. If someone takes a few shots at you, you are not being illogical to ask, "Why are you trying to shoot me?" If Johnny is always late coming home, his parents are not being illogical to ask, "Why are you always late coming home?"

return to top...

Condition Contrary to Fact. We all have fun speculating on what might have been different if certain events of history or the past had had different outcomes. Of course, we can never be sure what would have happened. A single event is a link in an infinitely branching chain, and to alter that event could result in an incomprehensible number of altered events after it. Thus, all we can do is imagine and guess--probably very inaccurately--what would have been if some circumstance had been different. To insist otherwise--to pretend to know what would have happened--commits the fallacy of condition contrary to fact.

  • If the South had won the Civil War, we would still have slavery.
  • If Tillotson had been appointed to the Federal Reserve Board, the inflation rate would be twice as high.
  • If we had made our toasters hot pink instead of blue, we would have sold twenty million of them instead of only six.
  • If I'd gone to another school, I'd be making straight A's this semester.
  • If Philadelphia had remained the seat of the U.S. government, the publishing industry would be centered there instead of in New York.

In another form of this fallacy, an arguer applies the premise of a conditional syllogism to a circumstance that does not have a necessary or automatic cause-and-effect relationship. We can seldom be sure what will follow a certain proposed event until the event actually occurs. We can argue for probability in such cases, but not for necessity. Note the difference between the premises of acceptable conditional syllogisms like these--

  • If the power remains off for more that 48 hours, the food will spoil.
  • If the system fails to transfer control to the program, the program will not run.

--and these examples of condition contrary to fact:

  • If peanut price supports are eliminated, the price of peanuts will go up, not down.
  • If we reduce the amount of reading required, students will learn less.
  • If the U.S. put a 10,000-man standing army in the Middle East, armed conflict there would stop.
  • If the California Inventory Tax is repealed, business will improve dramatically, and many new warehouses will be built in the state.

Note that any of these last statements would serve very well for the thesis of an essay, in which supporting evidence would help to establish that thesis. But none of the conclusions follow necessarily from the proposed (hypothetical) conditions. As in all other areas of critical thinking, you must use your good judgment to determine how probable each of these claims seems to be.

return to top...

Contradictory Premises. Conclusions are drawn from the interactions of premises: where two premises contradict each other, there can be no interaction and hence no conclusion. Similarly, if the definitions of two terms conflict with or exclude each other, then those two terms cannot be simultaneously ascribed to a single object or event. The classic example of contradictory premises is the question, "What will happen if an irresistible force meets an immovable object?" The problem here is that in a universe where an irresistible force has been defined to exist, there cannot also exist an immovable object, because then the force would not be irresistible. Conversely, if there is discovered or defined such an item as an immovable object, then by definition there can be no such thing as an irresistible force.

This fallacy's most popular appearance is in the form of a challenging question, because questions with contradictory premises are such brain teasers. In each case, though, no answer can be given because the premises cannot both be true.

  • Into what shape of hole would a round square fit?
  • If an object is all black and all white at the same time, what color is it?
  • If an object is both stationary and traveling at an infinite rate of speed, how long will it take to meet itself?
  • If God can do anything, can he make a stone so heavy that he cannot lift it?
  • If God is all powerful, can he put himself out of existence and come back with twice the power he had before?

return to top...

The Fallacy of Self-Refutation. Any statement asserting a universal truth or absolute application must itself be subject to and consistent with the doctrine it advances. Sometimes, however, a statement--especially of epistemological philosophy--logically contradicts the philosophy it advances; that is, the expression or assertion of a "truth" is itself an exception or contradiction to the truth so expressed or asserted. For example, the statement, "All generalizations are false," is itself a generalization, so that if indeed all generalizations are false, the statement itself is false also. Thus the statement refutes itself and is therefore logically impossible. Note that the following statements all commit the fallacy of self-refutation because each one contradicts in itself the assertion it presents.

  • To find truth we must begin without any a priori assumptions. [This statement is an a priori assumption.]
  • Nothing must be admitted as true without empirical verification. [How is this rule to be verified empirically as true? This statement must not be admitted as true by its own requirement.]
  • Nothing can be known with certainty. [Then this statement cannot be known with certainty.]
  • All truth is subjective opinion. [If this statement is an objective conclusion about truth, it contradicts itself; if it is merely a subjective opinion about truth, it bears little weight as a principle of knowledge.]There are no absolutes. [Is this true absolutely? Is it true partly? If this is absolutely true--true in every case--it proves itself false by being an absolute. If it is not true in every case, there must be absolutes which are the exceptions, and thus the statement is still false. The statement expresses an absolute truth and so refutes itself.]
  • Truth does not exist. [In that case, this statement is not true. In any other case, the statement is proved false.]
  • Everything should be questioned and doubted until it is proved. [Then this assertion must be questioned and doubted until it is proved; therefore, the truth of this assertion is in doubt.]
  • Everything I say is a lie. [Then what are we to make of this statement? How reliable is it?]
  • I believe in nothing. [Do you really believe that?]
  • Words convey no meaning--only deeds convey meaning. [Then, of course, this statement is meaningless.] 

return to top...

False Dilemma. This fallacy is also known as false alternatives or the either/or fallacy. We all sometimes get into the habit of viewing life as a series of antitheses: we hear one side of an argument and want to hear the "other" side; one party or position must be "right" and the other must be "wrong." Actually, there may be ten or more sides to an argument, not just two; and one party or position may be a mixture of good, bad, and compromised ideas, just like the other. The real circumstances of life seldom align themselves exactly with our ideals of right and wrong, good and bad, virtue and vice; so we must be careful not to create false alternatives forced into correspondence with these ideals (for example, "This energy bill is either good or bad").

Further, we must resist reducing complex situations and possibilities to only two alternatives (or three or four). Many alternative positions are not diametrically opposed to each other, but may be merely different mixtures of similar ingredients. Thus, to characterize two positions as mutually exclusive can be not only reductive, but completely false. For example, "This is a struggle between safety and liberty," or "You support progress but we support ecology," implies in each case that the two opposed elements cannot be reconciled or co-existent and that the hearer must choose between them.

A false dilemma is not always created by a careless or ignorant arguer. A few arguers purposefully establish such a one-or-the-other choice in order to oppose their position to an obviously false and easily rejectible position, thereby almost forcing agreement with theirs: "We must either put my plan into operation today or face anarchy and bloodshed tomorrow."

  • In today's world you must make a choice between integrity and success.
  • This is another obvious case of capitalism versus the working man.
  • Are you going to marry me or are you going to live a miserable and lonely existence?
  • Which are you for--property rights or human rights?

Be slightly suspicious when you read or hear expressions like, "Our choice is clear--we must have either . . ." or "Which will you have?" They are often followed by a false dilemma. (Do note that not every either/or usage is fallacious: "The patient is either alive or dead" or "Either God exists or he doesn't" are both legitimate oppositions.)

return to top...

The Appeal to Force (Argumentum ad Baculum). This is simply the adult form of arguing the way a bully does: if you don't accept my opinion, I'll punch you in the nose. The arguer demands acceptance of his proposition not because it is true or proved but because there are consequences for rejecting it.

  • If you expect to receive regular promotions here, I suggest you say nothing about our practice of overgrading meat.
  • Vote in the morning; die in the afternoon. --El Salvador guerrilla slogan, 1982
  • You'd better have an abortion, or I'll tell everybody you're a whore and then leave you for good.
  • You don't like our plans for the new Model 21? Well, if you don't like the products our company is planning to bring out, maybe you should be working for someone else. If you can't overcome your negative feelings, let me know and I'll write you a letter of recommendation.
  • I shoot people who don't agree with me. Don't you think that's a good idea?

A variety of the appeal to force is the appeal to fear. This fallacy suggests possible negative occurrences by other agents (rather than direct threats by a bully) and the occurrences can be natural or non-human evils. A healthy, intellectual fear--which we call concern--is good, even necessary; but an emotional, irrational fear, working with stirred-up juices, will often produce poor decisions.

A good example from a few years ago is the tactic some door-to-door salesmen used to promote smoke detectors. The salesman would show his prospect several color pictures of children who had been burned to death in home fires, and then by playing on the feelings of the now suitably horrified prospect, would sell eight or ten detectors at over a hundred dollars each. A calm and rational evaluation of the situation would have resulted in the realization that two or perhaps three detectors would be entirely sufficient for most homes, and further, that they could be bought from a store for less than thirty dollars each. Once again we see the truth of the old maxim, "It costs extra to let your guts do your thinking."

  • Look, if you don't want this car, just say so and we'll get somebody else to buy it. We have several customers waiting already. You know, though, that if you let it go now, it will be gone and you won't get another chance.
  • If you don't want your loved ones to freeze to death next winter, vote for Proposition 3.
  • You don't want to get fried in a nuclear holocaust do you? Support build down. Vote for the disarmament bill.
  • You don't want to get fried in a nuclear holocaust do you? Support deterrence. Vote against the disarmament bill.

return to top...

The Appeal to Prestige (Argumentum ad Verecundiam). The fallacy of this appeal lies in associating an argument or conclusion with the fame, reputation, or prestige of some person or institution, thus making an equation between social status and proof. The argument is intended to take advantage of an audience's ignorance by exploiting its respect for authority.

An appeal to authority can be reasonably grounded when the authority bases his conclusions on examination, experiment, knowledge, or some set of reasons he is competent to judge. The opinions of experts are very good to have. The problem is that it is not always easy to tell when an appeal to authority is reasonably grounded and when it is merely an appeal to prestige--an appeal to the fame or position of the asserter. Has the authority conducted a thorough investigation or is he simply giving his unfounded or even prejudiced opinion?

One of the largest exhibitions of the fallacious appeal to prestige occurs in areas of controversy, where certain complex truths remain only partially understood. Every time a report, study, or article comes out with some new information (or just another opinion), that report is heralded by those whom it pleases as the final truth, proved so by an appeal to the prestige of the issuer. Thus what should have been an ongoing factual debate is rendered a mere battle of reputations. You should believe my truth because I have more famous people supporting it than my opponents have famous people supporting their truth. One long-running example of this is the debate over marijuana. Some authorities believe it causes permanent reduction in intelligence and general brain function while other authorities believe it is no worse than tobacco and maybe better. The ultimate determination ought to be made by objective tests and measurements, and not by comparing credentials.

Here are some common problems to keep in mind when considering or evaluating an appeal to authority:

  • Equally respectable authorities often give conflicting opinions. If one group of competent people is opposed to another, whether the opposition is large or small, a mere authority appeal will not be sufficient for supporting a point.
  • Some realms of knowledge are better for the use of authorities or experts than others. The opinion of an authority on auto repair, chemistry, or electric power generation (areas of reasonably exact knowledge) is much more likely to be useful and persuasive than the opinion of an authority on politics, social movements, or the psychology of television (areas of inexact knowledge). In these latter categories, the appeal too often amounts to a mere appeal to prestige.
  • The authority may be wrong. This is true even in areas of exact knowledge. We might think that scientists, for example, would always be careful to investigate and consider an issue before making a pronouncement. And yet scientists are human. William Harvey's discovery of the circulation of the blood met with prejudiced opposition from various authorities, as did Joseph Lister's argument for the use of antiseptics in surgery. The voice of authority supported belief in phlogiston for many years, dozens of observers "saw" canals full of water on Mars, and the theory of continental drift was once ridiculed by some geologists.

It is natural that we want to know what other people think, particularly the wise and thoughtful and informed, so the use of authorities and their reasons can be helpful, especially when their comments are used to buttress other arguments. An authority appeal by itself will almost always look like (and perhaps be) a mere fallacious appeal to prestige.

So, as useful as the opinion of an expert is, it is still not a substitute for one's own thinking. Always prefer the merits (proofs) for an argument to the fame of its supporters, and always feel free to sift information for yourself.

Note in these examples how the appeal to prestige relies on status rather than evidence:

  • Jensen must be a pretty good senator. After all, he had the support of the President of the United States in the last election.
  • This must be a good football because football star Joe Gridiron endorses it.
  • Pornography must be harmless because a Federal Task Force said it is.
  • As a Ph.D. and president of the American Literary Society, I think this is a good novel.
  • Conductor Arthur Rubenstein recommends this Radio Shack stereo equipment.

A variety of the appeal to prestige is the appeal to misplaced authority. This fallacy uses the reputation of respected authorities as a means of supporting their opinions on matters outside their area of expertise. An authority, however famous and competent and reliable in his field, must be considered an ordinary person in matters outside of it.

  • If you want the opinion of an expert, ask my neighbor, Dr. Keytone. He has a Ph.D. in Chemistry. He will tell you that Joshua Reynolds is a better painter than John Constable.
  • These opinions about world peace must be excellent and profound because they belong to that brilliant, world-famous theoretician Albert Einstein.

The danger of falling for this fallacy is especially acute when an attempt is made to extend an expert's authority into an area which appears to be a part of his own:

  • Famed mathematician picks the new deluxe Mark II as the most accurately engineered and precision-designed car.
  • The Chairman of the Geology Department says that current rock-crushing equipment is poorly designed. [But does he know anything about mechanical engineering or physics?]

On the Appeal to Prestige

Nothing overshadows truth so completely as authority. --Alberti

A Story of Prestige

A horse dealer had an excellent animal for sale, but at the market it attracted no customers. So he went to see the famous horse trainer Po Lo. "In three days no one has noticed my superb horse," he said. "What I'd like you to do is to walk around the horse and inspect it, then walk away--but look back. For this I'll give you a morning's profit from my other sales." Po Lo circled the horse and examined it, walked away, but looked back; and within the day the horse was sold for ten times what it was worth.

--Chan Kuo Ts'e, tr. Moss Roberts

return to top...

Material Fallacy:


return to top...