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 Monty Python and the Quest for t he Per fect Fa l lac y

Student Handout #1: Common Fallacies and Booby traps Terms 

•  Argument: a conclusion together with the premises that support it

•  Premise: a reason offered as support for another claim•  Conclusion: the claim, supported by a premise or premises

•  Valid: an argument whose premises genuinely support its conclusion

•  Unsound: an argument that has at least one false premise

•  Fallacy: an argument that relies upon faulty reasoning

•  Booby trap: an argument that, while not a fallacy, might lead an inattentive reader tocommit a fallacy

Examples

Example 1: Whichever basketball team scores the most points will win the game. Virginiascored more points than UNC. Therefore Virginia won the game.

In Example 1, the first two sentences are premises and the third is the conclusion. Theargument is valid, for the two premises provide genuine support for the conclusion.

Example 2: Whichever candidate receives the greatest share of the popular vote will be

elected president of the United States. Al Gore received more votes than George Bush.Therefore, Al Gore was elected president of the United States.

Example 2 has exactly the same structure as Example 1. The first two sentences arepremises, and the third sentence is the argument’s conclusion. The difference, ofcourse, is that in Example 2, the first premise is false. Getting the most votes is not theway one gets elected president. So Example 2 is unsound.

Fallacies Booby trapsGenetic Fallacy: Rejecting an argumentbased on its origins rather than on its ownmerits. A related form accepts or rejects

arguments based on others who endorseor reject those same arguments.

EXAMPLE: You think labor unions aregood? You know who else liked laborunions? Karl Marx, that’s who.

ANALYSIS: The argument rejects laborunions on the grounds that Marx liked

Vagueness: A lack of clarity or precisionin language. Words or groups of words arevague when their meanings are inexact or

when it is unclear to which things the wordor words apply.

EXAMPLE: Your horoscope today: Smalltalk sometimes makes the world go 'round.A casual conversation at work or at adinner party can spark something muchgreater than the sum of its parts. Goahead and talk to multiple people about

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unions without making any reference toany of the present arguments for oragainst labor unions. 

many things.

ANALYSIS: What does it mean for aconversation to “spark something muchgreater than the sum of its parts”? It couldmean just about anything, making the

prediction true, but rather empty. 

Red Herring: An argument that pretendsto establish a particular conclusion but thatreally argues for something else entirely.The origin of the term derives from fox-hunting, where a smoked herring (whichthe smoking process renders red) wouldbe dragged across the trail of the fox tothrow off the hounds.

EXAMPLE: You say that Coach Smith

pressured teachers to give his studentspassing grades. But don’t you agree thatathletics are important to schools? Don’tthey build character?

ANALYSIS: The speaker shifts the subjectfrom Coach Smith’s actions to theimportance of athletics. 

Equivocation: A subcategory ofvagueness that consists of using a term orexpression in an argument in one sense inone place and in another sense in another. EXAMPLE: Any law can be repealed by theproper legal authority. The law of gravity isa law. Therefore, the law of gravity can berepealed by the proper legal authority.

ANALYSIS: The word “law” is being used intwo different senses. 

Straw Man: A subcategory of red herringthat involves misrepresenting anopponent’s position to make it easier to

attack. The origin of the phrase derivesfrom soldiers who learn to use bladedweapons by attacking straw-filled dummies

 – a much easier target than live peoplewho are attempting to stab back.

EXAMPLE: Feminism is part of “a socialist,anti-family political movement thatencourages women to leave theirhusbands, kill their children, practicewitchcraft, destroy capitalism and becomelesbians.” (Statement from Pat Robertson)

ANALYSIS: Well certainly we’d have goodreason to oppose a political movement ofthat sort; fortunately, though, feminismdoes not hold any of those things. 

Suppressed Evidence: A failure tomention or otherwise acknowledgeimportant, relevant evidence. Suppressing

evidence is not always a fallacy (forinstance, defense lawyers areprofessionally obligated to ignore evidenceof their client’s guilt), but ignoring relevantfacts is often a sign of an attempt tomislead.

EXAMPLE: Capital gains taxes keep peoplelocked into their investments rather thanmoving to more productive investments.Someone who has to pay a large tax onher gains may be less inclined to sellstock, leaving her with less money toinvest in new ventures.

ANALYSIS: The problem, of course, is thatselling a stock requires a purchaser forthat stock. So if the holder of sharesdoesn’t sell them, it’s true that she hasless money to reinvest, but it ignores the

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fact that the person who would havebought her shares now has whatevermoney he would have paid her to investelsewhere.

False Cause: Labeling one thing as thecause of another thing on insufficient or

unrepresentative evidence or usingevidence that conflicts with establishedhigher-level truths or theories.

EXAMPLE: Dan White ate a lot of Twinkiesand then killed the Mayor of SanFrancisco. If I were a mayor, I’d banTwinkies so no one would kill me.

ANALYSIS: The argument assumes thateating Twinkies somehow causes mayors

to be assassinated when no such causalconnection has been demonstrated. (Notethat White’s actual murder trial did invokeTwinkies as part of a diminished capacityargument, leading to what is now knownas “the Twinkie defense.” Contrary tolegend, however, the defense did notreally argue that Twinkies caused White tocommit murder. Details are availablehere.) 

Appeal to Authority: Accepting the wordof authorities when we lack good reasons

for thinking that they have the informationwe need or when we think that they mightbe biased, or when we ought to figure thematter out for ourselves, or when theauthority in question is not really an expertin the relevant area.

EXAMPLE: Hi, I’m Troy McClure. You mightremember me from such films as The Day the Peacock Died . After filming sceneswith feathered co-stars all day, there’s

nothing I enjoy more than a bucket ofBuster’s Chicken. It’s chickentastic!

ANALYSIS: While Troy might be an experton making bad films, he has no particularexpertise on fast food. Thus the fact thatTroy McClure enjoys a particular sort offood is not a good reason for thinking that Iought to buy some. 

Undistributed Middle: An argument in

which the middle term is undistributed,meaning that not all the instances of thingsthat are C are also instances of things thatare A or of B. In other words, the firstpremise tells us that everything that is anA is also a C. It doesn’t tell us anythingabout whether things that are C are alsothings that are A. Similarly, in the secondpremise, we are told that everything that isa B is also a C. But again, we knownothing about things that are C.

A is a C.B is a C.Therefore A is a B.

The argument is seductive because of itssurface similarity to a valid argument form:

A is a C.C is a B.Therefore A is a B.

In this argument, we know something

Questionable Use of Statistics:

Employing statistics that are questionablewithout further support. There are severalsubcategories here. Hasty Conclusion:Accepting an argument on the basis of toolittle evidence. Small Sample: Drawingconclusions on the basis of a sample thatis too small to be reliable.Unrepresentative Sample: Reasoningfrom a sample that is not representative ofthe general population.

EXAMPLE: Women shouldn’t be concernedwith wandering around in back alleys atnight, since studies indicate that half of therape committed takes place in the victim’sown home, while only one-twelfth happensin alleys.

ANALYSIS: The argument uses statisticspoorly; the argument is really about the

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about A (namely, that every instance of Ais also an instance of C). And we alsoknow something about C (namely, everyinstance of C is also an instance of B).Since the C is distributed in the secondpremise, we can correctly link A with B.

EXAMPLE: Most Arabs are Muslims and allthe 9/11 hijackers were also Muslims.Therefore most Arabs are hijackers.

ANALYSIS: The conclusion doesn’t followfrom the premises. To show this, substitutethe following argument: My 5-year-oldenjoys watching television, and teenagersalso enjoy watching television. Thereforemy 5-year-old is a teenager. 

likelihood of being raped in a back alley.Since women are in their homes far morefrequently than they are in back alleys, itstands to reason that the sheer number ofrapes will be higher in a victim’s home. Butthat tells us nothing at all about how likely

it is that a woman wandering around aback alley will be raped.