FALLACIES

FALLACIES -a misleading or false notion, erroneous belief.
- a statement or an argument based on a false or invalid inference.
- a component of an argument which being demonstrably flawed in its logic or form renders the argument invalid in whole.

KINDS OF FALLACIES

FALLACIES OF RELEVANCE
FALLACIES OF AMBIGUITY
FALLACIES OF REASONING
FALLACIES OF LOGIC
FALLACIES OF PRESUMPTION
FALLACIES OF DEBATE

Logical Fallacies

The ability to identify logical fallacies in the arguments of others, and to avoid them in one’s own arguments, is both valuable and increasingly rare. Fallacious reasoning keeps us from knowing the truth, and the inability to think critically makes us vulnerable to manipulation by those skilled in the art of rhetoric.

What is a Logical Fallacy?

A logical fallacy is, roughly speaking, an error of reasoning. When someone adopts a position, or tries to persuade someone else to adopt a position, based on a bad piece of reasoning, they commit a fallacy. I say “roughly speaking” because this definition has a few problems, the most important of which are outlined below. Some logical fallacies are more common than others, and so have been named and defined. When people speak of logical fallacies they often mean to refer to this collection of well-known errors of reasoning, rather than to fallacies in the broader, more technical sense given above.

Formal and Informal Fallacies

There are several different ways in which fallacies may be categorised. It’s possible, for instance, to distinguish between formal fallacies and informal fallacies.

Formal Fallacies (Deductive Fallacies)

Philosophers distinguish between two types of argument: deductive and inductive. For each type of argument, there is a different understanding of what counts as a fallacy.

Deductive arguments are supposed to be water-tight. For a deductive argument to be a good one (to be “valid”) it must be absolutely impossible for both its premises to be true and its conclusion to be false. With a good deductive argument, that simply cannot happen; the truth of the premises entails the truth of the conclusion.

The classic example of a deductively valid argument is:

(1) All men are mortal.
(2) Socrates is a man.
Therefore:
(3) Socrates is mortal.

It is simply not possible that both (1) and (2) are true and (3) is false, so this argument is deductively valid.

Any deductive argument that fails to meet this (very high) standard commits a logical error, and so, technically, is fallacious. This includes many arguments that we would usually accept as good arguments, arguments that make their conclusions highly probable, but not certain. Arguments of this kind, arguments that aren’t deductively valid, are said to commit a “formal fallacy”.

Informal Fallacies

Inductive arguments needn’t be as rigorous as deductive arguments in order to be good arguments. Good inductive arguments lend support to their conclusions, but even if their premises are true then that doesn’t establish with 100% certainty that their conclusions are true. Even a good inductive argument with true premises might have a false conclusion; that the argument is a good one and that its premises are true only establishes that its conclusion is probably true.

All inductive arguments, even good ones, are therefore deductively invalid, and so “fallacious” in the strictest sense. The premises of an inductive argument do not, and are not intended to, entail the truth of the argument’s conclusion, and so even the best inductive argument falls short of deductive validity.

Because all inductive arguments are technically invalid, different terminology is needed to distinguish good and bad inductive arguments than is used to distinguish good and bad deductive arguments (else every inductive argument would be given the bad label: “invalid”). The terms most often used to distinguish good and bad inductive arguments are “strong” and “weak”.

An example of a strong inductive argument would be:

(1) Every day to date the law of gravity has held.
Therefore:
(2) The law of gravity will hold tomorrow.

Arguments that fail to meet the standards required of inductive arguments commit fallacies in addition to formal fallacies. It is these “informal fallacies” that are most often described by guides to good thinking, and that are the primary concern of most critical thinking courses and of this site.

Logical and Factual Errors

Arguments consist of premises, inferences, and conclusions. Arguments containing bad inferences, i.e. inferences where the premises don’t give adequate support for the conclusion drawn, can certainly be called fallacious. What is less clear is whether arguments containing false premises but which are otherwise fine should be called fallacious.

If a fallacy is an error of reasoning, then strictly speaking such arguments are not fallacious; their reasoning, their logic, is sound. However, many of the traditional fallacies are of just this kind. It’s therefore best to define fallacy in a way that includes them; this site will therefore use the word fallacy in a broad sense, including both formal and informal fallacies, and both logical and factual errors.

Taxonomy of Fallacies

Once it has been decided what is to count as a logical fallacy, the question remains as to how the various fallacies are to be categorised. The most common classification of fallacies groups fallacies of relevance, of ambiguity, and of presumption.

Arguments that commit fallacies of relevance rely on premises that aren’t relevant to the truth of the conclusion. The various irrelevant appeals are all fallacies of relevance, as are ad hominems.

Arguments that commit fallacies of ambiguity manipulate language in misleading ways. Straw man arguments, for example, commit a fallacy of ambiguity.

Arguments that commit fallacies of presumption contain false premises, and so fail to establish their conclusion. For example, arguments based on false dilemmas and circular arguments both commit fallacies of presumption.

These categories have to be treated quite loosely. Some fallacies are difficult to place in any category; others belong in two or three. The ‘No True Scotsman’ fallacy, for example, could be classified either as a fallacy of ambiguity (an attempt to switch definitions of “Scotsman”) or as a fallacy of presumption (it begs the question, reinterpreting the evidence to fit its conclusion rather than forming its conclusion on the basis of the evidence).

Fallacies of Language

Equivocation - words w/ more than one meaning can lead to a false conclusion.

Amphiboly - exploiting ambiguity in grammatical structure to lead to a false or questionable conclusion.

Emotive language -manipulating the connotative meaning of words to establisha claim without a proof.

Example of equivocation :
-You shouldnt take a course that teaches you how to argue, You argue too much already.
-You can get a FREE college education by investing now in mutual funds.

Example of amphiboly :
- I most enthusiastically recommend this candidate with no qualifications whatsoever.
-I can assure that no person would be better for this job.

Example of emotive language :
-Try this new, lower fat double bacon cheese burger.-This is a breakthrough way to become a financially secure. Pick up the phone right now and open the door to new opportunities.

Fallacies of reasoning

Logical Fallacies: Arguments, Reasoning, and the Fallacy
Fallacies are defects in an argument that cause it to be invalid, unsound, or weak. In a deductive argument, the existence of a fallacy means that the argument is not valid - even if the premises are true, the conclusion might still be false. A fallacy does not guarantee it is false; a fallacious argument fails to provide a good reason to believe the conclusion, even if that conclusion is correct.

Fallacies of presumption

FALLACIES OF PRESUMPTION
Fallacies of PresumptionExplanationFallacies of presumption are not errors of reasoning in the sense of logical errors, but are nevertheless commonly classed as fallacies. Fallacies of presumption begin with a false (or at least unwarranted) assumption, and so fail to establish their conclusion.ExamplesArguments involving false dilemmas, complex questions, or circularity all commit fallacies of presumption: false dilemmas assume that there are no other options to consider; complex questions assume that a state of affairs holds when it may not; circular arguments assume precisely the thing that they seek to prove. In each case, the assumption is problematic, and prevents the argument from establishing its conclusion.

Unwarranted Assumptions
The fallacies of presumption also fail to provide adequate reason for believing the truth of their conclusions. In these instances, however, the erroneous reasoning results from an implicit supposition of some further proposition whose truth is uncertain or implausible. Again, we'll consider each of them in turn, seeking always to identify the unwarranted assumption upon which it is based.
Accident
The fallacy of accident begins with the statement of some principle that is true as a general rule, but then errs by applying this principle to a specific case that is unusual or atypical in some way.
Women earn less than men earn for doing the same work.
Oprah Winfrey is a woman.
Therefore, Oprah Winfrey earns less than male talk-show hosts.As we'll soon see, a true universal premise would entail the truth of this conclusion; but then, a universal statement that "Every woman earns less than any man." would obviously be false. The truth of a general rule, on the other hand, leaves plenty of room for exceptional cases, and applying it to any of them is fallacious.
Converse Accident
The fallacy of converse accident begins with a specific case that is unusual or atypical in some way, and then errs by deriving from this case the truth of a general rule.
Dennis Rodman wears earrings and is an excellent rebounder.
Therefore, people who wear earrings are excellent rebounders.It should be obvious that a single instance is not enough to establish the truth of such a general principle. Since it's easy for this conclusion to be false even though the premise is true, the argument is unreliable.
False Cause
The fallacy of false cause infers the presence of a causal connectionsimply because events appear to occur in correlation or (in the post hoc, ergo propter hoc variety) temporal succession.
The moon was full on Thursday evening.
On Friday morning I overslept.
Therefore, the full moon caused me to oversleep.Later we'll consider what sort of evidence adequately supports the conclusion that a causal relationship does exist, but these fallacies clearly are not enough.
Begging the Question (petitio principii)
Begging the question is the fallacy of using the conclusion of an argument as one of the premises offered in its own support. Although this often happens in an implicit or disguised fashion, an explicit version would look like this:
All dogs are mammals.
All mammals have hair.
Since animals with hair bear live young, dogs bear live young.
But all animals that bear live young are mammals.
Therefore, all dogs are mammals.Unlike the other fallacies we've considered, begging the question involves an argument (or chain of arguments) that is formally valid: if its premises (including the first) are true, then the conclusion must be true. The problem is that this valid argument doesn't really provide support for the truth its conclusion; we can't use it unless we have already granted that.
Complex Question
The fallacy of complex question presupposes the truth of its own conclusion by including it implicitly in the statement of the issue to be considered:
Have you tried to stop watching too much television?
If so, then you admit that you do watch too much television.
If not, then you must still be watching too much television.
Therefore, you watch too much television.In a somewhat more subtle fashion, this involves the same difficulty as the previous fallacy. We would not willingly agree to the first premise unless we already accepted the truth of the conclusion that the argument is supposed to prove.

fallacies of relevance

FALLACIES OF RELEVANCE - When an argument relies on premisses that are not relevant to its conclusion, and that therefore cannnot possibly establish its truth...Fallacy of relevance > Ad Hominem ArgumentsAlternative name: Insults and personal attacksEXPLANATION:The most common and well-known version of the ad hominem fallacy is just a simple insult, and is called the abusive ad hominem. It occurs whenever a person has given up attempting to persuade a person or an audience about the reasonable of a position and is not resorting to mere personal attacks.Examples and Discussion:Whenever you see personal attacks and abusive ad hominem arguments being used in a discussion, it is unlikely that anything productive will come out of it in the end. A person who can only make their case by attacking others probably doesn't have much of case to begin with.1. Who cares what you think about movies? You're just an ignorant American who doesn't know anything about real culture.2. You have claimed that John Edward doesn't really talk to the dead, but how can we believe what an atheist says?In both cases, something objectionable is identified about a person: one is an ignorant American, the other is an atheist. The arguer then goes on to conclude that, just because of this objectionable fact, what they say about a particular topic should be ignored.Instead of showing where the people have made an error in any of their statements, the argument simply attacks them for who they are, and claims that we can dismiss anything said without even considering it. But in neither case is this objectionable fact related to the topic at hand - especially when these "objectionable" facts are just plain insults.The proper way to evaluate the merits of an argument is by looking at what the argument says, not by distracting people's attention from the argument by insulting the person and then, unreasonably, concluding that your insult is a good reason to dismiss the argument

fallacies of ambiguity

Fallacies of AmbiguityAmbiguous LanguageIn addition to the fallacies of relevance and presumption we examined in our previous lessons, there are several patterns of incorrect reasoning that arise from the imprecise use of language. An ambiguous word, phrase, or sentence is one that has two or more distinct meanings. The inferential relationship between the propositions included in a single argument will be sure to hold only if we are careful to employ exactly the same meaning in each of them. The fallacies of ambiguity all involve a confusion of two or more different senses.EquivocationAn equivocation trades upon the use of an ambiguous word or phrase in one of its meanings in one of the propositions of an argument but also in another of its meanings in a second proposition.Really exciting novels are rare.But rare books are expensive.Therefore, Really exciting novels are expensive.Here, the word "rare" is used in different ways in the two premises of the argument, so the link they seem to establish between the terms of the conclusion is spurious. In its more subtle occurrences, this fallacy can undermine the reliability of otherwise valid deductive arguments.AmphibolyAn amphiboly can occur even when every term in an argument is univocal, if the grammatical construction of a sentence creates its own ambiguity.A reckless motorist Thursday struck and injured a student who was jogging through the campus in his pickup truck.Therefore, it is unsafe to jog in your pickup truck.In this example, the premise (actually heard on a radio broadcast) could be interpreted in different ways, creating the possibility of a fallacious inference to the conclusion.AccentThe fallacy of accent arises from an ambiguity produced by a shift of spoken or written emphasis. Thus, for example:Jorge turned in his assignment on time today.Therefore, Jorge usually turns in his assignments late.Here the premise may be true if read without inflection, but if it is read with heavy stress on the last word seems to imply the truth of the conclusion.CompositionThe fallacy of composition involves an inference from the attribution of some feature to every individual member of a class (or part of a greater whole) to the possession of the same feature by the entire class (or whole).Every course I took in college was well-organized.Therefore, my college education was well-organized.Even if the premise is true of each and every component of my curriculum, the whole could have been a chaotic mess, so this reasoning is defective.Notice that this is distinct from the fallacy of converse accident, which improperly generalizes from an unusual specific case (as in "My philosophy course was well-organized; therefore, college courses are well-organized."). For the fallacy of composition, the crucial fact is that even when something can be truly said of each and every individual part, it does not follow that the same can be truly said of the whole class.DivisionSimilarly, the fallacy of division involves an inference from the attribution of some feature to an entire class (or whole) to the possession of the same feature by each of its individual members (or parts).Ocelots are now dying out.Sparky is an ocelot.Therefore, Sparky is now dying out.Although the premise is true of the species as a whole, this unfortunate fact does not reflect poorly upon the health of any of its individual members.Again, be sure to distinguish this from the fallacy of accident, which mistakenly applies a general rule to an atypical specific case (as in "Ocelots have many health problems, and Sparky is an ocelot; therefore, Sparky is in poor health"). The essential point in the fallacy of division is that even when something can be truly said of a whole class, it does not follow that the same can be truly said of each of its individual parts.Avoiding FallaciesInformal fallacies of all seventeen varieties can seriously interfere with our ability to arrive at the truth. Whether they are committed inadvertently in the course of an individual's own thinking or deliberately employed in an effort to manipulate others, each may persuade without providing legitimate grounds for the truth of its conclusion. But knowing what the fallacies are affords us some protection in either case. If we can identify several of the most common patterns of incorrect reasoning, we are less likely to slip into them ourselves or to be fooled by anyone else.

COMMON FALLACIES IN REASONING1. FAULTY CAUSE: (post hoc ergo propter hoc) mistakes correlation or association for causation, by assuming that because one thing follows another it was caused by the other.example: A black cat crossed Babbs' path yesterday and, sure enough, she was involved in an automobile accident later that same afternoon.example: The introduction of sex education courses at the high school level has resulted in increased promiscuity among teens. A recent study revealed that the number of reported cases of STDs (sexually transmitted diseases) was significantly higher for high schools that offered courses in sex education than for high schools that did not.2. SWEEPING GENERALIZATION: (dicto simpliciter) assumes that what is true of the whole will also be true of the part, or that what is true in most instances will be true in all instances.example: Muffin must be rich or have rich parents, because she belongs to ZXQ, and ZXQ is the richest sorority on campus.example: I'd like to hire you, but you're an ex-felon and statistics show that 80% of ex-felons recidivate.3. HASTY GENERALIZATION: bases an inference on too small a sample, or on an unrepresentative sample. Often, a single example or instance is used as the basis for a broader generalization.example: All of those movie stars are really rude. I asked Kevin Costner for his autograph in a restaurant in Westwood the other evening, and he told me to get lost.example: Pit Bulls are actually gentle, sweet dogs. My next door neighbor has one and his dog loves to romp and play with all the kids in the neighborhood!4. FAULTY ANALOGY: (can be literal or figurative) assumes that because two things, events, or situations are alike in some known respects, that they are alike in other unknown respects.example: What's the big deal about the early pioneers killing a few Indians in order to settle the West? After all, you can't make an omelette without breaking a few eggs.example: Banning "head" shops from selling drug paraphernalia in order to curb drug abuse makes about as much sense as banning bikinis to reduce promiscuity.5. APPEAL TO IGNORANCE: (argumentum ad ignorantiam) attempts to use an opponent's inability to disprove a conclusion as proof of the validity of the conclusion, i.e. "You can't prove I'm wrong, so I must be right."example: We can safely conclude that there is intelligent life elsewhere in the galaxy, because thus far no one has been able to prove that there is not.example: The new form of experimental chemotherapy must be working; not a single patient has returned to complain.6. BIFURCATION: (either-or, black or white, all or nothing fallacy) assumes that two categories are mutually exclusive and exhaustive, that is, something is either a member of one or the other, but not both or some third category.example: Either you favor a strong national defense, or you favor allowing other nations to dictate our foreign policy.example: It’s not TV. It’s HBO.7. FALSE DILEMMA: (a form of bifurcation) implies that one of two outcomes is inevitable, and both have negative consequences.example: Either you buy a large car and watch it guzzle away your paycheck, or you buy a small car and take a greater risk of being injured or killed in the event of an accident.example: You can put your money in a savings account, in which case the IRS will tax you on the interest, and inflation will erode the value of your money, or you can avoid maintaining a savings account in which case you will have nothing to fall back on in a financial emergency.8. FAULTY SIGN: (also includes argument from circumstance) wrongly assumes that one event or phenomenon is a reliable indicator or predictor of another event or phenomenon.example: the cars driving in the opposite direction have their lights on; they must be part of a funeral procession.example: That guy is wearing a Raiders jacket and baggy pants. I’ll bet he’s a gang member.9. DAMNING THE SOURCE: (ad hominem, sometimes called the genetic fallacy) attempts to refute an argument by indicting the source of the argument, rather than the substance of the argument itself.example: There is no reason to listen to the arguments of those who oppose school prayer, for they are the arguments of atheists!example: The American Trial Lawyers Association favors of this piece of legislation, so you know it has to be bad for ordinary citizens.10. TU QUOQUE: (look who's talking or two wrongs make a right) pointing to a similar wrong or error committed by another.example: Gee, Mom and Dad, how can you tell me not to do drugs when you both smoke cigarettes and drink alcohol?example: The United States has no business criticizing the human rights policies of the Third World nations, not as long as discrimination and segregation continue to exist in the United States.11. EQUIVOCATION: allows a key word or term in an argument to shift its meaning during the course of the argument. The result is that the conclusion of the argument is not concerned with the same thing as the premise(s).example: Only man is rational. No woman is a man. Therefore, no woman is rational.example: No one who has the slightest acquaintance with science can reasonably doubt that the miracles in the Bible actually took place. Every year we witness countless new miracles in the form recombinant DNA, micro-chips, organ transplants, and the like. (the word "miracle" does not have the same meaning in each case)12. BEGGING THE QUESTION: (petitio principii) entails making an argument, the conclusion of which is based on an unstated or unproven assumption. In question form, this fallacy is known as a COMPLEX QUESTION.example: Abortion is murder, since killing a baby is an act of murder.example: Have you stopped beating your wife?13. TAUTOLOGY: (a sub-category of circular argument) defining terms or qualifying an argument in such a way that it would be impossible to disprove the argument. Often, the rationale for the argument is merely a restatement of the conclusion in different words.example: The Bible is the word of God. We know this because the Bible itself tells us so.example: You are a disagreeable person and, if you disagree with me on this, it will only further prove what a disagreeable person you are.14. APPEAL TO AUTHORITY: (ipse dixit also called ad verecundiam sometimes) attempts to justify an argument by citing a highly admired or well-known (but not necessarily qualified) figure who supports the conclusion being offered.example: If it's good enough for (insert celebrity's name here), it's good enough for me.example: Laws against marijuana are plain silly. Why, Thomas Jefferson is known to have raised hemp on his own plantation.15. APPEAL TO TRADITION: (don't rock the boat or ad verecundiam) based on the principle of "letting sleeping dogs lie". We should continue to do things as they have been done in the past. We shouldn't challenge time-honored customs or traditions.example: Of course we have to play "pomp and circumstance" at graduation, because that's always been the song that is played.example: Why do I make wine this way? Because my father made wine this way, and his father made wine this way.16. APPEAL TO THE CROWD: (ad populum or playing to the gallery) refers to popular opinion or majority sentiment in order to provide support for a claim. Often the "common man" or "common sense" provides the basis for the claim.example: all I can say is that if living together is immoral, then I have plenty of company.example: Professor Windplenty's test was extremely unfair. Just ask anyone who took it.17. STRAW MAN: stating an opponent's argument in an extreme or exaggerated form, or attacking a weaker, irrelevant portion of an opponent's argument.example: A mandatory seat belt law could never be enforced. You can't issue citations to dead people.example: What woman in her right mind could truly desire total equality with men? No woman wants the right to be shot at in times of war, the right to have to pay alimony, or the right to have to use the same restrooms as men.18. SLIPPERY SLOPE: (sometimes called a snowball argument or domino theory) suggests that if one step or action is taken it will invariably lead to similar steps or actions, the end results of which are negative or undesirable. A slippery slope always assume a chain reaction of cause-effect events which result in some eventual dire outcome.example: If the Supreme Court allows abortion, next think you know they'll allow euthanasia, and it won't be long before society disposes of all those persons whom it deems unwanted or undesirable.example: If I let one student interrupt my lecture with a question, then I'll have to let others and, before long, there won't be any time left for my lecture.19. APPEALING TO EXTREMES: A fallacy very similar to slippery slope, which involves taking an argumentative claim or assertion to its extreme, even though the arguer does not advocate the extreme interpretation. The difference between the two fallacies is that appealing to extremes does not necessarily involve a sequence of causal connections.example: Husband to ex-wife: Well, if you want to be completely fair about dividing everything up, you should get one of my testicles and I should get one of your breasts!example: Debtor to creditor: Hey, you've already repossessed my car and my television. Why don't you just draw a quart of blood or carve a pound of flesh from my heart too?20. HYPOTHESIS CONTRARY TO FACT: This fallacy consists of offering a poorly supported claim about what might have happened in the past or future if circumstances or conditions were other than they actually were or are. The fallacy also involves treating hypothetical situations as if they were fact.example: If you had only tasted the stewed snails, I'm sure you would have liked them.example: If Hitler had not invaded Russia and opened up two military fronts, the Nazis would surely have won the war.21. NON SEQUITAR: (literally means "does not follow") in a general sense any argument which fails to establish a connection between the premises and the conclusion may be called a non-sequitar. In practice, however, the label non-sequitar tends to be reserved for arguments in which irrelevant reasons are offered to support a claim.example: I wore a red shirt when I took the test, so that is probably why I did so well on the test.example: Mr Boswell couldn't be the person who poisoned our cat, Truffles, because when I used to take Truffles for walks he always smiled and said "Hello" when we walked by.22. RED HERRING: attempting to hide a weakness in an argument by drawing attention away from the real issue. A red herring fallacy is thus a diversionary tactic or an attempt to confuse or fog the issue being debated. The name of the fallacy comes from the days of fox hunting, when a herring was dragged across the trail of a fox in order to throw the dogs off the scent.example: accused by his wife of cheating at cards, Ned replies "Nothing I do ever pleases you. I spent all last week repainting the bathroom, and then you said you didn't like the color."example: There's too much fuss and concern about saving the environment. We can't create an Eden on earth. And even if we could, remember Adam and Eve got bored in the Garden of Eden anyway!23. INCONSISTENCY: advancing an argument that is self-contradictory, or that is based on mutually inconsistent premises.Example: A used car salespersons says, "Hey, you can’t trust those other car salesman. They’ll say anything to gt you to buy a car from them."Example: A parent has just read a child the story of Cinderella. The child asks, "If the coach, and the footmen, and the beautiful clothes all turned back into the pumpkin, the mice, and the rags, then how come the glass slipper didn’t change back too?"

Examples of Fallacies:
Inductive Argument
Premise 1: Most American cats are domestic house cats. Premise 2: Bill is an American cat. Conclusion: Bill is domestic house cat.
Factual Error
Columbus is the capital of the United States.
Deductive Fallacy
Premise 1: If Portland is the capital of Maine, then it is in Maine. Premise 2: Portland is in Maine. Conclusion: Portland is the capital of Maine. (Portland is in Maine, but Augusta is the capital. Portland is the largest city in Maine, though.)
Inductive Fallacy
Premise 1: Having just arrived in Ohio, I saw a white squirrel. Conclusion: All Ohio Squirrels are white. (While there are many, many squirrels in Ohio, the white ones are very rare).