Fallacies

Fallacies are arguments that may sound logical, but are not.  When you look at some of the examples below, you may see some with conclusions you agree with and some you don't.  But the truth, in the empirical sense, is not what is at issue:  What these examples are all about is logical argument.  All these examples are illogical and based in fallacious thinking.

For example, one fallacy is called "sweeping generalization."  Someone may argue:  "That is the richest sorority on campus; so Sue, who belongs to that sorority must be one of the richest women on campus."  Well, Sue may be one of the richest; or she may be one of the poorest.  It doesn't matter whether the conclusion is true or not in the literal sense.  The argument is illogical.  It means nothing at all to say that, if a group has a certain quality, then a member of the group must have that quality, too.

Probably everyone has been guilty of inadvertently using them.  Most of us fall for them even if we know better.  And there are some people (propagandists, advertisers, and many politicians) who use them all the time.  It would be wise to become familiar with the fallacies in order to protect ourselves from the unscrupulous.  But by no means is this list meant to encourage the use of fallacies!


Affirmation of the consequent:   "A implies B, B is true, therefore A is true"  This is confusing, sometimes, because it looks so much like good logic:  "A implies B, A is true, therefore B is true," known as Modus Ponens or affirmation of the antecedent, is one of the basic valid syllogisms.  But affirmation of the consequent is definitely a fallacy:

"If the universe had been created by a supernatural being, we would see order and organization everywhere.  And we do see order, not randomness -- so it's clear that the universe had a creator."

No:  The order could have some other origin.

"If there is indeed a collective unconscious, then we will find that the mythologies of all the world’s cultures have profound commonalities.  And indeed they do -- therefore, there must be a collective unconscious!" 

No:  There may be all sorts of other reasons for mythologies to have commonalities.

This is the converse of denial of the antecedent (below).

A slight variation of affirming the consequent is converting a conditional:  "If A then B, therefore if B then A".  This fallacy is similar to the affirmation of the consequent, but phrased as a conditional statement.

"When educational standards are lowered, the quality of shows on television worsens. So if we see television getting worse over the next few years, we'll know that our educational standards are still falling."

No:  The worsening of television could have other causes.

"If the latest drugs work well, we will see a great improvement n mental health.  So, if mental health improves, we will know that these drugs were effective!" 

No again!  Mental health may improve for other reasons.


Denial of the antecedent:   "A implies B, A is false, therefore B is false"  This is the converse of the fallacy of affirmation of the consequent.  It too looks like good logic:  "A implies B, B is false, therefore A is false," which is called Modus Tollens, or denial of the consequent.  Denial of the antecedent, on the other hand, is illogical:

"If the God of the Bible appeared to me, personally, that would certainly prove that Christianity was true. But God has never appeared to me, so the Bible must be a work of fiction." 

Nope:  God may not appear to you even if the Bible were true.

"If there were such a thing as penis envy, we would expect women to be easier on their sons than on their daughters.  But penis envy is, of course, not real -- so naturally women do not treat their sons better than their daughters." 

No:  They may still do so, just for other reasons.

There is also a version that says “if A, then B, therefore, if not A, then not B.”

“If you have a PhD in psychology, you must be pretty knowledgeable in the field.  Therefore, if you don’t have the PhD, you must be abysmally ignorant of psychology.” 

No:  Having that PhD may mean you have knowledge, but knowledge hardly depends on a degree.


Fallacy of composition:  the idea that a property shared by a number of individual items, is also shared by a collection of those items; or that a property of the parts of an object, must also be a property of the whole thing.

"This new truck is made entirely of lightweight aluminum components, and is therefore very lightweight."

In fact, a truck is composed of so many “lightweight” parts, it is bound to be far from lightweight itself!

"A ton of feathers should weigh less than a ton of lead!"

No:  In fact, they weigh the same - a ton.  Hope you didn't fall for that one!

"Since neurons are either excitatory or inhibitory, the brain itself must have excitatory or inhibitory states."

A variation of composition is the genetic fallacy:  Drawing a conclusion about the goodness or badness of something on the basis of the goodness or badness of the thing’s origin.  (Not actually ad hominem -- see below -- but often listed there)

"The medicine made from that plant must be poisonous, because that plant is poisonous."

"The humanitarian work we do may well come out of our need to look good in front of our fellow man.  So humanitarian work is basically egotistical!"

The opposite of the fallacy of composition is the fallacy of division:  assuming that a property of some thing must apply to its parts;or that a property of a collection of items is shared by each item.

“Humans are conscious and are made of cells; therefore, each cell has consciousness”

"You are studying at a rich college. Therefore you must be rich."

"Since the team could solve the problem so easily, I assume that each member of the team could do it just as well alone."

And a fallacy that totally confuses parts and wholes:  the fallacy of the undistributed middle:  Suggesting that things are in some way similar, but not actually specifing how. A is a kind of C, B is a kind of C, therefore, A is B

"Cats are a form of animal based on carbon chemistry, dogs are a form of animal based on carbon chemistry, so aren't dogs and cats basically identical?"

“They’re both students, so I can expect the same from both.”

"Since they are both schizophrenics, they should both have the same reaction to this new medication."


Sweeping generalization  (The fallacy of accident,  dicto simpliciter):  Applying a general rule to special case;  A general rule is applied to a particular situation, but the features of that particular situation mean the rule is inapplicable.

"Christians generally dislike atheists. You are a Christian, so you must dislike atheists."

Sweeping generalization includes a common misunderstanding the nature of statistics:

“The majority of people in the United States die in hospitals, so stay out of them.”

"Men are statistically more aggressive than women.  Therefore, I, a male, must be more aggressive than you, a female."


Hasty generalization is the converse of sweeping generalization:  A special case is used as the basis of a general rule.  A general rule is created by examining only a few specific cases which aren't representative of all possible cases.

"I know a union representative and he's a terrible person.  I wouldn't trust any of them."

"Jim Bakker was an insincere Christian. Therefore all Christians are insincere."

"This schizophrenic has paranoid delusions.  It stands to reason that they all do."

Hasty generalization includes another common misunderstanding of statistics called the statistics of small numbers:

“My parents smoked all their lives and they never got cancer.”

"The five subjects in our experiment responded well to our intervention.  We can therefore recommend the procedure to everyone."

Another version is called observational selection: pointing out favorable circumstances while ignoring the unfavorable.  For example, at any gambling institution, a great deal of fuss is paid to those who win, while those who lose are quietly encouraged to sneak out the back.  This way, winning seems much more likely that it is!

"All of these people who prayed for a cure survived their disease.  Prayer is clearly to be recommended!"

And observational selection includes anecdotal evidence:

“Just last week I read about a girl who was dying of cancer. Her whole family went to church and prayed for her, and she was cured.  That only proves the power of prayer!"

"Uncle Joe got over his rheumatism by drinking his own urine!"

“Urban myths” are usually good examples!


Bifurcation ("black or white," excluded middle, false dichotomy):  Presuming an either-or distinction. Suggesting that there are only two alternatives, where in fact other alternatives exist or can exist.  Instead of black or white, we can have shades of gray... or even rainbows of colors!

"We must choose between safety and freedom.  And it is in the nature of good Americans to take the risk of freedom."  

Must we choose?  Can't we have both?

"A patient either gets better or they don’t."

"Come on now-- is he or isn’t he bipolar?"

Another form of bifurcation is considering only the extremes:

“He's either guilty or not guilty.”


Begging the question (petitio principii ).  Assuming as a premise the conclusion which you wish to reach. Instead of offering real proof, we can just restate the conclusion we are supposed to come to, and hope the listener doesn't notice.

"Government ownership of public utilities is dangerous, because it is socialistic." 

But government ownership of public utilities is socialism.  You've just been told that it's dangerous because it is what it is.

“We must encourage our youth to worship God to instill moral behavior.”

But does religion and worship actually produce moral behavior?  Of course not!

"Qualitative methods are essentially worthless because they don’t involve measurement or statistics."

The most obvious form of begging the question is the circular argument  (vicious cycle, circulus in demonstrando): Stating in one's proof that which one is supposed to be proving.

"We know that God exists because the Bible tells us so. And we know that the Bible is true because it is the word of God."

"Your arguments against Freud are due to your unresolved unconscious conflicts."

"Your arguments against Skinner are due to your conditioning."

"Your arguments against existentialism are indicative of your inauthenticity."

There’s also the appeal to faith: Faith, by definition, relies on a belief that does not rest on logic or evidence. Faith depends on irrational thought.

"If you accept the Lord, you will understand!"

"If you would only take Maslow at his word, you would finally get it!"

And the most common way to use begging the question is question-begging epithets (loaded words, emotive language, etc.).  Restating the conclusion in "hot" language: 

"This criminal is charged with the most vicious crime known to man." 

Does it prove something, or just get the blood flowing?

Often hard to identify (and so very dangerous) is the ad hoc argument:  Giving an after-the-fact explanation which doesn't apply to other situations.

“I see that John’s cancer is in remission.”
“Yes, our prayers have been answered!”
“But didn’t you pray for Susan, too, and look what happened to her.”
“I’m sure God had a special reason for taking her.”

"Those people who don’t follow the expected pattern of strong-mother/weak-father leading to homosexuality are no doubt hiding their true orientation!"

Look out when people say “everything has a reason” or “God has a purpose for all of us.”


Complex question (loaded question, trick question, leading question, fallacy of interrogation, fallacy of presupposition):  Interrogative form of begging the question (above). Ask a question that leads others to believe that a previous question has been answered in a certain way.

"Answer yes or no:  Did you ever give up your evil ways?" 

If you say yes, that tells us you had evil ways; if you say no, that tells us you still have them.  What if you never had them?

“Have you stopped beating your wife yet?”

"So, are you gay, or just in denial?"

"And when will you come out of the closet?"

A variation on the complex question is the fallacy of many questions (plurium interrogationum) :  This fallacy occurs when someone demands a simple (or simplistic) answer to a complex question.

"Yes or no:  Is democracy ultimately the best system of government?"

Another form of this fallacy is to ask for an explanation of something which is untrue or not yet established.

"How would you explain the presence of aliens on our planet?"


False cause (non causa pro causa, non sequitur): Something is identified as the cause of an event, but it has not actually been shown to be the cause. For example:

"I took an aspirin and prayed to God, and my headache disappeared. So God cured me of the headache."

"Artists often suffered from depression as adolescents.  So, if you want your child to be a great artist, don’t put them on Prozac!"

The most common form of false cause is called post hoc ergo propter hoc:  An inference or conclusion that does not follow from established premises or evidence. Assuming causal connections that haven't been demonstrated.  The Latin phrase means "after this, therefore because of this."

"You should go to Harvard, because Harvard graduates make more money." 

Or could it be that they had more money before they went?

“She got sick after she visited China, so something in China caused her sickness.”

Or could it be that she was sick prior to leaving for China?

“There was an increase of births during the full moon. Therefore, full moons cause birth rates to rise.”

A slight variation is cum hoc ergo propter hoc:  Saying that, because two events occur together, they must be causally related. It's a fallacy because it ignores all the other possible causes of the events.

"Literacy rates have steadily declined since the advent of television. Clearly television viewing impedes learning."

"He started using drugs just about the time he started seeing that girl.  I knew she was a bad influence!"

A common statistical version of this is confusion of correlation and causation:  correlation cannot tell you anything about the direction of causality.  If X is powerfully correlated with Y, X could be the cause of Y, Y could be the cause of X, or (most likely) something else is the cause of both.  Possibly, the relationship is accidental!

“More chess players are men, therefore, men make better chess players than women.”

"Far more women than men suffer from depression. We can assume that there is something about a woman’s physiology that leads to depression."

(Often followed by an ad hoc argument:  The women chess masters must be lesbians; The men with depression must be effeminate!)


Missing the point (irrelevant thesis, ignoratio elenchi, irrelevant conclusion, ignoring the issue, befogging the issue, diversion, red herring, etc.).  Demonstrating a point other than the one at issue.  Diverting attention by changing the subject. Escaped convicts in Elizabethan England would smear themselves with rotten (red) herring to throw the dogs off the scent.

"I fail to see why hunting should be considered cruel when it gives tremendous pleasure to many people and employment to even more." 

So we should stop talking about cruelty and start talking about pleasure and employment?

“Christianity is the only true religion:  It has clearly been of great help to many people."

No matter how well he argues how much it has helped people, he will not have shown that Christian teachings are true.

"It is very clear that we prescribe psycho-active medications to people who don’t really need them.  We should outlaw these drugs altogether!"

One example of missing the point is the straw man: Creating a false scenario and then attacking it.  Misrepresenting someone else's position so that it can be attacked more easily.

“Evolutionists think that everything came about by random chance.  How could that be?”

Most evolutionists think in terms of natural selection which may involve incidental elements, but does not depend entirely on random chance. Painting your opponent with false colors only deflects the purpose of the argument.

"To summarize Freud, he believed that it all boils down to sex.  Let me show you why Freud is therefore full of crap!"

Another example is reification  (hypostatization): when people treat an abstract concept or hypothetical construct as if it represented a concrete event or physical entity.  IQ tests are often presented as actual measures of intelligence, for example.

"What is consciousness?  You can’t find it anywhere in the human brain, so we must reject the concept."

And another example, the meaningless question:

“How high is up?”

"Up" describes a direction, not a measurable entity.

“Does anything really exist?”

"How can we experience the collective unconscious directly?"

A really tricky version of missing the point is the appeal to logic (argumentum ad logicam ):  This is the "fallacy fallacy" of arguing that a proposition is false because it has been presented as the conclusion of a fallacious argument. Remember that fallacious arguments can arrive at true conclusions.

"Take the fraction 16/64. Now, cancelling a six on top and a six on the bottom, we get that 16/64 = 1/4."
"Wait a second! You can't just cancel the six! Your math is wrong:  16/64 does not equal 1/4!"

Yes it does, even though the math is wrong.

Very common are half truths (suppressed evidence): An statement usually intended to deceive that omits some of the facts necessary for an accurate description.

And one of the worst versions of missing the point is false analogy:  An analogy or metaphor illustrates or elaborates; it doesn't prove anything:  

"The American Indian had to make way for Western civilization; after all, you can't make an omelette without breaking a few eggs." 

Are the lives and cultures of millions comparable to eggs?  What does making omelettes have to do with history and morality?

"Since the mind is essentially a wet computer, our task is to figure out how we can best program it!"


There are many fallacies that involve the misuse of words.

Very common is special pleading:  Here, we use a double-standard of words.

"The ruthless tactics of the enemy, his fanatical, suicidal attacks have been foiled by the stern measures of our commanders and the devoted self-sacrifice of our troops." 

Are ruthless tactics different from stern measures?  Fanatical, suicidal attacks from devoted self-sacrifice?  Journalists do this all the time!

"Ellis’s therapy is authoritarian and aggressive!"

"Rogers’s therapy is laissez faire, even lazy!"

This is not far from the fallacy of equivocation:  Use of ambiguous words. A key word is used with two or more different meanings in the same argument.  Shifting the meaning of the words.

"What could be more affordable than free software? But to make sure that it remains free, that users can do what they like with it, we must place a license on it to make sure that will always be freely redistributable."

One way to avoid this fallacy is to choose your terminology carefully before beginning the argument, and avoid words like "free" which have many meanings.

The "no true Scotsman..." fallacy:  Suppose I assert that no Scotsman puts sugar on his porridge. You counter this by pointing out that your friend Angus likes sugar on his porridge. I then say "Ah, yes, but no true Scotsman puts sugar on his porridge."  By disparaging Angus's Scottishness, I basically limit the meaning of the word "Scotsman."

“How can he do that to her if he loves her?”
“Ah, but that’s not true love, see?”

"No caring therapist would use methods like that!"

"No well-trained scientist would come to those conclusions!"

"Christians turn the other cheek."
"But I've seen many Christians return violence for violence."
"Yes, but those aren't good Christians.  They aren't even real Christians at all!"

The previous example includes the use of accent -- changing oral stress within a sentence to alter the meaning.

“All men are created equal...” implies that women are not.
“All men are created equal...” suggests that they don’t end up equal.

An amusing misuse of words is amphiboly -- use of ambiguous sentences.

“Two pizzas for one special price.” Two for one?  Or both at the same “special” price?


Personal attack (argumentum ad hominem):  Attacks the person instead of the argument. In personal attack, we ask the listener not to consider the argument, but to consider where it is coming from:

"This theory about a new cure for cancer has been introduced by a man known for his Marxist sympathies.  I don't see why we should extend him the courtesy of our attention."

"You can’t trust Freud -- he used cocaine!"

"You can’t trust Adler -- he was a socialist!"

"You can’t trust Horney -- she suffered from depression!"

But Marxists, cocaine users, socialists, and depressed people can be right!

Then there’s the abusive form of the personal attack:

"You claim that atheists can be moral -- yet I happen to know that you abandoned your wife and children."

"You don’t agree with experimentation?  I’ve read that you were never able to get any of your own research published!"

A little more clever is the circumstantial form of the personal attack:

"It is perfectly acceptable to kill animals for food. Since you are wearing leather shoes, I am sure you won’t argue with that."

"You don’t agree with Rogers -- yet I notice you use reflection in your own practice!"

Very damaging is poisoning the well:  The personal attack can also be used as an excuse to reject a particular conclusion such as when you allege that someone is rationalizing a conclusion for selfish reasons.  You’ve “poisoned the well” in that, from now on, people will tend to doubt his arguments.

"Of course you'd argue that affirmative action is a bad thing. You're white."

Note that if someone is a known perjurer or liar, that fact will reduce their credibility as a witness. It won't, however, prove that their testimony is false in this case.  Liars can tell the truth!

"Don’t listen to her criticisms of existentialism -- she’s an experimentalist!"

And every teenager's favorite argument is called tu quoque (two wrongs make a right ):  Latin for “you, too!” or "look who's talking!"

"If you think communal living is such a great idea, why aren't you living in a commune?"

"If psychology is so great, how come you have so many problems?"

“If smoking is so bad for you, why do you smoke?”

But even a smoker can know that it isn't good for you!


Appeal to the masses (argumentum ad populum, appealing to the people, mob appeal, appealing to the gallery, appeal to popular pieties).  This involves theatrical appeals to our lowest instincts, such as selfishness, greed, jealousy, or vanity rather than using facts and reasoning... 

"Because you are a college audience, I know I can speak to you about difficult matters seriously." 

Oh, well, thank you very much; please do go on!

One example of appeal to the masses is the bandwagon fallacy (consensus gentium, argumentum ad numerum): concluding that an idea has merit simply because many people believe it or practice it.

“Most people believe in God; therefore, it must be true.”

Simply because many people may believe something says nothing about the fact of that something. Once upon a time, everyone thought the earth was flat!

"All I'm saying is that millions of people believe in astrology, so there must be something to it."

"The enormous popularity of books on dream analysis alone suggests its validity!"

Argument from omniscience:  The "everybody" version of the preceding.

"Everyone knows that men and women are psychologically the same!"

“People need to believe in something. Everyone knows that.”

"Everyone is moving into cognitive style research -- there must be something to it!"

Beware of words like "all," "everyone," "everything."


Appeal to authority (argumentum ad verecundiam): This is where we bring up famous people, reference groups, science, tradition, religion, universality....

“Professor Boeree says behaviorism is dead.”

Simply because an authority says something does not necessarily mean it's correct.  Except, of course, if that authority is me.

The great philosopher Santayana said “Those who remain ignorant of history are doomed to repeat it.”  But Henry Ford said “History is bunk!”  So who is right?

"Freud said....  -- and who are we to argue with a genius of his caliber?"

This includes the famous advertising technique called snob appeal: 

"Camel cigarettes.  They're not for everybody!”

"Chez Merde -- the wine for the true connoisseur!"

"All those who can afford it prefer Freudian therapy!"

Variations include  appeal to tradition (argumentum ad antiquitatem):  This is the fallacy of asserting that something is right or good simply because it's old, or because "that's the way it's always been."  Just because people practice a tradition, says nothing about whether it is true (or good).  See, for example, astrology, slavery, superstition, human sacrifice....

"Psychologists have always agreed that...."

The opposite is called appeal to novelty (argumentum ad novitatem): The fallacy of asserting that something is better or more correct simply because it is new, or newer than something else.

“It’s the latest!”

“Windows Vista is much better than older version of the Windows OS.  How could it not be, coming after so many years of experience!”

"The most recent studies show that...."

The most recent studies are also the ones that have had the least chance of being shown to be mistaken!

Appeal to riches (argumentum ad crumenam):  The fallacy of believing that money is a criterion of correctness; that those with more money are more likely to be right, or that something that costs more is intrinsically better.

"Microsoft software is undoubtedly superior; why else would Bill Gates have gotten so rich?"

“It costs twice as much -- it must be twice as good!”
 
"You get what you pay for!" 

Do you?

"I’ll have to side with the psychiatrists.  After all, they make a lot more money than the PhD psychologists!"

The opposite is appeal to poverty (argumentum ad lazarum):  The fallacy of assuming that someone poor is sounder or more virtuous than someone who's wealthier, or that something inexpensive or plain is somehow naturally better. For example:

"Monks are more likely to possess insight into the meaning of life, as they have given up the distractions of wealth."

“A simple loaf of bread, made lovingly by hand -- what could be better?”

"Since John does so much of his work pro bono, he must be a much more honest therapist."


Appeal to nature (the natural law fallacy):  Arguing that, because human beings are products of the natural world, we must mimic behavior seen in the natural world, and that to do otherwise is 'unnatural'.  A common fallacy in political arguments.

"The natural world is characterized by competition; animals struggle against each other for ownership of limited natural  resources. Capitalism, the competitive struggle for ownership of capital, is simply an inevitable part of human nature. It's how the natural world works."

"Of course homosexuality is unnatural. When's the last time you saw two animals of the same sex mating?"

Actually, that’s much more common than people think - more than 500 species!  But that, too, is irrelevant: What is true for other animals need not be true for us.

"Our attraction to 'beautiful' people parallels the instincts of birds and mammals.  Love, therefore, is nothing but an instinct!"


Appeal to pity (argumentum ad misericordiam): This is an appeal to your tender emotions, your sympathy:  Listen, if you can bear it, to any telethon.  Or listen to advertisements that try to sell computers to parents.

"You wouldn't want your kids to be left behind on the information super-highway, would you?  What kind of parent are you anyway?"

"I did not murder my mother and father with an axe! Please don't find me guilty; I'm suffering enough through being an orphan.”

"Qualitative methods are used by a small group of dedicated researchers working in a hostile environment of experimentalism."


Appeal to ignorance (argumentum ad ignorantiam, argumentum ex silentio):  Arguing that something must be true, simply because it hasn't been proved false. Or arguing that something must be false because it hasn't been proved true. That is, my position is right because there is no evidence against it.  Or yours is wrong because there is no evidence for it.

“We have no evidence that God doesn't exist.  Therefore, he must exist.”

"There is intelligent life in outer space, for no one has been able to prove that there isn't."

 Fact of the matter is, you can't prove the non-existence of something:  No matter how hard you look, I can always say you haven't looked hard enough.  Go ahead:  Prove to me that unicorns don't exist!

"We don’t know whether holistic medicines actually help psychological disorders, so we might as well use them!"

(Followed by an appeal to pity:  "Would you deny people the chance of getting better, just because there’s no evidence?")

A common accompaniment to the appeal to ignorance is shifting the burden of proof:  The burden of proof is always on the person asserting something. Shifting the burden of proof is the fallacy of putting the burden of proof on the person who denies or questions the assertion.  So, when an arguer cannot provide the evidence for his claims, he may challenge his opponent to prove him wrong.

“Prove God doesn't exist, then!”

“Prove UFO's aren't real, then!”

"I believe that homosexuality is based on biological differences -- I dare you to prove me wrong!"


Appeal to fear (argumentum ad baculum, appeal to force):  Don't argue with me, it's dangerous!

"If you do not convict this murderer, one of you may be his next victim." 

(A similar argument is frequently used in deodorant ads!)

“If you don't believe in God, you'll burn in hell”

"You better learn your stats:  You’ll never be able to get your doctorate if you don’t!"

A little more subtle is the argument from adverse consequences:

“The accused must be found guilty, otherwise others will commit similar crimes”

And a common variation is the slippery slope: Arguing that a change in procedure, law, or action, will result in adverse consequences.

“Give ‘em an inch, and they’ll take a mile!”

“Pass the equal rights for women amendment and before you know it, we’ll all be using unisex bathrooms!”

"If we legalize marijuana, then more people would start to take crack and heroin, and we'd have to legalize those too. Before long we'd have a nation full of drug-addicts on welfare. Therefore we cannot legalize marijuana."

“If we allow physician-assisted suicide, then eventually the government will control how we die.”

It does not necessarily follow that just because we make changes that a slippery slope will occur.

"If you start people on Prozac, they will become dependent on it, then on drugs in general, and never learn to deal with their problems on their own!"


Argumentum ad nauseam:  This is the incorrect belief that an assertion is more likely to be true, or is more likely to be accepted as true, the more often it is heard. So an Argumentum ad Nauseam is one that employs constant repetition in asserting something; saying the same thing over and over again until you're sick of hearing it.  See almost any commercial, or take a look at the practice of having children memorizing Bible verses.

"Classical conditioning must be at the root of all learning -- I had that drummed into my head at Penn State!"

“All my life, people have told me: a man doesn’t show weakness!”