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What is a Logical Fallacy? A Logical fallacy is an argument that makes a flaw or error in its reasoning. Using logic – and knowing about fallacies – is a potent and formidable tool one can use, in both debate and in life. Pointing out a logical fallacy can take out what was before a formidable, “undefeatable” argument, claim, or study.

There are many different words or expressions for a fallacy:

  • Flawed
  • Fallacious
  • Does not Follow
  • Erroneous
  • Invalid
  • Logically Unsound

Unfortunately, many debaters have only a rudimentary knowledge of logical fallacies. In this post, we will examine Informal Fallacies. Duco A. Schneider, a psychologist, in his book Vision and Visual Perception: The Conscious Base of Seeing, defines an informal fallacy as “an argument whose stated premises fail to support its proposed conclusion.” In general, however, an informal fallacy is an argument that is fallacious for reasons other than structural or formal flaws. This post will be the first post in a series on the lies of rhetoric.

Disclaimer: Most of the examples of logical fallacies contained in this post relate to the NCFCA Team-Policy and Lincoln-Douglas resolutions this year because those resolutions are what are on my mind right now.

Ad Hominem

Making a personal attack at the opponent or a source.

1) Ad hominem abusive

Ad hominem abusive is a direct assault on a person. Politicians use ad hominems all the time. Example: “I never attacked him on his looks, and believe me, there’s plenty of subject matter there.”

2) Ad hominem circumstantial

Ad hominem circumstantial is an assault on a person’s background or circumstances. Example: “Professor Xi’s analysis on US policy towards China is not to be trusted because he was born in China.”

3) Tu quoque

Tu Quoque is a type of ad hominem that discredits the opponent’s claim by stating the opponent’s past actions are inconsistent with their belief. Example: “My opponent stated Chinese goods are harmful to America’s employment. However, they have purchased Chinese goods before. Clearly, their argument is unfounded.”

4) Poisoning the well

Poisoning the well is a preemptive ad hominem. This is when ad hominem information is presented before the source or person is even presented, to try to preempt the use of such a source. This is rare, but can used as a form of “persuasive inoculation.”

5) Genetic Fallacy

The genetic fallacy is an ad hominem attack on the place where the argument came from. Example: “The Electoral College was created by slaveowners; therefore, the Electoral College is immoral and should be abolished.”

Caveat: When is an ad hominem on a source justified?

Caveat: While many ad hominems are not legitimate, if a source (not your opponent!) demonstrates low trustworthiness or credibility, then that’s a valid point to undermine what they are using him to support. This raises the following question: When is an “ad hominem” on a source justified? The following two criteria can provide a basic framework for determining when an ad hominem attack on a source is justified. If both criteria are met, chances are an ad hominem attack would be legitimate.

Criterion 1. The author’s statement is opinionated rather than a factual claim or is making a factual claim that is demonstrably false. In other words, if you question whether or not the source is telling the truth (factually).

Criterion 2. The author personally benefits to state their position. However, this is rarely applicable in a debate round.


Amphiboly is an argument that uses bad grammar to support the conclusion. For example, ignoring a comma in a sentence to misconstrue numbers. This fallacy might not be intentional.

Appeal to Fear

Evokes fear in the audience’s mind to support the conclusion, even when the premise doesn’t lead to the conclusion. Example: “China has nuclear weapons and could easily take out the entire US Western seaboard in a mere couple of hours. Thus, sanction China.”

Caveat: Using pathos – putting the audience in the right frame of mind is part of rhetoric and is definitely recommended. If you use pathos while proving the conclusion, the pathos will not be an appeal to fear.

Appeal to the People

Appeal to the People fallaciously justifies the merit of an idea based on what the people think of the idea.

Caveat: If someone impacts popular opinion, then appealing to the people can be a legitimate argument. Oftentimes, what the public thinks about a policy is important. Example: “Because 99% of Americans are strongly against the Affirmative team’s proposal, their policy would result in a reduction of trust in government, a reduction in political capital, and a reduction in the capacity to pass beneficial policies in the future.”

1) Bandwagon

“Everybody’s using deodorant. Therefore, I should too.” more often: “every other country is doing this policy, therefore, we should do.” This is a fallacy unless the benefits of the idea are demonstrated in the areas where it is popular.

2) Appeal to Vanity

Appeals to the vanity, pride, or self-esteem of the person to persuade them to make an action. Example: read the Aesop fable of the Fox & the Crow.

3) Appeal to Snobbery

Usually used in the arena of marketing and advertising, the appeal to snobbery in a person in order to (usually) get them to buy a product.

4) Appeal to Tradition

Uses tradition as to prove the premise to the conclusion. Example: “We’ve always had the Electoral College. Thus, we should uphold tradition and keep it.” This is a fallacy unless the importance of tradition is demonstrated.

5) Appeal to Pity

The appeal to pity fallacy fallaciously substitutes the feeling for pity for a link between the premise and the conclusion. Example: “Retribution is unjust because of all the criminals who would be locked up in jail. Just think about how you would feel if you were locked in a single, cold, metal room for the rest of your life.”

Appeal to Unqualified Authority

Here are the three main types of Appeal to Unqualified Authority.

1) Different subject area of expertise

I have seen debaters use a rocket scientist as a source of authority on election law. Rocket scientists may be smart, but they are not omniscient. Appeal to Unqualified Authority is the fallacious assumption that because someone is an expert in one subject area, they are automatically an expert in another subject area.

2) No Warrant

Said expert provided no warrant (reason) for why their claim is true. Example: “Dr. Jones stated, ‘the US will go to war with China.’” (No warrant provided)

3) No credentials

No credentials were given to demonstrate the expert really was an expert.

Argumentum ad nauseam

Repeating an argument “ad nauseum” (Latin for ‘to the point of nauseum’) or so many times until the audience becomes tired of it.

Argument from ignorance

Argument from ignorance is the fallacy that a claim is true just because there’s no evidence or proof to the contrary. This is very prevalent in debate leagues. This is virtually the same as “Demanding Negative Proof,” which attempts to avoid proving some claim by demanding proof to the contrary.


  • “There is no proof that the Illuminati doesn’t exist. Illuminati confirmed.”
  • “There is no proof that God exists. Therefore, God does not exist.”
  • “There was no evidence provided by the Negative team that our plan wouldn’t work. Thus, we can conclude that our plan would work.”

(The reason why the last one is flawed is because the Affirmative team has the presumption of the “burden of proof” to demonstrate why their plan will work.)

Duco O. Schneider explains why the argument from ignorance is flawed:

“Arguments that appeal to ignorance rely merely on the fact that the veracity of the proposition is not disproved to arrive at a definite conclusion. These arguments fail to appreciate that the limits of one’s understanding or certainty do not change what is true. They do not inform upon reality. That is, whatever the reality is, it does not “wait” upon human logic or analysis to be formulated. Reality exists at all times, and it exists independently of what is in the mind of anyone. And the true thrust of science and rational analysis is to separate preconceived notions of what reality is, and to be open at all times to the observation of nature as it behaves, so as truly to discover reality. This fallacy can be very convincing”.

Put simply, the truth is independent of our perception of the truth. Therefore, the absence of proof for something does not prove its opposite.

Argument to Moderation

Other names: middle ground fallacy, false compromise, gray fallacy, and the golden mean fallacy. The Argument to Moderation fallaciously asserts that the truth must be a compromise between two extremes. Example: the Affirmative speaker in NCFCA’s LD resolution this year: “we can value both rehabilitation and retribution.”

Circular Reasoning

Circular reasoning fallaciously presumes to be true what is trying to be proven. It says X is true because of Y, and Y is true because of X. This video comically captures an example of circular reasoning.

Continuum Fallacy

Also known as the Fallacy of the Beard. This fallacy fallaciously says that two conditions cannot be distinct because there is no measurable, concrete intermediate states between them.

Example: “Why does the law state that you have to be 21 years old to drink?  Does it really make any difference if you are 20 years and 364 days old?  That is absurd.  Therefore if a single day makes no difference, then a collection of 1095 single days won’t make any difference, therefore, changing the drinking age to 18 will not make any difference.”

The continuum fallacy is a fallacy because a lack of a distinguishable medium does not prove two things are not distinct.


Equivocation is the confusing use of a term that has more than one meaning. This is rare in debate, but something to watch out for.

Fallacy of Causation

1) Post hoc ergo propter hoc

Post hoc ergo propter hoc is Latin for: “because X preceded Y, X must have caused Y.” Other names: Correlation implies Causation, Fallacy of False Cause, Fallacy of the single cause. You often hear politicians say that “under their tenure, X amount of jobs were created.” Technically, however, that is a fallacy unless they demonstrate how their policies was solely responsible for any ensuing gains in prosperity.

Examples that illustrate the absurdity of post hoc:

  • Significant correlation between ice cream sales and drowning deaths. Does that mean ice cream sales cause drowning?
  • The rooster crows before the sunrise. Does that mean the rooster causes the sunrise?
  • Significance statistical correlation between stork populations and human birth rates. Does that prove storks deliver babies?

Ways to respond to post hoc:

  1. Regression fallacy. Post hoc does not take into account natural fluctuations in Y and subsequently wrongly asserts causation.
  2. The responses to other fallacies of causation, as outlined below.

2) Non causa pro causa

Also known as the “wrong direction fallacy” or “reverse causality.” Non causa pro causa mistakes the cause for effect; instead of X causing Y, non causa pro causa says Y caused X.

3) Oversimplified cause

Also known as the fallacy of the simple cause, the oversimplified cause mistakenly says there were many factors causing Y, not just X. Example: “Europe has loser pays and also has less abusive lawsuits,” when in reality Europe also has a different legal system and a less litigious culture than helps reduce abusive lawsuits. The way to avoid committing the fallacy of oversimplified cause it take into account other factors, and still arrive at the same conclusion. The way to respond to the fallacy of oversimplified cause is that of “join effect.” There were really other things besides “X” which caused “Y.” This is especially useful when discussing economic effects or crime rate changes.

4) Common Cause

Common cause says that X causes Y, when in reality they have the same root cause.. The response to common cause is what is known as “endogeneity.” Endogeneity says that the root cause of X is the root cause of Y. Therefore, a correlation between the two does not prove causation. For example, one could say, “in Norway, where there is rehabilitation, recidivism rates are low. Therefore, rehabilitation reduces crime.” Using endogeneity as the response would say, “The cultural factors that caused rehabilitation in Norway, such as a homogeneous society, also reduce crime. Therefore, the rehabilitation is not what really reduced crime.”

The common cause fallacy is very similar to oversimplified cause fallacy, but not identical.  The different between the two comes from the fact that common cause ignores that the same factor that caused Y (like lower crime rates) also caused X (like rehabilitation), while oversimplified cause simply falsely assumes there is only one factor.

5) Gambler’s fallacy

The Gambler’s fallacy fallaciously asserts that if a particular action happens more or less frequently than chance would predict in the past, than the chances of happening in the future are likewise skewed, regardless of mathematical probability. The most obvious example of this is flipping a coin. Say someone flipped a coin 10 times and each time it landed on “tails.” Landing on tails 10 times in a row would indicate a propensity towards landing on the tails side. However, if you flip the coin again, there is still only a 50% chance of it landing on “tails” (unless there was something unusual with the coin). Another example: “because Taiwan was able to afford arm sales in the past, Taiwan will be able to afford arm sales right now.”

Caveat: The Gambler’s fallacy is only a fallacy when it applies to situations that can be predicted objectively with mathematical precision, such as flipping a coin.

Fallacy of many questions

A question that presupposes something that either has not been proven or agreed to by both sides. I have heard someone ask in CX before: “Why are you misconstruing my evidence?” Whether or not evidence was misconstrued, asking that question was fallacious – it’s a loaded question. Debaters often get around the fallacy of many questions by asking “Suppose insert hypothetical situation, would you agree that insert either horrible or highly desirable situation would occur?” Make sure to respond by mentioning its loaded question, and then proceed to answer it in a reasonable manner.

The fallacy of many questions is also known as the loaded question fallacy, complex question fallacy, the fallacy of presupposition, begging the question and plurium interrogationum.

False Attribution

When an advocate refers to a fallacious source to support the argument (similar to appeal to unqualified authority).

Historian’s Fallacy

“Hindsight is 20/20.” Historian’s fallacy is the fallacious assumption that those in the past viewed events from the same perspective and having the same information as those subsequently analyzing the decision. For example, the Supreme Court judges whether or not police officer shootings of civilians are justified on what the officer “reasonably” believed at the time. If the Supreme Court reversed this doctrine, it would be assuming policer officers had the same information as those reviewing the incident do.

Incomplete Comparison

Incomplete comparison is the fallacious comparison where not enough information is provided to make a complete comparison. This happens all the time in debate. The best way to respond to an incomplete comparison is

  1. Known the subject matter thoroughly beforehand.
  2. Think about what differences there between the two things being compared.

Inconsistent Comparison

Inconsistent comparison is where different methods of comparison are used. This often uses with evidence standards. Debaters commit the fallacy of inconsistent comparison when they hold the opposing team to a higher standard  – in terms of what evidence should be accepted – than themselves.

No Correlation

The no correlation fallacy is the opposite of post hoc. No correlation fallaciously asserts because there is no correlation between X and Y, X must not cause Y. The reason this is fallacious is that if there are many things that can influence Y (as is the case in most situations), the impact of X must be isolated in order to know X’s impact on Y, as is done in “regression analysis.” When economists evaluate the effect a policy has on the economy, they isolate the policy instead of just examining whether the economy happened to improve or worsen after the policy was implemented.


Reification, also known as hypostatization, is the fallacy of treating an abstraction as if it were a concrete action or event. This isn’t as applicable in Team-Policy debate, but applies in Lincoln-Douglas where debaters often assume a value is a tangible process (ie, retribution automatically means throwing people in prison; rehabilitation automatically means letting the criminal go) instead of a value.

Special Pleading

The special pleading fallacy is also known as the “accident fallacy.” Special pleading fallaciously attempts to cite something as an exemption to a generally accepted rule or principle without providing a warrant that justifies the exemption.

Statistical Fallacies

1) Cherry picking Data

Also known as “suppressing evidence fallacy,” cherry picking data examines a small group of data that is unique to prove a general group.

2) Sample too Small

Unrepresentative scope because the sample is too small.

3) Non-Comparison

The Study doesn’t compare the results to areas in which the policy was not implemented, therefore it has no relevance because the alternative is unknown.

Questions to ask to probe for statistical fallacies:

  1. What is the sample size?
  2. How did the study assure random sampling?
  3. How large is the group the sample speaks for?
  4. Was there a control group?
  5. What methodology was used?
  6. What were the questions phrased like? What are some examples questions?
  7. Was a third factor, X, taken into account? (Provide a third possible factor)
  8. Where did the study obtain its data from?
  9. Who sponsored the study?

Suppressed evidence

An argument that redefines two mutually exclusive options so that one alternative encompasses the other, thus making one alternative impossible.

Weak analogy

The weak analogy is the faulty use of an analogy. Example: “No one objects to a physician looking up a difficult case in medical books. Why, then, shouldn’t students taking a difficult examination be permitted to use their textbooks?” (Source for example)

Analogies may be helpful to illustrate a point, but they do not prove its conclusion.


Joshua Anumolu is in his fourth year of speech and debate. Last year, he was blessed to place 6th at the NCFCA National Championship in Team Policy debate. For him, competitive debate is about learning how to communicate truth effectively. Every round he lost, was a round he learned from to become a better communicator. He believes true mastery of rhetoric is accomplished when one finds their own balance between ethos, pathos, and logos. He loves to use debate as a platform to inform the audience of issues he cares about.

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