Mastering Logical Fallacies

In this section we will cover the Ad Hominem fallacy in detail, including five common forms: Ad Hominem (Abusive), Ad Hominem (Circumstantial), Ad Hominem (Guilt by Association), Ad Hominem (Tu quoque), and Poisoning the Well.

By the end of this section you should be familiar with these fallacies and be able to recognize when they are committed, even if not by name.

Suggesting that the person who is making the argument is biased, or predisposed to take a particular stance, and therefore, the argument is necessarily invalid.

When the source is viewed negatively because of its association with another person or group who is already viewed negatively.

Claiming the argument is flawed by pointing out that the one making the argument is not acting consistently with the claims of the argument.

Attacking the person making the argument, rather than the argument itself, when the attack on the person is completely irrelevant to the argument the person is making.

To commit a preemptive ad hominem attack against an opponent.  That is, to prime the audience with adverse information about the opponent from the start, in an attempt to make your claim more acceptable, or discount the credibility of your opponent’s claim.

In this section we will cover the Appeal to Common Belief fallacy in detail, also known as: appeal to accepted belief, groupthink, appeal to widespread belief, appeal to the masses, appeal to belief, appeal to the majority, argument by consensus, consensus fallacy, authority of the many, bandwagon fallacy, argumentum ad numerum, appeal to the number, argumentum consensus gentium, appeal to the mob, appeal to the gallery, mob appeal, social conformance, value of community.

By the end of this section you should be familiar with this fallacy and be able to recognize when it's committed, even if not by name.

When the claim that most or many people in general or of a particular group accept a belief as true is presented as evidence for the claim. Accepting another person’s belief, or many people’s beliefs, without demanding evidence as to why that person accepts the belief, is lazy thinking and a dangerous way to accept information.

A large group's aggregated answers to questions involving quantity estimation, general world knowledge, and spatial reasoning has generally been found to be as good as, and often better than, the answer given by any of the individuals within the group.

In this section, we cover four fallacies that are directly related to religion: Appeal to Faith, Appeal to Heaven, Magical Thinking, and Spiritual Fallacy. It will be made clear that it is not faith, the belief in magic, Heaven, or a spiritual world that is fallacious—it is the reliance on these beliefs in place of reason in rational discourse that is fallacious.

By the end of this section, students will

• learn when faith becomes a problem in rational discourse
• learn why any person of any religion claiming to know the will of the gods is acting fallaciously
• learn that magical thinking is very common, when it helps and when it doesn't
• learn when spirituality can be a roadblock to reason

This is an abandonment of reason in an argument and a call to faith, usually when reason clearly leads to disproving the conclusion of an argument.  It is the assertion that one must have (the right kind of) faith in order to understand the argument.

Asserting the conclusion must be accepted because it is the “will of God” or “the will of the gods”.  In the mind of those committing the fallacy, and those allowing to pass as a valid reason, the will of God is not only knowable, but the person making the argument knows it, and no other reason is necessary.

Making causal connections or correlations between two events not based on logic or evidence, but primarily based on superstition.  Magical thinking often causes one to experience irrational fear of performing certain acts or having certain thoughts because they assume a correlation with their acts and threatening calamities.

Insisting that something meant to be literal is actually “spiritual” in as an explanation or justification for something that otherwise would not fit in an explanation.

In this section we will cover the Ambiguity Fallacy, Equivocation, and the Use-Mention Error in detail. These fallacies involve playing with language and not being clear.

By the end of this section you should be familiar with these fallacies and be able to recognize when they are committed, even if not by name.

English is complicated and people can take advantage of that fact to confuse others.

A few examples of equivocation are presented that can be seen used today.

Confusing the word used to describe a thing, with the thing itself.  To avoid this error, it is customary to put the word used to describe the thing in quotes.

In this section, we cover five fallacies that are directly related to authority: Anonymous Authority, Blind Authority, Just Because Fallacy, Appeal to Celebrity, and Appeal to Authority. We’ll take a detailed look at how you can know when calling on an authority is fallacious vs. rational.

By the end of this section, students will

• learn that "they" are usually full of crap
• learn how dangerous blindly following authority can be
• learn how celebrities persuade us even though they shouldn't
• learn when believing an authority is a helpful heuristic, and when it is not
• learn that rational thinkers don't say "just because"

Using an authority as evidence in your argument when the authority is not really an authority on the facts relevant to the argument.  As the audience, allowing an irrelevant authority to add credibility to the claim being made.

Accepting a claim of a celebrity based on his or her celebrity status, not on the strength of the argument.

When an unspecified source is used as evidence for the claim.  This is commonly indicated by phrases such as “They say that...”, “It has been said...”, “I heard that...”, “Studies show...”, or generalized groups such as, “scientists say...”  When we fail to specify a source of the authority, we can’t verify the source, thus the credibility of the argument.  Appeals to anonymous sources are more often than not, either a way to fabricate, exaggerate, or misrepresent “facts” in order to deceive others into accepting your claim.  At times, this deception is done subconsciously -- it might not always be deliberate.

Asserting that a proposition is true solely on the authority making the claim while extreme cases also ignore any counter evidence no matter how strong.  The authority could be parents, a coach, a boss, a military leader, or a divine authority.

Refusing to respond to give reasons or evidence for a claim by stating yourself as the ultimate authority in the matter.  This is usually indicated by the phrases, “just trust me”, “because I said so”, “you’ll see”, or “just because”.  The just because fallacy is not conducive to the goal of argumentation -- that is coming to a mutually agreeable solution.  Nor is it helpful in helping the other person understand why you are firm on your position. “Just because” is not a reason that speaks to the question itself; it is simply a deflection to authority (legitimate or not).

In this section, we cover six fallacies that are directly related to emotion: Appeal to Ridicule, Appeal to Pity, Appeal to Fear, Appeal to Emotion, Appeal to Desperation, and Appeal to Anger. We are both creatures of emotion and logic, and despite what some may want to believe, emotion is a very important part of our humanity. Reason alone cannot guide our actions, but emotions often get in the way. In this section we will discuss this important distinction.

By the end of this section, students will learn

• how pity should not guide reason
• emotion can be both a powerful ally and foe to reason
• desperate times may call for desperate measures, but not irrational ones
• how talking louder and with more anger does not make one more right
• how powerful fear can be in clouding our ability to reason

This is the general category of many fallacies that use emotion in place of reason in order to attempt to win the argument.  It is a type of manipulation used in place of valid logic.

Arguing that your conclusion, solution, or proposition is right based on the fact that something must be done, and your solution is "something."

When fear, not based on evidence or reason, is being used as the primary motivator to get others to accept an idea, proposition, or conclusion.

When the emotions of anger, hatred, or rage are substituted for evidence in an argument.

The attempt to distract from the truth of the conclusion by the use of pity.

In this section we will cover the Argument From Ignorance fallacy in detail, also known as: appeal to ignorance, absence of evidence, argument from personal astonishment [form of], argument from Incredulity [form of].

By the end of this section you should be familiar with this fallacy and be able to recognize when it is committed, even if not by name. You will have practice identifying this fallacy in real world contexts.

We will also answer the big question, is absence of evidence, evidence of absence?

The assumption of a conclusion or fact based primarily on lack of evidence to the contrary.  Usually best described by, “absence of evidence is not evidence of absence.”

There is an infinity of things we cannot prove -- the moon being filled with spare ribs is one of them.  Now you might expect that any “reasonable” person would know that the moon can’t be filled with spare ribs, but you would be expecting too much.  People make wild claims, and get away with them, simply on the fact that the converse cannot otherwise be proven.

Plausibility is essentially believably, and people believe things for all sorts of reasons, many of which are not rational.

In this section, we cover three fallacies that are related: Begging the Question, Circular Reasoning, and Complex Question Fallacy. Circularity is common, sometimes humorous, and some would argue it is also necessary. But it doesn't have to be fallacious.

By the end of this section, students will learn

• when circularity is fallacious and when it is not
• how to counter the "all reasoning is circular" argument
• how to identify the complex question
• why the loaded question tricks us
• the difference between begging the question and raising the question

A type of reasoning in which the proposition is supported by the premises, which is supported by the proposition, creating a circle in reasoning where no useful information is being shared.  This fallacy is often quite humorous.

Any form of argument where the conclusion is assumed in one of the premises.  Many people use the phrase “begging the question” incorrectly when they use it to mean, “prompts one to ask the question”.  That is NOT the correct usage. Begging the question is a form of circular reasoning.

A question that has a presupposition built in, which implies something but protects the one asking the question from accusations of false claims.  It is a form of misleading discourse, and it is a fallacy when the audience does not detect the assumed information implicit in the question, and accepts it as a fact.

In this section, we cover seven fallacies that are related by the use and abuse of statistics: Multiple Comparisons Fallacy, Lying with Statistics, Ludic Fallacy, Hasty Generalization, Fake Precision, Biased Sample Fallacy, and Base Rate Fallacy. 

By the end of this section, students will learn

• how important it is to pay attention to a study's sampling method and size
• what statistical significance is
• how easily we are deceived by charts, graphs, and figures
• when common sense should trump statistics
• how exact numbers are deceiving
• that when something works "sometimes," it is often the equivalent of not working at all, due to probability alone

In inductive arguments, there is always a chance that the conclusion might be false, despite the truth of the premises.  This is often referred to as “confidence level”.  In any given study or poll, there is a confidence level of less than 100%.  If a confidence level is 95%, then one out of 20 similar studies will have a false conclusion.  If you make multiple comparisons, say 20 or more where there is a 95% confidence level, you are likely to get a false comparison.  This becomes a fallacy when that false comparison is seen as significant rather than a statistical probability.

Numbers don't lie, but them people who use them do.

Assuming flawless statistical models apply to situations where they actually don’t.  This can result in the over-confidence in probability theory or simply not knowing exactly where it applies as opposed to chaotic situations or situations with external influences too subtle or numerous to predict.

Drawing a conclusion based on a small sample size, rather than looking at statistics that are much more in line with the typical or average situation.

Using implausibly precise statistics to give the appearance of truth and certainty, or using negligible difference in data to draw incorrect inferences.

Drawing a conclusion about a population based on a sample that is biased, or chosen in order to make it appear the population on average is different than it actually is.