Logical Fallacies

Continuing our foray into the world of argument

Monty Python

What is Fallacy?

The art of the argument is thousands of years old, so too is the study of the faults of arguments called fallacies. They are flaws and faults that weaken arguments.

They try to persuade without providing legitimate grounds for accepting the conclusions.

Fallacious:...

People may commit them accidentally or use them deliberately to manipulate others.

Logical fallacies can be formal or informal.They are both arguments that sound persuasive but, fail to provide logical support for their conclusions.

Formal –...

Informal –...

A formal fallacy is one which involves an error in the form, arrangement or technical structure of an argument.

The question in view is not whether a conclusion is true or false, but whether the form of the argument is correct or incorrect — valid or invalid.

The concluding statement of an argument may be objectively true, though the argument is formally invalid; or the concluding statement may be objectively false, though the argument is formally valid. Here are some examples:

Formal Fallacy

Formally Valid Arguments:

1. True and Valid: All men are mortal.Socrates is a man.Therefore Socrates is mortal.

2. False but Valid: All men are green.Socrates is a man.Therefore Socrates is green.

In this example, the first statement is false, but the form or structure of the argument is correct or valid. (If all men were green; then Socrates would be also).

Formally Invalid Arguments:

3. False and Invalid: Some men are green.Socrates is a man.Therefore Socrates is green.

4. True but Invalid: Some men are mortal.Socrates is a man.Therefore Socrates is mortal.

In these examples, the first statement says something about some men, not about all men. One could correctly reason from this first statement that Socrates might possibly be green or mortal, but he could not correctly reason that Socrates necessarily is green or mortal.

As with most things philosophical, there is no common agreement on all aspects of argument faults, but types of mistakes made in informal arguments are usually grouped into these three broad areas:

1) .

2) .

3) .

Informal Fallacy

1) FALLACIES OF RELEVENCE

These are fallacies that introduceevidence to support an argument that really have no relationship to the argument: hence the evidence is irrelevant to the conclusion.

Here are some common fallacies of relevance:

This fallacy tries to counter an argument made by someone else by attacking that person, not the argument. Example:

“ So you think the Earth is round. What do you know? You're just a kid!“

No effort is made to address the argument made by 'the kid'. It instead attacks the kid. This type of argument can also be called poisoning the well, when you try to discredit someone before they have a chance to make their argument, and is often used in court to damage the reputation of a witness.

Attack on the Person

Appeal to IgnoranceDefinition: In the appeal to ignorance, the arguer basically says, "Look, there's no conclusive evidence on the issue at hand. Therefore, you should accept my conclusion on this issue."

Example: "People have been trying for centuries to prove that God exists. But no one has yet been able to prove it. Therefore, God does not exist."

Here's an opposing argument that commits the same fallacy:

"People have been trying for years to prove that God does not exist. But no one has yet been able to prove it. Therefore, God exists."

If most people believe something does that make it true? Not necessarily. Examples of this type of fallacy include:

"More people went to see this movie than any other, so it must be the best!“

“Everyone knows that the world is flat, so it must be flat"

Just because a lot of fools do something or believe in something doesn't make it so. It certainly doesn't make for a good argument. The classic refutation (comeback) for this one is:

If everyone went and jumped off the bridge, would you?"

Attack to Popularity

There are a variety of fallacies related to this one, which is based on the idea that an expert (an authority) knows something.

This is a tricky one, because sometimes evidence presented by an expert is more reliable than evidence presented by anyone else-for example, someone trained in auto repair probably knows more about auto repair than someone not so trained. On the other hand, some experts are not so expert:

Paris Hilton says that there is life on Mars, so there must be life on Mars, because she's famous and famous people know lots of things non-famous people don't.

Attack to Authority

This is a group of fallacies related to an argument that appeals to the emotions, rather than to reason. Examples include:

Scare tactic (fear):If you vote for him, he'll start a war!

Pity:I realize I'm not qualified, but if you don't give me this job, my children will starve!

Ridicule:That's a really dumb idea! Sure, like the world is round! What a buffoon!

Spite:I know you all hate her for being mean to you, so she doesn't deserve the award for best singer .

Appeal to Emotion

Red Herring

Definition: Partway through an argument, the arguer goes off on a tangent, raising a side issue that distracts the audience from what's really at stake. Often, the arguer never returns to the original issue.

Example: "Grading this exam on a curve would be the most fair thing to do. After all, classes go more smoothly when the students and the professor are getting along well." Let's try our premise-conclusion outlining to see what's wrong with this argument:

– Premise: Classes go more smoothly when the students and the professor are getting along well.

– Conclusion: Grading this exam on a curve would be the most fair thing to do.

When we lay it out this way, it's pretty obvious that the arguer went off on a tangent--the fact that something helps people get along doesn't necessarily make it more fair; fairness and justice sometimes require us to do things that cause conflict.

But the audience may feel like the issue of teachers and students agreeing is important and be distracted from the fact that the arguer has not given any evidence as to why a curve would be fair.

2) Fallacies of Ambiguity

These fallacies are often not deliberate, though they can be. They are misuses of language.

Two of the most common are:

.

These are errors related to grammaticalmisconstruction, which leads to a confusing conclusion, such as this traffic sign:

Slow children playing. This could mean:

a. Proceed slowly, as there are children playing here.

b. The children playing here are slow. In many cases, people familiar with the situation would be able to interpret the intended meaning.

Amphiboly can have serious consequences in legal documents, for example, in arguments over the interpretation of a phrase.

Amphiboly

This fallacy is perhaps the most simple and obvious of the fallacies of ambiguity. Here, a single term is used with two or more meanings in the same argument.

The term equivocation comes from the Latin - and means "with equal voice". When a term is used univocally in an argument, it always has the same meaning, but when it is used equivocally, more than one meaning is given equal voice.

Here is an amusing example of an argument using this fallacy:

Equivocation

It is well known that the average family has 2.5 children (premise #1). Well, Jane's family is very average (premise #2), so they must have2.5 children (conclusion).

The problem here is that the key term average is used in more than one sense. With the premise, the term is used in the sense of statistical averages. But the second premise switches to another sense of average, this time meaning not unusual.

By equating the two, the absurd conclusion of a family having fractional children is reached

3) Fallacies of Presumption...

They differ from fallacies of relevance in that the information may be relevant to the argument.

But it may be based upon an assumption that cannot be substantiated. These fallacies are more likely to involve errors of form than relevance or ambiguity fallacies.

Here are some common examples:

Hasty Generalization

Definition: Making assumptions about a whole group or range of cases based on a sample that is inadequate (usually because it is atypical or just too small).

Stereotypes about people ("frat boys are drunkards," "grad students are nerdy," etc.) are a common example of the principle underlying hasty generalization.

Example: "My roommate said her philosophy class was hard, and the one I'm in is hard, too. All philosophy classes must be hard!" Two people's experiences are, in this case, not enough on which to base a conclusion.

The scope of evidence (in context of course) is too small to support the conclusion.

Slippery Slope

Definition: The arguer claims that a sort of chain reaction, usually ending in some dire consequence, will take place, but there's really not enough evidence for that assumption.

The arguer asserts that if we take even one step onto the "slippery slope," we will end up sliding all the way to the bottom; he or she assumes we can't stop halfway down the hill.

Example: "Animal experimentation reduces our respect for life. If we don't respect life, we are likely to be more and more tolerant of violent acts like war and murder. Soon our society will become a battlefield in which everyone constantly fears for their lives.

It will be the end of civilization. To prevent this terrible consequence, we should make animal experimentation illegal right now."

Since animal experimentation has been legal for some time and civilization has not yet ended, it seems particularly clear that this chain of events won't necessarily take place.

These fallacies make connections between bits of evidence where connections are not really present. Using with this, therefore because of this ergo… mixes up only coincidentally related evidence and draws a relationship between them.

A causes B (without real proof that this causal relationship actually exists).This causal relationship is often claimed when there is correlation between A and B (that they vary together) or a relatively distant causal connection.

ExampleIt is dark now, which makes it very dangerous. It is not the dark that causes danger.

This can occur in medicine, where a set of symptoms can lead to an incorrect diagnosis of a disease or illness that is actually caused by something else.

False Cause

This fallacy "Occurs when a debater makes an argument urging the audience to accept, or condone, one thing that is wrong because another similar thing, also wrong, has been accepted and condoned For example:Speaker A: You shouldn't embezzle from your employer. It's against the law. Speaker B: My employer cheats on their taxes. That's against the law, too.

The unstated premise is that breaking the law (the wrong) is justified, as long as the other party also does so. It is often used as a red herring, or an attempt to change or distract from the issue.

Two Wrongs

Also called a loaded question, this fallacy involves posing a question in such a way that by either affirming or denying it implies agreeing to something controversial in the question. The classic example is:

Have you stopped beating your wife?

If you answer no, it implies that you are continuing this abhorrent practice and are not a nice person. If you answer yes, it means that, while you have now ceased this practice, you are admitting that you did it in the past. The question is complex, because it is actually lumping two questions into one.

Complex Question

This fallacy involves artificially narrowing the choices available and then demanding that someone pick from this limited selection of choices. This fallacy is also known as black-or-white of a false dichotomy (a dichotomy being a two-ness). The syllogistic form of the disjunction is often used to create the dilemma:

A or BNot ATherefore B.

The trick in rhetoric is to present only this clear choice and then to make the choice of A repugnant. An example from Canadian history was the 1935 Liberal election slogan "It's King or it's chaos!" which implied that if voters choose other than King, they would be voting for chaos. Of course this was not, strictly speaking, true.

False Dilemma

Article discussing election fallacies:

Top 10 Logical Fallacies in Politics -

Monty Burns Campaign - Simpsons