Logical Fallacies

Definition of terms and explanation of concepts

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McCulloch
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Logical Fallacies

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Post by McCulloch »

Imagine my horror when I went to one of my favourite pages with a handy list of logical fallacies to get a 404 page not found error. So as a public service, I will list with examples a few logical fallacies. I am deeply indebted to Logic & Fallacies at infidels.org, Table of Fallacies by Bruce Thompson, Stephen's Guide to the Logical Fallacies by Stephen Downes and Logical Fallacies and the Art of Debate by Glen Whitman. The Nizkor Project has another excellent list of logical fallacies. Here are some more reference pages for logical fallacies, complements of ST88:
Logical Fallacies by Michael Wong and How to Answer Questions (Without Offending People) - a Mormon source (anyone see the ad hom?)
A few things to note.
  • Just because the logic is false, the assertion may still be true.
  • Just because the logic is correct, the assertion may be false. The premises may be false.
I will try to include blatant examples to illustrate each fallacy. I will probably fail at my attempts to provide balanced examples. Please forgive me.
Edited to add Nizkor Project and links from ST88 (thanks)
Last edited by McCulloch on Fri Nov 04, 2005 9:33 am, edited 1 time in total.
Examine everything carefully; hold fast to that which is good.
First Epistle to the Church of the Thessalonians
The truth will make you free.
Gospel of John

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Argumentum ad hominem

Post #2

Post by McCulloch »

Argumentum ad hominem literally means "argument directed at the man". They falsely assume that characteristics of the person responsible for an argument imply that the argument itself must have certain characteristics, or that the characteristics of the person responsible for the argument are relevant to the acceptability of the argument itself.

If you refuse to accept a statement, and justify your refusal by criticizing the person who made the statement, then you are guilty of abusive argumentum ad hominem. Another form of argumentum ad hominem is to try and persuade someone to accept a statement you make, by referring to that person's particular circumstances. This particular form of Argumentum ad Hominem, when you allege that someone is rationalizing a conclusion for selfish reasons, is also known as "poisoning the well."

Examples:
  • Bertrand Russell is wrong about the existence of God. He divorced his wife.
  • There are so many hypocrites in the church, they cannot be right about anything.
Examine everything carefully; hold fast to that which is good.
First Epistle to the Church of the Thessalonians
The truth will make you free.
Gospel of John

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False Dilemma

Post #3

Post by McCulloch »

False Dilemma
A limited number of options (usually two) is given, while in reality there are more options.

Examples:
  • Either support Meech Lake or Quebec will separate.
  • Lord, Liar or Lunatic
  • Pascal's wager
Examine everything carefully; hold fast to that which is good.
First Epistle to the Church of the Thessalonians
The truth will make you free.
Gospel of John

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Post #4

Post by ST88 »


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Ad Hominem v Personal Attack

Post #5

Post by McCulloch »

Ad Hominem and Personal Attacks are two (not mutually exclusive) things. Many Ad Hominem arguments are, in fact, personal attacks and some personal attacks include ad hominem arguments.

Ad hominem is a logical fallacy. By itself, an ad hominem is not against the rules. There are different types of ad hominem fallacies. They all share the characteristic that they concern themselves with the person responsible for the argument, rather than the argument itself. They falsely assume that characteristics of the person responsible for an argument imply that the argument itself must have certain characteristics, or that the characteristics of the person responsible for the argument are relevant to the acceptability of the argument itself.
  • Abusive - This type of ad hominim is not only a logical fallacy, but is rude and uncivil and against the rules of this forum. If someone makes this type of argument, please report it to a Moderator using the [!] or with a Private Message. Abusive fallacy is persuasive when we mistake the context of the argument for one in which the character or characteristics of the opponent do actually matter. A common way to attack an opponent, while appearing to attack the argument, is to attribute personal qualities to the argument, as in "That's a stupid argument!" Since arguments are not persons, they cannot literally be stupid (or intelligent). Saying "That's a stupid argument," really means, "Only a stupid person would offer such an argument," so this really is an Ad Hominem - Abusive, even though it appears to be directed at the argument rather than at the person. The best tactic when faced with an ad hominim - abusive is not to defend one's self and thus give implicit recognition to the fallicious argument, but to point out the fallacy and direct the debate back to the facts.
  • Circumstantial - The argument attacks a position by appealing to the vested interests of the people who hold the position. However, someone's argument is not neccessarily wrong just because the person has a vested interest in the issue. This fallacy persuades by mimicking our legitimate concerns over conflict of interest.
  • Damning With Faint Praise - The argument "attacks" a position by complimenting or praising the opponent or the opponent's argument. However, the praise is misdirected or unenthusiastic, suggesting that relevant, enthusiastic praise would be undeserved. Some common forms of faint praise might include calling an opponent's position "well intentioned," "a fine ideal," or "based on legitimate concerns." They might include saying that the opponent "makes some good points," or "shouldn't be blamed." Even true statements can be deceptive. Normally we offer the strongest, most enthusiastic praise we feel is justified. Offering weak or unenthusiastic praise suggests (without asserting) that no stronger praise is warranted.
  • Ex Concessis (Guilt By Association) - The argument attacks a position by pointing out that people who hold the position sometimes act in ways that could be construed as inconsistent with the position, or hold (or previously held) views that could be construed as inconsistent with the position, or associate with other people who act in such ways or hold such views.
  • Special Pleading - The argument defends a position by claiming that the opponent lacks the necessary perspective (experiences or credentials) to appreciate the position. This lack allegedly makes the opponent unqualified to critique the position.
  • Tu quoque - this form of attack on the person notes that a person does not practice what he preaches.
Examine everything carefully; hold fast to that which is good.
First Epistle to the Church of the Thessalonians
The truth will make you free.
Gospel of John

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Special Pleading

Post #6

Post by McCulloch »

Special Pleading aka Argumentum ad misericordiam aka Appeal to Pity
The fallacy is committed when someone appeals to pity for the sake of getting a conclusion accepted. For example:

"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."
Examine everything carefully; hold fast to that which is good.
First Epistle to the Church of the Thessalonians
The truth will make you free.
Gospel of John

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Appeal to Consequences of a Belief

Post #7

Post by McCulloch »

Adapted from The Nizkor Project
Appeal to Consequences of a Belief

AKA Wishful Thinking

The Appeal to the Consequences of a Belief is a fallacy that comes in the following patterns:
  1. X is true (or false) because if people did not accept X as being true (or false) then there would be negative consequences.
  2. X is true (or false) because accepting that X is true (or false) has positive consequences.
  3. I wish that X were true (or false), therefore X is true (or false). This is known as Wishful Thinking.
This line of "reasoning" is fallacious because the consequences of a belief have no bearing on whether the belief is true or false. For example, if someone were to say "If sixteen-headed purple unicorns don't exist, then I would be miserable, so they must exist" it would be clear that this would not be a good line of reasoning. It is important to note that the consequences in question are the consequences that stem from the belief. It is important to distinguish between a rational reason to believe (evidence) and a prudential reason to believe (motivation). A rational reason to believe is evidence that objectively and logically supports the claim. A prudential reason to believe is a reason to accept the belief because of some external factor (such as fear, a threat, or a benefit or harm that may stem from the belief) that is relevant to what a person values but is not relevant to the truth or falsity of the claim.

The nature of the fallacy is especially clear in the case of Wishful thinking. Obviously, merely wishing that something is true does not make it true. This fallacy differs from the Appeal to Belief fallacy in that the Appeal to Belief involves taking a claim that most people believe that X is true to be evidence for X being true.
Examples of Appeal to Consequences of a Belief
  1. God must exist! If God did not exist, then all basis for morality would be lost and the world would be a horrible place!
  2. It can never happen to me. If I believed it could, I could never sleep soundly at night.
  3. I acknowledge that I have no argument for the existence of God. However, I have a great desire for God to exist and for there to be an afterlife. Therefore I accept that God exists.
  4. Henry M. Morris, wrote, "Belief in special creation has a salutary influence on mankind, since it encourages responsible obedience to the Creator and considerate recognition of those who were created by Him." The Remarkable Birth of Planet Earth (Creation-Life Publishers, 1972), pp. vi-viii.
Examine everything carefully; hold fast to that which is good.
First Epistle to the Church of the Thessalonians
The truth will make you free.
Gospel of John

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Begging the question (petito principii)

Post #8

Post by McCulloch »

Begging the question (petito principii) (circular reasoning)

Begging the Question is a fallacy in which the premises include the claim that the conclusion is true or (directly or indirectly) assume that the conclusion is true. In arguing for a claim, the claim itself is already assumed in the premise. Any form of argument in which the conclusion occurs as one of the premises, or a chain of arguments in which the final conclusion is a premises of one of the earlier arguments in the chain. More generally, an argument begs the question when it assumes any controversial point not conceded by the other side.

This sort of "reasoning" is fallacious because simply assuming that the conclusion is true (directly or indirectly) in the premises does not constitute evidence for that conclusion. Obviously, simply assuming a claim is true does not serve as evidence for that claim. This is especially clear in particularly blatant cases: "X is true. The evidence for this claim is that X is true."

Examples:
  1. God exists because this is what the Bible says, and the Bible is reliable because it is the word of God.
  2. Miracles cannot happen, because they would be against the natural laws.
  3. The belief in democracy is universal. After all, everyone believes in democracy.
  4. Interviewer: "Your resume looks impressive but I need another reference."
    Bill: "Jill can give me a good reference."
    Interviewer: "Good. But how do I know that Jill is trustworthy?"
    Bill: "Certainly. I can vouch for her."
The phrase "begs the question" has come to be used by those ignorant of logical terminology to mean "raises the question" or "suggests the question", as in "that begs the question" followed by the question supposedly begged. The following headlines are examples:
  • Warm Weather Begs the Question: To Water or Not to Water Yard Plants [*Latest Internet Fracas Begs the Question: Who's Driving the Internet Bus?
  • Hot Holiday Begs Big Question: Can the Party Continue?
This is a confusing and incorrect usage which is apparently based upon a literal misreading of the phrase "begs the question". It should be avoided, and must be distinguished from its use to refer to the fallacy.
Examine everything carefully; hold fast to that which is good.
First Epistle to the Church of the Thessalonians
The truth will make you free.
Gospel of John

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Post #9

Post by marc9000 »

There seem to be many fallacy lists - many fallacies are common among them all, but there are variations. Here is another detailed list;

http://www.don-lindsay-archive.org/skep ... ml#emotive

I think the most significant one in this list is the "argument from emotive language".
using emotionally loaded words to sway the audience's sentiments instead of their minds. Many emotions can be useful: anger, spite, condescension, and so on.
That covers a lot of other, more specific ones, IMO. It's a commonly used one too.

The problem with the whole fallacy concept is that they need to be applied by a completely neutral, emotionless observer, and none really exist. Often, if two people are applying fallacies to the same debate, and there is only a minor variation in bias of the two people, one will determine that a fallacy has been committed, and the other will not.

For example, the slippery slope fallacy will be claimed far more often by "progressives" than by "conservatives", because arguments for the status quo are more fearful of slippery slope consequences. That's true concerning the legalization of marijuana-leads-to-the-legalization-of-heroin argument. It was true 35 years ago, when the banning of cigarette smoking on airline flights of two hours or less was becoming law. Anyone who predicted that this would lead to smoking bans of ALL airline flights, or lead to smoking bans in all public places in entire cities, would have been accused of committing the slippery slope fallacy, even though 35 years later we can clearly see that they were not.

Is the application of logical fallacies more valuable to the progressive debater than they are to the conservative debater? As a conservative, I believe they are. Am I wrong? :-k

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Post #10

Post by McCulloch »

The fallacy fallacy is where you conclude that a particular assertion is false simply because the person making the assertion has committed logical fallacies in reaching his conclusion. In pointing out that someone has made logical fallacies, all one can do is show that their conclusions are not valid based on the evidence and reasoning so far provided not that their conclusions are necessarily false.
Examine everything carefully; hold fast to that which is good.
First Epistle to the Church of the Thessalonians
The truth will make you free.
Gospel of John

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