Logic Fallacies in Debating

[David]

This was originally posted by Straha in the Science, Logic, and Morality forum. I am putting this here in hopes that it will help others that are unfamiliar with some terms used in debating. ~ David


1. Straw Man argument(sometimes referred to as the false dilemma argument): This is where you make a false statement for the opposing side and then knock it down. "Evolutionists say that all life came from nothing and this violates the second law of thermodynamics."

2. Ad hominem(against the man) Fallacy: This is where you direct the argument directly against the opponent. "You are A mother F*cking faggot whose IQ is less then a canine crossbred with pubic lice."
This however is not the same as an attack against the man from the argument. "From what you previously said I gather you are either a Neo-Nazi or A communist"

3. Ad infinitum Fallacy (sometimes called the slippery slope): This is where you base your argument on a simple logical idea and extrapolate to an illogical idea from it. "Ice Cream has fat in it. Fat can lead to obesity and high cholesterol. Obesity and high cholesterol can lead to an increased risk of heart attack. A heart attack can kill you. Thus eating a single scoop of Ben and Jerry's ice cream will kill you."

4. False Analogy. This is where you take a set of facts and use an analogy to falsify them and to perform a miniature slippery slope at the same time. "Evolutionists say birds evolved from dinosaurs, dinosaurs are reptiles, alligators are reptiles, and thus Evolutionists must say Birds evolved from alligators."

5. Appeals to authority. This is where you base an entire argument on what someone else said. This is not, however, when you make your argument and use what someone else said as backup. "Scientist John Doe said that evolution is impossible, thus it must be impossible."

6. Misrepresentation of Facts. This is when you take established fact, and use it to illogically prove a point. "Since half of the population spends an above median amount of time on the computer we must be wasting our life’s away." Or "Since half of the Black population scored beneath the median IQ score they must be stupider than whites, and thus should be enslaved."

7. Generalization. This is where you take one example of a thing, and use it to say all things are like that. "Since one of my friends was a sci-fi geek and was fat, all sci-fi geeks must be fat."

8. Misuse of the burden of proof. This is when you command the other person to prove the point when it is you who has to prove the point. The burden of proof becomes yours when you make a statement that goes against the current scientific or other standard. For instance you would have the burden of proof if you said "evolution is wrong, God made the world in seven twenty-four hour days, and the big bang theory and evolution are made by Atheistic scientists who want to separate you from god." Whereas you would not have the burden of proof if you said. "Black Holes have been proven to exist."

9. Tautologies (Sometimes refered to as circular logic). This is when you use your statement to prove your statement. "God exists because The bible says so, The bible is true becuase it was written by God."

[Darth Wong]

It should be noted, however, that some of Straha's definitions are a bit off, or confused.

1. Straw Man argument(sometimes referred to as the false dilemma argument): This is where you make a false statement for the opposing side and then knock it down. "Evolutionists say that all life came from nothing and this violates the second law of thermodynamics."

The strawman and false dilemma are two different arguments. Strawman is a distortion of your enemy's position so you can knock it down more easily. For example, "evolution tells us that totally random chemical reactions can produce life" (hint: chemical reactions are not totally random).

False dilemma, on the other hand, is forcing your opponent to choose between two artificially defined possibilities, ignoring many other possibilities. For example, "how can you say that science has validity when scientists don't even know what's happening inside a quasar?" (hint: forces you to choose between "scientists know everything" and "science is invalid").

2. Ad hominem(against the man) Fallacy: This is where you direct the argument directly against the opponent. "You are A mother F*cking faggot whose IQ is less then a canine crossbred with pubic lice."
This however is not the same as an attack against the man from the argument. "From what you previously said I gather you are either a Neo-Nazi or A communist"

Strictly speaking, an insult is just bad form, although it is often regarded as an ad-hominem fallacy because it can serve as a distraction. Nevertheless, the true ad-hominem fallacy attempts to tie the validity of your opponent's argument to his personal credibility rather than its intrinsic merits. For example, "your claims regarding religion are obviously the result of personal anger, as we can see from <insert reference to past argument>." You can't show that something is wrong simply by attacking its author's credibility.

3. Ad infinitum Fallacy (sometimes called the slippery slope): This is where you base your argument on a simple logical idea and extrapolate to an illogical idea from it. "Ice Cream has fat in it. Fat can lead to obesity and high cholesterol. Obesity and high cholesterol can lead to an increased risk of heart attack. A heart attack can kill you. Thus eating a single scoop of Ben and Jerry's ice cream will kill you."

It should be noted that the slippery slope fallacy is a fallacy because you cannot show that A causes B, B causes C, C causes D, etc. If you CAN show all of those connections, then it is not a fallacy.

4. False Analogy. This is where you take a set of facts and use an analogy to falsify them and to perform a miniature slippery slope at the same time. "Evolutionists say birds evolved from dinosaurs, dinosaurs are reptiles, alligators are reptiles, and thus Evolutionists must say Birds evolved from alligators."

I'm not sure what he's talking about here. A false analogy is simply an analogy which does not apply to the situation in question (for example, the infamous and horrendously flawed "tornado going through a field of parts and constructing a functional jumbo jet" analogy for evolution theory). It has nothing to do with any "miniature slippery slope".

5. Appeals to authority. This is where you base an entire argument on what someone else said. This is not, however, when you make your argument and use what someone else said as backup. "Scientist John Doe said that evolution is impossible, thus it must be impossible."

There are many variations upon the appeal to authority, conditions and forms of use in which they can and cannot be used, etc. Appeals to authority could warrant many posts on their own.

6. Misrepresentation of Facts. This is when you take established fact, and use it to illogically prove a point. "Since half of the population spends an above median amount of time on the computer we must be wasting our lives away." Or "Since half of the Black population scored beneath the median IQ score they must be stupider than whites, and thus should be enslaved."

That's more of a "leap in logic" fallacy; you say that A leads to B even though it does no such thing.

7. Generalization. This is where you take one example of a thing, and use it to say all things are like that. "Since one of my friends was a sci-fi geek and was fat, all sci-fi geeks must be fat."

Usually referred to as the "hasty generalization".

8. Misuse of the burden of proof. This is when you command the other person to prove the point when it is you who has to prove the point. The burden of proof becomes yours when you make a statement that goes against the current scientific or other standard. For instance you would have the burden of proof if you said "evolution is wrong, God made the world in seven twenty-four hour days, and the big bang theory and evolution are made by Atheistic scientists who want to separate you from god." Whereas you would not have the burden of proof if you said. "Black Holes have been proven to exist."

The burden of proof is always upon the person who tries to claim that some phenomenon exists. In the case of widely accepted scientific phenomena, it has been satisfied so many times by others that one is not normally expected to satisfy that burden of proof himself.

9. Tautologies (Sometimes refered to as circular logic). This is when you use your statement to prove your statement. "God exists because The bible says so, The bible is true becuase it was written by God."

Actually, a tautology and circular logic are not necessarily the same thing. A tautology is a trivial statement which is always true no matter what the input variables are. For example, "Either there's a God, or there isn't", or "even if you can produce evidence of transitional species, you can't prove that God didn't put it there on purpose, to make us think there were transitional species".

Circular logic is a form of tautology in which there are no input variables at all; the conclusion and premise are basically the same, as in the example Straha gave.

[David]

Ah, thanks for clearing those up.

[David]

I posted this in the Politics forum, but it sums up everything said in a little more concise way.


Evidence Fallacies:

Slippery Slope- Arguing that one bad thing will result in many others.

Confusing fact with opinion- Asserting opinions as though they were facts, or discrediting facts as opinions.

Red Herring- Distracting readers with sensational, irrelevant material.

Myth of the Mean- Using an average to hide a problem.

Flawed statistical comparisons- Using percentage increases or decreases to distort reality.

Defective testimony- Quoting out of context or omitting a speakers credentials

Inappropriate Evidence- Using facts when examples are needed, or examples when facts are needed, or a intimidating list of authorities as a substitute for information.

Flawed Proofs:

Ad hominem- Attacking the person rather than the point.

Begging the question- Assuming as decided what has not actually been proven

Defective arguments:

Shaky principle- Basing a line of argument on an unsound assumption.

Omitted qualifiers- Confusing probability with certainty by asserting a conclusion without qualification.

Post Hoc- Assuming that because on event follows another, it was caused by it.

Non sequitur- Reasoning in which principles and observations are unrelated to each other or to the conclusion drawn~ just thinking of this one makes me want to go out and hunt a giraffe, lets see how many of you get that one

Hasty generalization- Drawing a conclusion basedon insufficient or nonrepresentative observations.

Faulty analogy- Comparing things that are dissimilar in some important way.

Persuasive Design Fallacies:

Either-or thinking- Framing choices so that readers think they have only two options.

Strawman- Belittling or trivializing arguments to defeat them easily.