Logical fallacies

[CabVet]

You know they are here, people commit logical fallacies all the time, so just that we are clear I will list the most common ones for fun, in the order I have seen them being posted.

Straw man – to create the illusion of having refuted a proposition by replacing it with a superficially similar yet unequivalent proposition (the "straw man"), and refuting it, without ever having actually refuted the original position.

Ad hominem – attacking the arguer instead of the argument.

Argument from ignorance (appeal to ignorance, argumentum ad ignorantiam) – assuming that a claim is true (or false) because it has not been proven false (true) or cannot be proven false (true).

Onus probandi – from Latin "onus probandi incumbit ei qui dicit, non ei qui negat" the burden of proof is on the person who makes the claim, not on the person who denies (or questions the claim). It is a particular case of the "argumentum ad ignorantiam" fallacy, here the burden is shifted on the person defending against the assertion.

Red herring – a speaker attempts to distract an audience by deviating from the topic at hand by introducing a separate argument which the speaker believes will be easier to speak to.

Equivocation – the misleading use of a term with more than one meaning (by glossing over which meaning is intended at a particular time).

Argumentum ad populum (appeal to belief, appeal to the majority, appeal to the people) – where a proposition is claimed to be true or good solely because many people believe it to be so.

Argument from silence (argumentum e silentio) – where the conclusion is based on the absence of evidence, rather than the existence of evidence.

Argument from fallacy – assumes that if an argument for some conclusion is fallacious, then the conclusion itself is false.

 

[HitchSlap]

What do you call the fallacy of ignoring all available evidence?

 

[serge546]

Creationism?

 

[Loudmouth]

What do you call the fallacy of ignoring all available evidence?

Fallacy of One-Sidedness:

Logical Fallacy: One-Sidedness

 

[Michael]

What do you call the fallacy of ignoring all available evidence?

Denial.

 

[HitchSlap]

Denial.

So it's not just a river in Egypt....



















badda bam.

 

[Wiccan_Child]

I quite like the Fallacy Fallacy, where you show a fallacy in a logical argument, and use that to conclude that the conclusion of the argument is itself false.

P concludes Q
P is fallacious
Therefore ¬Q

Deliciously, this can get recursive:

1) P concludes Q
2) P is fallacious
3) Therefore ¬Q
4) (3) is fallacious
5) Therefore Q

The Fallacy Fallacy Fallacy

 

[Lion Hearted Man]

I like how tons of people on this board think that using firm language to disagree with someone is an ad hominem. People cry wolf with ad hominem accusations so much, and don't seem to realize how ad hominems are actually constructed.

Saying "you're wrong" != ad hominem

/off soapbox

 

[Stoneghost]

I like how tons of people on this board think that using firm language to disagree with someone is an ad hominem. People cry wolf with ad hominem accusations so much, and don't seem to realize how ad hominems are actually constructed.

Saying "you're wrong" != ad hominem

/off soapbox

By extension there is a difference between, "I think you are wrong because you are not smart" and "you are wrong because you are not smart". For something to be a logical fallacy the statements must be without equivocation. That said I think we should all try to avoid quaisi ad hominems as well as technical ad hominems. An unqualified "you're wrong" or "you're stupid" will look like ad hominems to most people most of the time.

 

[Lion Hearted Man]

By extension there is a difference between, "I think you are wrong because you are not smart" and "you are wrong because you are not smart". For something to be a logical fallacy the statements must be without equivocation. That said I think we should all try to avoid quaisi ad hominems as well as technical ad hominems. An unqualified "you're wrong" or "you're stupid" will look like ad hominems to most people most of the time.

The problem is that people (especially the creationists on this board) tend round-up any quasi-ad hominem to actual ad hominem. I agree that they should be avoided. But it's almost like pulling out the race card at any instance where it is helpful in an argument.

 

[Stoneghost]

The problem is that people (especially the creationists on this board) tend round-up any quasi-ad hominem to actual ad hominem. I agree that they should be avoided. But it's almost like pulling out the race card at any instance where it is helpful in an argument.

I think that happens on most boards, it is a quality of internet topic boards. And it is so easy to slip in quasi ad hominems as you say. I find myself doing it a lot.

 

[Matelot]

I like how tons of people on this board think that using firm language to disagree with someone is an ad hominem.

Oh I see right through you. You don't like heavy, flabby people.

 

[RickG]

I have noticed quite often that when a creationist claims someone is using a logical fallacy, that the one they choose to describe it doesn't even come close to being correct.

 

[Tiberius]

Argument from silence (argumentum e silentio) – where the conclusion is based on the absence of evidence, rather than the existence of evidence.

Dad seems to like this one...

 

[CabVet]

Dad seems to like this one...

His entire existence revolves around it

 

[jayem]

There's a web site that has a page for each of several logical fallacies. There's an icon, a description, and an example (though the discussions are fairly superficial.) But whenever you see someone committing a logical fallacy in an online forum, you copy the appropriate page, and paste it in your reply. It's kinda cool.

Thou shalt not commit logical fallacies

 

[acropolis]

People cry 'strawman' and 'ad hominem' waaay more often than they actually occur. Did the person you're discussing with slightly misunderstand your poorly-worded post? STRAWMAAAAAN. Did he or she imply you might not be the most brilliant person alive among their logic-based arguments? AD HOOOOMINEEEEM

 

[Michael]

People cry 'strawman' and 'ad hominem' waaay more often than they actually occur. Did the person you're discussing with slightly misunderstand your poorly-worded post? STRAWMAAAAAN. Did he or she imply you might not be the most brilliant person alive among their logic-based arguments? AD HOOOOMINEEEEM

In fairness however, those are the two most commonly used fallacies in debate followed quite closely by the ever popular non sequitur.

 

[acropolis]

In fairness however, those are the two most commonly used fallacies in debate followed quite closely by the every popular non sequitur.

Still over- and misused

 

[CabVet]

Another one I almost forgot:

No true Scotsman is an informal logical fallacy, an ad hoc attempt to retain an unreasoned assertion. When faced with a counterexample to a universal claim, rather than denying the counterexample or rejecting the original universal claim, this fallacy modifies the subject of the assertion to exclude the specific case or others like it by rhetoric, without reference to any specific objective rule.