Logic Fallacy reference thread Mk. 2

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Logic Fallacy reference thread Mk. 2

Postby Darth Wong » 2003-12-14 07:39pm

This is our second attempt at a logical fallacy reference thread. The first thread was started with noble intentions, but ended up becoming just another discussion thread, which sort of defeats the purpose of a reference thread. If you have to wade through people asking questions, making clarifications to each others' posts, and arguing, you can hardly call it a reference.

In order to keep the same thing from happening here, some guidelines will be necessary. This thread should contain only high-quality descriptions of logical fallacies. Criteria for a high-quality description of a fallacy are:
  1. Gives an accurate definition of the fallacy (there are several websites such as http://www.datanation.com/fallacies/ and http://www.nizkor.org/features/fallacies/ and http://www.infidels.org/news/atheism/logic.html which can give you fairly detailed descriptions).
  2. Describes examples of the fallacy. There should ideally be two examples: one which is painfully obvious and one which is more realistic (meaning that one is actually likely to find it in use, and it's not that easy to spot. The goal of this thread should be to help people spot fallacies which are not that easy to spot. It is not to simply list all of the known fallacies; for that, we could simply link to one of the aforementioned online fallacy-discussion websites.
  3. Describes an actual fallacy rather than poor debating. Contrary to popular belief, outright lies are not logical fallacies; they are obviously bad, but not every bad debate technique is a fallacy. A fallacy is a logical argument (ie- takes the premise A and argues that if it is true, then conclusion B must also be true) which does not actually follow.

Entries in this thread which do not meet the criteria will be deleted and their authors viciously beaten with heavy wooden mallets. Corrections made to erroneous entries will be edited into the original entry with a credit given to the author, and then the corrective post will be deleted (this is to keep the thread clean). This thread is for informative purposes, and should not be for asking questions, spamming, bragging about nailing somebody for using a fallacy, half-assed fallacy definitions, etc.

An example of what we're looking for will follow (I recommend a single post for each fallacy, so they can be easily linked to).

One final note: one should keep in mind that it is a rare (perhaps mythical) person indeed who never commits a fallacy. But one can still differentiate between the argument which contains a fallacy and the argument which is almost entirely based on fallacies.
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"It's not evil for God to do it. Or for someone to do it at God's command."- Jonathan Boyd on baby-killing

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"Viagra commercials appear to save lives" - tharkûn on US health care.

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Postby Darth Wong » 2003-12-14 07:40pm

Strawman Fallacy

Definition
Misrepresents your opponent's argument so it is easier to attack. This allows you to knock down the distorted version (the "strawman") in order to make it seem as if you have knocked down your opponent's actual argument. It is a fallacy because it assumes that if you can disprove the strawman, you have also disproven your opponent's real, perhaps seemingly related argument. See http://www.nizkor.org/features/fallacies/straw-man.html

Example 1 (very obvious and abusive)
MARK: "If the gap between rich and poor is too great, you will have social problems".
DAVE: "Oh, I see. So you think we should become Communists, eh Comrade Lenin?"
MARK: "That's not what I said."
DAVE: "Oh right, maybe I should shut up before you SEND ME TO THE GULAG, eh Comrade?"

Example 2 (less obvious)
MARK: "If the gap between rich and poor is too great, you will have social problems."
DAVE: "Our Constitution guarantees equality of opportunity, not equality of outcome. Forced equality of outcome will create far more problems than it solves."

Notice how Dave converts "reduce the gap" to "forced equality".

Example 3 (subtle)
MARK: "Fifty years ago, marriage between blacks and whites was just as much of a violation of social tradition as gay marriage today, yet we now consider it a violation of human rights to ban racial intermarriage. Therefore, you can hardly appeal to social tradition in order to uphold a ban on gay marriage."
DAVE: "Race has nothing to do with sexual orientation. It's a completely false analogy."

Notice how Dave takes an argument intended to demonstrate the historical fluidity of social tradition and completely distorts it in order to act as though Mark is trying to say that race and sexual orientation are the same thing. This exact exchange can be found, almost verbatim, in most arguments about gay marriage; in fact, the general technique of taking an analogy and acting as though it claims to equate the situation to the analogy rather than demonstrate a point of logic is extremely common in all debates, and is a particularly dangerous evasive technique which you should carefully watch out for.

Example 4 (Science-related}
MARK: "Scientific theories are by far the best method we have of accurately describing the natural universe. Every other method deliberately incorporated either subjectivity, nonsense, or both."
DAVE: "Ah, but scientists can make mistakes. They're not infallible, so you should not appeal to their authority."

Notice how Dave takes a relative expression (that science is clearly superior to all other methods) and acts as though Mark is claiming scientists are infallible. This is also an example of the Black/White Fallacy.

More Tips: Most strawman fallacies fall into two categories: incomprehension and exaggeration. The first category characterizes virtually all creationist arguments: they almost never understand the scientific method, the scientific principles involved in the related areas of geology, astrophysics, thermodynamics, or biology, or even how the theory of evolution itself works, so they concoct all manner of arguments which look like this: "if evolution were true, <insert absurd prediction here>". It also tends to happen when people don't bother reading their opponents' arguments very thoroughly before answering (a common problem on the Internet, where answers are often fired off in the heat of anger without much thought). The second category is ubiquitous in political debates: it is actually quite rare to find a political debate where neither party exaggerates the other side's position (in fact, both sides usually do it). The third category of strawman fallacy is deliberate deception, but that is actually rare except when dealing with downright unprincipled opponents.
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"It's not evil for God to do it. Or for someone to do it at God's command."- Jonathan Boyd on baby-killing

"you guys are fascinated with the use of those "rules of logic" to the extent that you don't really want to discussus anything."- GC

"I do not believe Russian Roulette is a stupid act" - Embracer of Darkness

"Viagra commercials appear to save lives" - tharkûn on US health care.

http://www.stardestroyer.net/Mike/RantMode/Blurbs.html

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Postby The Dark » 2004-01-25 02:49am

Appeal to the People (Ad Populum)

Definition
Attempts to persuade an individual or group by appealing to the desire to belong to a particular group. It is a fallacy because the beliefs of a group do not alter the logic of an argument.

Example 1
Joe: I don't think going to war in Iraq was the right thing to do.
Bill: Joe, are you saying President Bush made a wrong decision when he decided to invade Iraq? That's not how Americans think. Not true Americans. You are an American, aren't you?

Example 2 (slightly more subtle)
Joe: I'm not really sure I want the expensive sports car. That sedan is cheaper and it gets better gas mileage.
Bill: Sure, but the sedan is so pedestrian. Only the elite buy the sports car. It shows that the owner has money and prestige.
Stanley Hauerwas wrote:[W]hy is it that no one is angry at the inequality of income in this country? I mean, the inequality of income is unbelievable. Unbelievable. Why isn’t that ever an issue of politics? Because you don’t live in a democracy. You live in a plutocracy. Money rules.


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Postby Rogue 9 » 2004-01-28 06:29pm

Protecting the Hypothesis

Well, I'm all sure we can think of a major example of this one. :wink: Protecting the hypothesis is twisting available evidence in any way possible in order to protect your original hypothesis, no matter what observation or experimentation yield.

Example 1
Joe: When Palpatine is hitting Vader with Force lightning, we see an X-ray like outline of Vader's skeleton. It shows that two of Vader's neck vertabrae are black, unlike the rest of the bone. This could possibly be caused by a metal vertabrae replacement. Star Wars medical technology must be advanced indeed!

Robert: We don't know that that isn't normally the case in Star Wars. It could be a natural growth.

:twisted:

Example 2
Jim: The turbolasers are multi-gigaton range. They could blast a GCS apart.
Paris: No, Picard said that lasers can't even break navigational deflectors, and turbolasers are just improved lasers. Even if a Star Destroyer got next to the Enterprise it couldn't touch it!
Jim: Picard said that about those particular lasers. It doesn't follow that Federation shields can block lasers of any strength.
Paris: Yes it does!
Jim: How?
Paris: I'm not listening!

(Okay, on second thought I'm not sure if that one really demonstrates this particular fallacy or not. :? Seems more like slippery slope now that I read it. And its definitely not subtle. Hmm.)

Example 3 (Slightly more subtle.)
John: Hyperdrive is much faster than warp. Hyperdrive equipped ships can span the galaxy in a few days.
Robert: The Star Wars galaxy must be much smaller than the Milky Way.

(Note how rather than proving that hyperdrive is not faster than warp, Robert attempts to change outside factors to make his argument look better.)

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Postby Bugsby » 2004-08-23 12:15am

Violation of Hume's Law

Hume's Law
An "ought" conclusion must be proven using at least one "ought" premise. An "ought" conclusion cannot be proven from an "is" premise.

Sample 1
"As the president, I weild supreme executive power. Therefore, you cannot question me."
-Because the president weilds power, he infers that he ought to weild his power. No good.

Sample 2
J. S. Mill: People desire happiness. Therefore, by definition, happiness is desirable. Desirable means that something ought to be desired. Therefore, people ought to desire happiness. Happiness is good.
-A subtle flip-flop using multiple definitions. Widely respected. Utterly wrong.

Sample 3
Increased spending will lead to a larger and more capable military, better able to defend our country. Therefore, we should increase spending.
-Leaves out the critical step of saying that "more military is good," a necessary premise for this argument to be valid.

MANY more examples of this. Just watch for "is" statements that lead towards an "ought" or a "should."
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Postby Rye » 2004-09-13 01:45pm

The Stolen Concept Fallacy

Thought this was a cool one.

from here

To understand this fallacy, consider an example of it in the realm of politics: Proudhon's famous declaration that "All property is theft."

"Theft" is a concept that logically and genetically depends on the antecedent concept of "rightfully owned property" — and refers to the act of taking that property without the owner's consent. If no property is rightfully owned, that is, if nothing is property, there can be no such concept as "theft." Thus, the statement "All property is theft" has an internal contradiction: to use the concept "theft" while denying the validity of the concept of "property," is to use "theft" as a concept to which one has no logical right — that is, as a stolen concept.

All of man's knowledge and all of his concepts have a hierarchical structure. The foundation or ultimate base of this structure is man's sensory perceptions; these are the starting points of his thinking. From these, man forms his first concepts and (ostensive) definitions — then goes on building the edifice of his knowledge by identifying and integrating new concepts on a wider and wider scale. It is a process of building one identification upon another — of deriving wider abstractions from previously known abstractions, or of breaking down wider abstractions into narrower classifications. Man's concepts are derived from and depend on earlier, more basic concepts, which serve as their genetic roots. For example, the concept "parent" is presupposed by the concept "orphan"; if one had not grasped the former, one could not arrive at the latter, nor could the latter be meaningful.

The hierarchical nature of man's knowledge implies an important principle that must guide man's reasoning: When one uses concepts, one must recognize their genetic roots, one must recognize that which they logically depend on and presuppose.

Failure to observe this principle — as in "All property is theft" — constitutes the fallacy of the stolen concept.

Now let us examine a few of the more prevalent anti-reason tenets and observe how they rest on this fallacy.

Consider the laws of logic. In the Aristotelian school of thought, these laws are recognized as being abstract formulations of self-evident truths, truths implicit in man's first perceptions of reality, implicit in the very concept of existence, of being qua being; these laws acknowledge the fact that to be, is to be something, that a thing is itself. Among many contemporary philosophers, it is fashionable to contest this view — and to assert that the axioms of logic are "arbitrary" or "hypothetical."

To declare that the axioms of logic are "arbitrary" is to ignore the context which gives rise to such a concept as the "arbitrary." An arbitrary idea is one accepted by chance, caprice or whim; it stands in contradistinction to an idea accepted for logical reasons, from which it is intended to be distinguished. The existence of such a concept as an "arbitrary" idea is made possible only by the existence of logically necessary ideas; the former is not a primary; it is genetically dependent on the latter. To maintain that logic is "arbitrary" is to divest the concept "arbitrary" of meaning.

To declare that the axioms of logic are "hypothetical" (or merely "probable") is to be guilty of the same contradiction. The concept of the "hypothetical (or the "probable") is not a primary; it acquires meaning only in contradistinction to the known, the certain, the logically established. Only when one knows something which is certain, can one arrive at the idea of that which is not; and only logic can separate the latter from the former.

"An axiom is a statement that identifies the base of knowledge and of any further statement pertaining to that knowledge, a statement necessarily contained in all others, whether any particular speaker chooses to identify it or not. An axiom is a proposition that defeats its opponents by the fact that they have to accept it and use it in the process of any attempt to deny it. Let the caveman who does not choose to accept the axiom of identity, try to present his theory without using the concept of identity or any concept derived from it..." (Atlas Shrugged).

When neo-mystics challenge the concept of "entity" and announce that "naive" reason notwithstanding, all that exists is change and motion — ("There is no logical impossibility in walking occurring as an isolated phenomenon, not forming part of any such series as we call a 'person,'" writes Bertrand Russell) — they are sweeping aside the fact that only the existence of entities makes the concepts "change" and "motion" possible; that "change" and "motion" presuppose entities which change and move; and that the man who proposes to dispense with the concept of "entity" loses his logical right to the concepts of "change" and "motion": having dropped their genetic root, he no longer has any way to make them meaningful and intelligible.

When neo-mystics assert that man perceives, not objective reality, but only an illusion or mere appearance — they evade the question of how one acquires such a concept as "illusion" or "appearance" without the existence of that which is not an illusion or mere appearance. If there were no objective perceptions of reality, from which "illusions" and "appearances" are intended to be distinguished, the latter concepts would be unintelligible.

When neo-mystics declare that man can never know the facts of reality, they are declaring that man is not conscious. If man cannot know the facts of reality, he cannot know anything — because there is nothing else to know. If he cannot perceive existence, he cannot perceive anything — because there is nothing else to perceive. To know nothing and to perceive nothing is to be unconscious. But to arrive — by a complex chain of "reasoning" and a long string of such concepts as "knowledge," "perceive, "evidence," "infer," "proof" — at the conclusion that one is not conscious, is scarcely epistemologically admissible.

"'We know that we know nothing,' they chatter, blanking out the fact that they are claiming knowledge — 'There are no absolutes,' they chatter, blanking out the fact that they are uttering an absolute — 'You cannot prove that you exist or that you're conscious,' they chatter, blanking out the fact that proof presupposes existence, consciousness and a complex chain of knowledge: the existence of something to know, of a consciousness able to know it, and of a knowledge that has learned to distinguish between such concepts as the proved and the unproved." (Atlas Shrugged)

Existence exists (that which is, is) and consciousness is conscious (man is able to perceive reality) — these are axioms at the base of all of man's knowledge and concepts. When neo-mystics contest or deny them, all of the concepts they use thereafter are stolen. They are entitled only to such concepts as they can derive from non-existence by means of unconsciousness.

It is rational to ask: "How does man achieve knowledge?" It is not rational to ask: "Can man achieve knowledge?" — because the ability to ask the question presupposes a knowledge of man and of the nature of knowledge. It is rational to ask: "What exists?" It is not rational to ask: "Does anything exist?" — because the first thing one would have to evade is the existence of the question and of being who is there to ask it. It is rational to ask: "How do the senses enable man to perceive reality?" It is not rational to ask: "Do the senses enable man to perceive reality?" — because if they do not, by what means did the speaker acquire his knowledge of the senses, of perception, of man and of reality?

One of the most grotesque instances of the stolen concept fallacy may be observed in the prevalent claim — made by neo-mystics and old-fashioned mystics alike — that the acceptance of reason rests ultimately on "an act of faith."

Reason is the faculty that identifies and integrates the material provided by the senses. Faith is the acceptance of ideas or allegations without sensory evidence or rational demonstration. "Faith in reason" is a contradiction in terms. "Faith" is a concept that possesses meaning only in contradistinction to reason. The concept of "faith" cannot antecede reason, it cannot provide the grounds for the acceptance of reason — it is the revolt against reason.

One will search in vain for a single instance of an attack on reason, on the senses, on the ontological status of the laws of logic, on the cognitive efficacy of man's mind, that does not rest on the fallacy of the stolen concept.

The fallacy consists of the act of using a concept while ignoring, contradicting or denying the validity of the concepts on which it logically and genetically depends.
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Postby Lucifer » 2005-02-01 01:58am

Ad Hominem

(from Latin, (of attack) "to, towards the person")
An attack on the person instead of the argument itself. It's not ad hominem unless an argument is involved.

Example 1

Smith: Give me evidence that the Earth is older than 6000 years.
Doe: The fossil record is accurate and continuous. It dates beyond a few million years.
Smith: How would you know? You're not a paleontologist. Therefore, your claim is not reliable.

Example 2

Smith: Evolution doesn't have any morals.
Doe: That doesn't make it false.
Smith: That's because you don't read the bible, so you don't know what a moral is.

(Smith is attacking Doe's knowledge and assuming he personally doesn't read the bible.)

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Fallacy: Missing Negative Cases

Postby Nick Lancaster » 2005-02-22 07:47pm

Missing Negative Cases

The argument is based on selected data which supports the claimant's theory and ignores examples to the contrary.

Example 1

Jim: Crop circles are the work of extraterrestrial forces.
Darth: There was a case where teenagers made crop circles near Vacaville, California, and demonstrated, on camera, how they did it.

Jim based his assumption on the absence of observed human activity. Yet, if you were going to create a crop circle to mystify people, would you do it in full daylight where you could be observed? Why is it acceptable to believe in unseen extraterrestrials and not humans acting covertly?

Example 2
Jean-Luc: We'll beam a torpedo into your engine room!
Darth: If this tactic is sound, why was it not used against the Borg, the Jem Ha'dar, the Cardassians, and the Romulans? Given that these races also have transporter technology, why didn't they use it against the Federation?

Jean-Luc is trying to establish his tactic as practical/effective, even though it is not widely used by the Federation or its enemies.

Example 3

Will: The Empire are lousy shots, anyway.
Darth: I seem to recall a number of dead Rebel Troopers at the beginning of Episode IV, quite a few dead Rebels on Hoth in Episode V, and Princess Leia gets clipped on the arm while firing from cover in Episode VI.

Will is trying to support his claim based only on those instances where stormtroopers are seen to fire and yet leave the heroes untouched.

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Postby DaveJB » 2005-02-25 06:56pm

Appeal to Motive

Attempting to dismiss an argument on the grounds that the person advancing it is doing so due to an ulterior motive, not because it's the most logical position. Technically it's a type of Ad Hominem attack, but it's one of the more common subtypes.

Example 1 - Not that obvious

Jim: Have you read Dr. Johnson's paper about his theory that literal biblical creation is true?
Tim: No point, it'll all be wrong. He comes from a devoutly religious background, so his method and conclusions are going to be biased.

(Tim's point may seem valid, but he's dismissing the paper as inaccurate purely on the writer's background. While what he is saying about the paper has proven true about similar theories in the past, the fact remains that he is appealing to the writer's motives, rather than actually reading the paper and evaluating it.)

Example 2 - Pretty obvious

Freddy: I recommend AMD processors to my friends because most of them play a lot of games, and the Athlon 64 is the best processor for games.
Jason: And not because you own AMD stock? You're just concerned with getting a bigger dividend for yourself aren't you?
Freddy: Check the hardware websites. Just about all of them show the Athlon 64 performing better than the Pentium 4.
Jason: Only because all their readers like AMD! If they showed the Pentium 4 beating the Athlon 64 like it really does, the AMD fans wouldn't read the websites and they'd lose out on a load of advert money.

(No less than three Appeals to Motive by Jason in this example! First by accusing Freddy of recommending AMD processors purely because of his ownership of AMD shares, then accusing the hardware sites of only showing the results they do to keep their AMD-supporting readers happy, and finally by saying that AMD fans only read the hardware websites because they show AMD processors beating their Intel counterparts.)

Example 3 - Extremely obvious

Mike: I'm tired of your bullshit, Bob. Debate me now or I'll ban you.
Bob: Thanks for proving what I've been saying all along! You're afraid of my arguments, you know that they're right. So, you threaten to ban me unless I submit to your fallacy polluted, lie-strewn, inherently biased debate. What a coward you are, not having the balls to admit why you really want to ban me. You disgust me.

(Doesn't really need an explanation, does it?)

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Postby Rogue 9 » 2005-08-22 01:40pm

Reductio ad Hitlerum

Bearing a name derived from the reductio ad absurdum logical argument and closely related to Godwin's Law, this fallacy is that of arguing that any concept, idea, or action supported by Hitler or the Nazi Party is therefore evil or morally wrong.

Example 1
Ted: Vegetarianism is a better, healthier, and moral way of life.
Fred: But Hitler was a vegetarian! Vegetarianism = Nazism!

(Obviously, vegetarianism is not immoral simply because Adolf Hitler was a vegetarian. I'll try for a more subtle example, but since the fallacy is by nature so blatantly obvious, it won't be very much so.)

Example 2
Bob: Corporations are out of control. The government should put the industrialists on a leash before this gets any worse.
Tom: The Nazi Party incorporated and controlled German industrialists, Bob. Are you sure you want to set up that situation again?

(The above not only utilizes reductio ad Hitlerum, but also appeals to consequences in an oblique fashion, thus becoming doubly fallacious yet far more effective against an inattentive opponent.)
Last edited by Rogue 9 on 2008-02-06 04:33pm, edited 1 time in total.
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Rejection by the Trivial Omission

Postby kaikatsu » 2005-08-30 03:16pm

Rejection due to Incompleteness / Trivial Omission

This is an argument that rejects any theory that does not explain every possible element, even when those elements have little to no bearing on the argument.

Example One Obvious
Your theory of gravity cannot be correct because it does not explain why we have no unicorns.

Example Two Annoying
You have not been able to demonstrate what TurboLasers actually are, so why should I believe that they aren't like ordinary lasers lasers?

Example Three Subtle
The theory of evolution has not been able to demonstrate nearly as many transitional fossils as Darwin predicted. As such it must be false.

This type of argument shows up a lot during heated debates because it is based on the assumption that if ONE omission or error can be shown in a broad argument, the ENTIRE argument can be ignored. This is in many ways related to the black and white falicy.

Naturally, if incompleteness of an argument can be demonstrated, the next -logical- question is "how does this affect the argument as a whole" rather than total rejection.

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Postby SVPD » 2006-03-02 12:27am

Slippery Slope

from Wikipedia

The slippery-slope argument occurs in the following context: A, B denote events, situations, policies, actions etc. Within this context, the proposer posits the following inferential scheme:

If A occurs
then the chances increase that B will occur
The argument takes on one of various semantical forms:

In one form, the proposer suggests that by making a move in a particular direction, we start down a "slippery slope". Having started down the metaphorical slope, it appears likely that we will continue in the same direction (the arguer usually sees the direction as a negative direction; hence the "sliding downwards" metaphor).
Another form appears more static, arguing that admitting or permitting A leads to admitting or permitting B, by following a long chain of logical relationships.


The slippery slope fallacy can be hard to deal with for 2 reasons:

1. If event a in a sequence actually causes event b which causes event c and so forth, it's not fallacious. For example, it would not be fallacious to say that flying an airliner loaded with jet fuel into a skyscraper will cause the fuel tanks to rupture, and wiring to be exposed, causing sparks to ignite the fuel, causing a massive fire, causing the materials of the building to weaken, causing the building to collapse.

2. The fallacy is often used to set up a false dilemma fallacy, wherein the choices presented are the extreme end of the slippery slope and not going down the slope at all. This is a technique to make the false dilemma appear necessary, while distracting one's opponent from the falciousness of the dilemma, as well as the lack of causality in the slippery slope itself.

Example 1:

Accident victim: "I think we should install some cameras at that intersection where I was hit. It's a bad intersection; people might be less inclined to run the red light if they thought they'd get a ticket."

Libertarian: "Have you considered the impliations of that? Once we install traffic cameras at dangerous intersections, that will cause the government to put them at all intersections! Then they'll be in all public places, then in all privately owned public places like restraunts, and in a few years you'll have them in your home! You want to throw away our precious liberties so Big Momma Government can make you feel safe!"

This should be ridiculous for obvious reasons. Cameras do not breed, nor cause other cameras to exist. The legal justifications one could cite for dangerous intersections do not apply once we get away from the narrow purpose of preventing frequent traffic accidents.

Example 2:

Yoda: "Fear leads to anger, anger leads to hatred, hatred leads to suffering"

While this seems like a logical course of events, and was exactly the path Anakin followed, none of those emotions necessarily cause the next. Fear can be overcome without anger resulting. Anger does not lead to hatred if the anger passes or is resolved. Hatred may disappear if the incentive to hate is gone, or if a reason to put it aside exists.

Example 3:

Corrections Officer: "I'm writing you up for being out of place, Jones."
Inmate Jones: "Yeah, right man, you right me up today, an' tomorrow you be writin' up the whole bloc for standin' in the wrong spot. Pretty soon you have some pissed off motherfuckers in here an' you have a riot on y'all hands."

In this last example, writing up an inmate for bad behavior one day will not necessarily cause the CO to write up inmates for petty reasons in the future. Writing inmates up for petty reasons would indeed probably result in pissed off inmates, but pissed off inmates do not always riot. Inmates become angry over all manner of trivial matters, and few of these lead to riot.

This last example, however, is a very hard type of slippery slope to spot, because one of the steps does (or is pretty likely) to cause the next (i.e. petty write ups will anger the inmates). It is still a falacious argument as a whole, however, because the entire sequence must be linked causes and effects, not just a portion.
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Cum hoc ergo propter hoc

Postby haard » 2006-04-06 08:56am

Cum hoc ergo propter hoc
(with this, therefore because of this)


The fallacy is that you assume that casuality is proved through correlation. Sometimes hard to spot, often seen in work life (correlating curves anyone?) and politics. Can easily be found by opening the first tabloid you see (and most likely, any newspaper). Stems from ignorance of casuality, and is often used to make statistics 'prove' whatever you want.



Example 1
[Jim-Bob] All users at the sci-fi board are dorks with glasses, so sci-fi is bad for your eyes!

Even if the premise was true, the correlation does not show the cause.


Example 2
[Rev. Smith] The recent rise of rap and hip-hop that glorifies crime and violence has been shown to correlate with higher crime rates amongst the youth - obviously, this music subverts our youth and incites crime!

This may or may not be true, but to show that the music is a cause you have to show the mechanism, not the correlation. Crime rates can be shown to correlate to a great many things - for example US crime rate have been shown to correlat with the strength of the economy, and ice-cream sales.
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Thus Aristotle laid it down that a heavy object falls faster then a light one does.
The important thing about this idea is not that he was wrong, but that it never occurred to Aristotle to check it.

- Albert Szent-Györgyi de Nagyrápolt

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Durandal
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Postby Durandal » 2006-04-08 06:00pm

Amazing how "no discussion" seems to be lost on some people.
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haard
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Postby haard » 2006-04-10 02:15am

Post hoc ergo propter hoc
(after this, therefore because of this)

Post hoc is the assumption that since A comes before B, a causes B.

Example 1:
[Boss] Right after we hired you, our sales went down. Clearly, the customers don't like you, so you are fired!

Example 2:
[Mary-Sue]You know, the day before I got the cancer diagnosis, I was cursed by a Wiccan! Clearly, that witch gave me cancer!

Even though an event A is show to come before some other event B, there is no proof that it is the cause - not even if A can consistently be shown to always come before B. As in the case of post hoc, you need to show the mechanism, not the correlation.

Both post hoc and cum hoc are examples of non casua pro casua, or false cause fallacies.
If at first you don't succeed, maybe failure is your style

Economic Left/Right: 0.25
Social Libertarian/Authoritarian: -5.03

Thus Aristotle laid it down that a heavy object falls faster then a light one does.
The important thing about this idea is not that he was wrong, but that it never occurred to Aristotle to check it.

- Albert Szent-Györgyi de Nagyrápolt

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Postby Xeriar » 2006-04-30 06:48am

Loaded Question a.k.a. False Premise

A question in which a point is assumed to be true without proof, though the questioner need not be aware of this to make it a fallacy.

Sometimes incorrectly called Begging the Question or Complex Question, these are related but different question.

Example 1:
"Have you stopped beating your wife?"

Perhaps the most famous example, though you can substitute 'beating' for nearly any verb and 'wife' for nearly any noun. This particular sentence assumes the subject is beating his assumed wife, neither of which are necessarily true with only the context of the question provided.

Example 2:
"Dungeons and Dragons? Why do you play that satanic game?"

This is a more obvious example, since here we can at least assume that the person being questioned plays. The questioner assumes that D&D is satanic, and it is still a fallacy whether they honestly believe it or not.

Example 3:
"How can you deny all the evidence for the christian god?"

Another straightforward one - there is no such evidence available for public scrutiny.

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Postby Xuenay » 2006-08-01 06:06pm

Generalization from Fictional Evidence

Coined (AFAIK - googling didn't bring up other hits) by Eliezer Yudkowsky in his speech Predicting the Future. In this fallacy, a person claims events as they unfolded in a fictional work to be evidence for his cause, usually to demonstrate the consequence of a certain technology or policy. This is a fallacy because the work is fiction, and the author did not really know how things would actually turn out. This is often a form of the Slippery Slope fallacy at the same time.

Example 1: In Star Trek, holodecks routinely go out of order and nearly kill the people within. Therefore, we should ban all holograms.

Example 2: Human genetic engineering will lead to a biological caste system where everybody is given predetermined roles at birth - just look at Brave New World.

Example 3: We can't allow video camera surveillance of public places or we'll soon end up in a state where the government has strict control of us all, just like in 1984.
"You have zero privacy anyway. Get over it." -- Scott McNealy, CEO Sun Microsystems

"Did you know that ninety-nine per cent of the people who contract cancer wear shoes?" -- Al Bester in J. Gregory Keyes' book Final Reckoning

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Postby Rogue 9 » 2008-02-06 09:58am

Undistributed Middle

A syllogistic fallacy in which the middle term is not distributed at least once, leading to equivocation without evidence. See here.

Example 1

"I am happy with saying things like this: Star Destroyers shoot lasers at asteroids and they blow up. The Enterprise shoots photon torpedoes at asteroids and they blow up. Photon torpedoes are about as destructive as SD lasers."

(Actual argument from a debate I'm currently engaged in. Obviously, that photon torpedoes and turbolasers both destroy asteroids does not mean that they are necessarily equal in power; this would only be true if the supportive premises included evidence that asteroid destruction was the upper limit of both weapons.

As a syllogism, the argument breaks down like so:

Photon torpedoes destroy asteroids.
Turbolasers destroy asteroids
Therefore photon torpedoes are the same as turbolasers.)

Example 2

The classic:

All A's are C's.
All B's are C's.
Therefore all A's are B's.

Taken in its abstract form, it seems to make sense; since A=C and B=C, A=B. Mathematically this is so, which is why it seems logical; but replace the placeholders A, B, and C with appropriate actual subjects and properties and you see where it breaks down:

All dogs are four-legged.
All cats are four-legged.
Therefore all cats are dogs.

The problem, I think, is obvious.
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General Soontir Fel
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Postby General Soontir Fel » 2008-02-06 02:19pm

No True Scotsman

Trying to change the definition of a term so that something the debater does not wish to fit the term doesn't, although it does fit the term by the term's actual definition.

Example 1 (obvious)
Yes, the Crusaders launched a religious war of aggression, and slaughtered innocents. That's un-Christian. Therefore, the Crusaders weren't true Christians.

Example 2:
A: How can you say conservatives believe in limited government? Look by how much Bush had increased government spending.
B: Well, that just proves Bush isn't really a conservative.[/i]

Example 3 (subtle):
A: Of course we have seen evolution. We've seen speciation in fruit flies, bacteria becoming resistant to antibiotics, etc.
B: That's not really evolution. Bacteria are still bacteria, they haven't evolved into higher life-forms.
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Postby Darth Servo » 2008-02-06 03:31pm

Rogue 9 wrote:Reductio ad Hitlerum

Bearing a name derived from the reductio ad absurdum logical argument and closely related to Godwin's Law, this fallacy is that of arguing that any concept, idea, or action supported by Hitler or the Nazi Party is therefore evil or morally wrong.

Example 1
Ted: Vegetarianism is a better, healthier, and moral way of life.
Fred: But Hitler was a vegetarian! Vegetarianism = Nazism!

(Obviously, vegetarianism is not immoral simply because Adolf Hitler was a vegetarian. I'll try for a more subtle example, but since the fallacy is by nature so blatantly obvious, it won't be very much so.)

Example 2
Bob: Corporations are out of control. The government should put the industrialists on a leash before this gets any worse.
Tom: The Nazi Party incorporated and controlled German industrialists, Bob. Are you sure you want to set up that situation again?

(The above not only utilizes reducto ad Hitlerum, but also appeals to consequences in an oblique fashion, thus becoming doubly fallacious yet far more effective against an inattentive opponent.)

This is more generally referred to as "Guilty by association" and it need not be just the nazis. It can be Stalin/Communists or Saddam Hussein or any other evil person or group.

There is also the converse: Innocent by association

Definition
A given action or belief is declared to be good, or at least non-harmful because a well respected person or group participated in or accepted it. Because said person/group accepted it, its known harmful or false properties can be ignored.

Example 1
Lots of famous scientists and even doctors smoked, therefore smoking can't be stupid or harmful.

Example 2
The founding fathers accepted slavery, so there is clearly nothing wrong with slavery.

Example 3
Sir Isaac Newton was a Christian so Creationism must be legitimate.
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