Follow TV Tropes

Following

Context UsefulNotes / LogicalFallacies

Go To

1->''"A foolish consistency is the hobgoblin of little minds, adored by little statesmen and philosophers and divines."''
2-->-- '''Creator/RalphWaldoEmerson'''
3
4Logic. Every story needs some of it, unless you just want a [[MindScrew series of unconnected images]] and [[GagSeries no plot to speak of]].
5
6The problem is that logic requires writers to think pretty hard about what they write, and not all writers have time or inclination to do so. So they take shortcuts, creating fallacies which at best can lead to {{plot hole}}s or, at worst, undermine the entire story.
7
8Fallacies are common errors in logic. By strict standards, fallacies don't address the truth of the premises or syllogism; they only address the ''validity of the logic'', and as the [=Sound/Valid/True=] rule demonstrates, "truth" and "validity" are not the same thing when speaking of formal logic. There is a reason there are Critical Thinking classes.
9
10Where deductive logic is valid, the conclusion must be true if the premises are true. "If it rains, then the sidewalk will be wet" is valid, so if you know that it rained, you know that the sidewalk will be wet. If you simply reverse the terms and say "if the sidewalk is wet, then it rained", this would not be valid; likewise, negating the terms, yielding "if it did not rain, then the sidewalk is not wet", is also invalid. To correct this, you need to construct a "contra-positive," where you [[BreadEggsBreadedEggs reverse the terms as well as negating them]] to get "if the sidewalk is not wet, then it did not rain".
11
12However, inductive logic[[note]]Not to be confused with mathematical induction, which is a strictly logical, deductive method.[[/note]] involves reasonable inferences of what might be true, but not necessarily. A sidewalk could be wet due to a passing street sweeping vehicle or neighbours carelessly watering their lawns. Seeing a wet sidewalk and concluding that there was rain is fallacious — not deductively valid — but it is not necessarily false, nor is it necessarily an unreasonable inference to make.
13
14Logical fallacies are faulty deductive reasoning. This doesn't mean that they aren't effective at persuading. Many of them are extremely effective tools of persuasion. The key is that there are two primary routes of persuasion: the central (logical) route and the peripheral (emotional) route. To persuade someone using the central route, you ''need'' logic; a logical fallacy will make your argument fall flat on its face. To persuade someone using the peripheral route, you don't need logic; you simply need to play on their emotions. Some people are impassive to emotional appeals, and so you must use logic to persuade them; others are confused by logic, and so must be persuaded through emotion.
15
16However, one must keep in mind that — depending on the surrounding circumstances — a deductively fallacious argument may still, nonetheless, [[RightForTheWrongReasons be a reasonable and (inductively) logical argument that has decent prospects of being true despite the deductive logic being invalid]]. A classic example is if someone were to examine a million swans and note that all of them were white. It would be a (deductively) logical fallacy to conclude that "all swans are white". You could not make that conclusion unless you know that you had examined all swans in the universe. That doesn't make it illogical, however. If no one had ever seen a black swan, it might be rather sensible. Plus, this whole type of analysis is complicated when you talk about statistical trends. For these kinds of special cases, see the Fallacy Fallacy below.
17
18For examples of characters falling into these fallacies (intentionally on the writer's part), see the main LogicalFallacies index. This is not an exhaustive list, and there are more fallacies in that index.
19----
20!!Specific fallacies:
21[[foldercontrol]]
22[[folder:Ad Hoc]]
23Ad hoc is a fallacious debating tactic (also called a "just so story" or an "ad hoc rescue") in which an explanation of why a particular thing ''may be'' is substituted for an argument as to why it ''is''; since it is therefore not an argument, it is not technically a fallacy, but is usually listed as one because it is a substitution for a valid argument. It is similar in form to MovingTheGoalposts, but protects the argument by adding additional speculative terms rather than changing the meaning of existing ones.
24
25Users of ad hoc claims generally believe the excuses and rationalisations serve to shore up the original hypothesis, but in fact each additional speculative term weakens it. This is both due to the speculations being based simply on the faith that there ''might'' be an explanation, and because each additional term makes the hypothesis weaker according to the principle of OccamsRazor.
26
27"Possibly," "probably," "maybe," "might" and "could" are all good markers of ''ad hoc'' claims.
28
29It's a very common sight in Administrivia/{{justifying edit}}s aimed at any supposedly negative trope, particularly if that edit calls upon things that ''might'' have happened to cause the item described. For example:
30
31->''"There is a glaring PlotHole in this movie, since it is said that magic cannot work in the Dark Zone, yet later on Alice resurrects Bob while fighting the Phantom Lord."''
32->''"It's possible that Alice learned a form of magic that does work in the Dark Zone, and that's what she used to save Bob."''
33
34Here the second poster is not presenting evidence: rather, they are explaining what the evidence they ''do not have'' ought to look like.
35[[/folder]]
36
37[[folder:Affirming the Consequent]]
38This claim is most simply put as:
39
40->If A, then B.\
41B.\
42Therefore, A.
43
44It's a fallacy because at no point is it shown that A is the ''only'' possible cause of B; therefore, even if B is true, A can still be false. For example:
45
46->If my car was Ferrari, it would be able to travel at over a hundred miles per hour.\
47I clocked my car at 121 miles per hour.\
48Therefore, my car is a Ferrari.\
49
50This is popular in conspiracy theories. Here the fallacy is fairly obvious; given the evidence, the car ''might'' be a Ferrari, but it might also be a Bugatti, Lamborghini, or any other model of performance car, since the ability to travel that fast is not unique to Ferraris. Hell, it might even be a Subaru Outback. Note that while this may appear to call all hypothesis / evidence experiments fallacious, they are based on additional evaluations of the likelihood of ''other'' theories, thus establishing that A ''is'' a likely cause of B.
51[[/folder]]
52
53[[folder:Anecdotal Fallacy]]
54Anecdotal evidence is basically saying "''X'' happened to me[=/=][[IHaveThisFriend someone I know]][=/=]someone I heard about" in a discussion and/or argument. If it's true that ''X'' happened to this person (which is not proven by the assertion alone), it proves only that ''X'' is not impossible. It most certainly does not establish that ''X'' has ever happened more than once, or that ''X'' is common or pervasive - and that's what this fallacy about. The anecdotal fallacy is using anecdotes instead of actual statistics and making general rules and grand claims off them, an accurate picture of the reality of the matter be damned. Crops up often in heated arguments and amidst Hasty Generalisations, whereby an anecdote is not just used to illustrate or critique a general rule but as 'proof'[[note]] protip: it isn't [[/note]] in itself. As they say, "The plural of 'anecdote' is not 'data'".
55
56->"According to statistics, smoking causes you to die young. But my Grandmother Sally smoked like a chimney and lived until she was 95, so clearly, the statistics are wrong."
57
58As a rebuttal, [[DeadpanSnarker one might]] [[HypocriticalHumour simply point out]] that they met a man on the way home who said that anecdotal evidence doesn't prove anything.
59
60Anecdotal Evidence is extremely prone to ConfirmationBias; when it doesn't fit one's viewpoint, it can be very easily dismissed as this fallacy. If it does fit one's viewpoint, it's a perfect example of that viewpoint applying to real people in the real world.
61[[/folder]]
62
63[[folder:Appeal to Consequences]]
64The Appeal to Consequences happens when the truth or falsity of a statement is decided by the positive or negative consequences of it.
65
66->If climate change is occurring ''and'' is caused by humans, then we are obligated to do something to stop or slow it.\
67The most effective way to do so is for businesses to cut down on carbon emissions.\
68The short term costs of cutting carbon emissions would be economically devastating.\
69Therefore, climate change is either not occurring, not caused by humans, or both.
70
71Or, conversely:
72
73->If climate change is occurring ''and'' is caused by humans, then we are obligated to do something to stop or slow it.\
74The most effective way to do so is for businesses to cut down on carbon emissions.\
75The long-term economic benefits of stopping global warming will be enormous.\
76Therefore, climate change is both occurring ''and'' caused by humans.
77
78Ain't it fun when you can use the same fallacy and essentially the same argument and "prove" diametrically opposite conclusions?
79
80For contrast, the following is ''not'' Appeal To Consequences:
81
82->Human industry is producing massive amounts of CO[[subscript:2]].\
83CO[[subscript:2]] causes climate change regardless of source.\
84Even minor alterations to the Earth's climate would be catastrophic for humanity.\
85Q.E.D.: If humans wish to destroy themselves, humans should maintain or increase their current carbon emissions.
86
87Instead, this is a contingent statement based on absolute facts that forms a chain of cause and effect.
88[[/folder]]
89
90[[folder:Appeal to Fear]]
91Also called:
92* ''Argumentum ad metum''
93* ''Argumentum in terrorem''
94* ScareEmStraight
95* CantGetAwayWithNuthin
96
97The slightly more subtle form of AppealToForce, Appeal to Fear isn't a direct threat, but nevertheless is based on the idea that something terrible will happen unless you agree with a given position. The difference can be summarized like this:
98
99->'''Appeal to Force:''' "Agree that 2 + 2 = 5, or else I'll beat you up."
100
101->'''Appeal to Fear:''' "Agree that 2 + 2 = 5, or else social order will collapse, criminals will go free, and they will beat everyone including you up."
102
103This is a fallacy because whether an outcome is frightening has no relevance to whether the initial statement is true or not. Social order may collapse if you disagree that 2 + 2 = 5 (as in ''Literature/NineteenEightyFour''), but that does not mean that 2 + 2 = 5. A type of Appeal to Consequences, where someone is supposed to be afraid of an outcome and therefore assume it to be true or false as a result. In marketing, this fallacy is known as FUD ("Fear, Uncertainty, and Doubt") and is applied to the use of vague criticisms of opposing products in order to try to persuade consumers to buy by brand.
104[[/folder]]
105
106[[folder:Appeal to Ignorance]]
107!!! Also called
108* Argument from Ignorance
109* Argument from Lack of Imagination
110* Argument from Personal Incredulity
111
112The claim that a statement is true simply because it has not been proven false, or that a statement is false simply because it has not been proven to be true. More exactly, that if a claim A is incorrect, a separate claim B is automatically correct: it is thus a type of false dilemma, and based on Shifting the Burden of Proof onto whichever side of the argument you want to lose.
113
114->"It's clear from the knife in this man's back that he was murdered."
115->"You don't know for sure that's how the knife got in his back, therefore he was not murdered."
116
117Or:
118
119->"Since you haven't found a murder weapon yet, it's obvious this man was poisoned."
120
121The essence of the fallacy is that if the original argument cannot explain everything ''right now'', it must be false: the person committing the fallacy discards the possibility of gathering more evidence. This makes it essentially a claim of personal omniscience; if the arguer cannot imagine a way for something to have happened, it is clearly impossible: it is thus closely related to the PerfectSolutionFallacy, where solution A is discarded due to failing to measure up to an idealized perfect solution B. In addition, it eliminates all ''other'' possible explanations in favor of a preferred one: in the second example, for instance, the idea the victim was, say, strangled is simply discarded in favor of the preferred conclusion, without any clear reason.
122
123Famously refuted by Creator/CarlSagan with the statement, "Absence of evidence is not evidence of absence."
124[[/folder]]
125
126[[folder:Appeal to Pity]]
127Also called ''Argumentum ad Misericordiam'', the Appeal to Pity is attempting to make someone feel sorry for either the arguer or the subject of the argument in order to convince them to accept the argument, regardless of its validity.
128
129-> "Sir, you shouldn't fire me, even though I'm chronically late, bicker with all the other staff, and consistently fail to finish my tasks on time, because I have a sick wife and four children, and if I lose my job we'll be thrown out of our house and have to live on the street."
130[[/folder]]
131
132[[folder:Appeal to Ridicule]]
133Also known as the Appeal to Mockery, the Horse Laugh, or ''reductio ad ridiculum'', the Appeal to Ridicule is a simplistic fallacy in which it is suggested an argument is false by presenting it in a way in which it appears silly and/or trivial. This is often also a strawman or an Appeal to Ignorance.
134
135->"According to quantum theory, an electron can be in two places at once! Have you ever heard anything so stupid? It must be wrong!"
136
137This fallacy differs from ''reductio ad absurdum'', a legitimate debating technique; there, it is demonstrated that an absurd conclusion naturally follows from the underlying logic of an opponent's argument, therefore showing the argument as invalid. However, an attempt at ''reductio ad absurdum'' that itself uses faulty reasoning can leave you with this.
138
139Also, just because an argument uses ridicule does not mean it runs afoul of this. A person who delivers a withering, logically sound counterattack in a mocking, rude manner is being a jerk. If the argument is still sound, it stands regardless of how insulting the phrasing is. It only becomes a fallacy when the arguer fails to explain ''why'' what they are arguing against is stupid or ridiculous and [[TakeOurWordForIt just expects you to go with it]].
140
141A variation is ''argumentum ad lapidem'' ("appeal to the stone"), in which a statement is dismissed as absurd, but with no proof that it's absurd.
142[[/folder]]
143
144[[folder:Appeal to Wealth]]
145Claiming that a position is correct because the rich or famous support it. This is the basis behind {{Celebrity Endorsement}}s, especially when the celebrity's claim to fame is not relevant to the issue. See ScrewTheRulesIHaveMoney and ColbertBump.
146[[/folder]]
147
148[[folder:Argumentum ad Nauseam]]
149Also known as proof by assertion or the Big Lie Effect, ''argumentum ad nauseam'' is repeating a statement until nobody cares to respond anymore, then claiming you're right since nobody contradicts you. A favourite variation is to insist you've refuted your opponent's argument previously without ever actually doing so, and then go on to state that you can't help that they didn't understand it. While it sounds simplistic, this fallacy can be maddeningly effective. In forums with content rules, the debater is often trying to frustrate their opponent into flaming them, hoping to win by default.
150
151See also ArgumentOfContradictions, in which ''both'' sides repeat their side of the argument briefly, rapidly, and back-and-forth, or simply shout something in the form of "Is not!" "Is too!" in the hope of wearing down an opponent or simply not being willing to back down or provide actual logical reasons.
152[[/folder]]
153
154[[folder:Bandwagon Fallacy]]
155The Bandwagon Fallacy is the suggestion that because something is becoming popular, it should be accepted quickly or the person being spoken to will lose out in the long run. The name comes from the classic idea of getting on the bandwagon before it leaves; in this fallacy, the fact that there are a lot of people on the bandwagon and it might leave are the ''only'' reasons given to accept, with no reason why getting on the bandwagon is actually a good idea (or, for that matter, why there ''is'' a bandwagon).
156
157This is referred to as ''Fear of Loss'' in sales; a salesman will claim that he's only allowed to sign up a certain number of people to a fantastic deal and has already got most of his quota for today, so if the person he's speaking to doesn't act they stand to lose out.
158
159There are also times this argument is valid, such as when there are what economists call [[http://en.wikipedia.org/wiki/Network_effect network effects]]. In brief, if the value of a good or service changes based on the number of users, then pointing out the number of using it could be valid. For example, when telephones were adopted, their value increased with every new telephone added to the network. If business software is used by many companies, being ubiquitous is a selling point. If no one else uses an instant messenger, it's useless, but if everyone uses it, it's more valuable to the end user. If all of one's friends use a specific social networking site and you want to use social media, it makes sense to follow your friends. If a cell phone company allows unlimited calls between two members of their networks, the number of clients they have and their demographics are both legitimate concerns. If most counties and companies are using a particular shipping container, rail-road gauge, or standard of measure, there's good reasons to adopt the same standards.
160[[/folder]]
161
162[[folder:Begging the Question]]
163!!! Also called:
164* Petitio principii (Latin: "pursuit/attack of the source")
165
166Also called "Circular Reasoning," begging the question is "proving" that something is true by taking your conclusion as one of your premises, usually done implicitly rather than explicitly. Few people are fooled by [[CircularReasoning having your conclusion as your only premise]], as in "Joe is mad at Jill, therefore Joe is mad at Jill." In rhetoric, such arguments are called ''[[http://en.wikipedia.org/wiki/Tautology_%28rhetoric%29 tautologies]]'', and they're essentially [[MeaninglessMeaningfulWords a pretty but meaningless]] way of saying [[DepartmentOfRedundancyDepartment the same thing twice]]. Therefore an argument which is begging the question often isn't obvious, even to the one making it. A premise may be substantially identical to or assume the truth of its conclusion, but be concealed by using different vocabulary, phrasing, sentence structure, or go unstated entirely.
167
168Logic, meanwhile, has its own form of [[https://en.wikipedia.org/wiki/Tautology_%28logic%29 tautology]]: a statement or chain of statements which are sound, valid, and true under any condition.[[note]]"[[Administrivia/NotASubversion A trope is either subverted or not subverted.]]"[[/note]] Begging the question is what happens when you confuse the two.
169
170Put broadly, this fallacy applies to any argument where one or more premises are at least as contentious as the conclusion itself, and for the same reasons, such as:
171
172-> Alice says she is honest.\
173If an honest person says something, it must be true.\
174Therefore Alice is an honest person, because an honest person says so.
175
176An example where the fallacy is more hidden might go something like this:
177
178-> The relationship between capitalists and laborers can only be exploitative, and mutually beneficial coexistence between them is impossible. Therefore, the path of historical development inevitably leads to socialist revolution.
179
180In this example, both the premise and conclusion are based on Marxist ideology. If one were to accept one, by definition one already accepts the other. In other words it is not an "argument" at all, but merely a statement that says, "I am a Marxist."
181
182Note that begging the question in arguments can be perfectly valid, logically speaking. However, they are not considered convincing because they do not prove anything other than what was already assumed.
183
184"Begging the question" is often used colloquially to mean "raising the question". (Example: "With the rise of online media, this begs the question: do public libraries have a future?") This usage is a common BerserkButton for academics aware of the original meaning. It doesn't help that the original phrase was first translated from Greek into Latin, and from Latin into English, resulting in the confusing phrase, "Begging the question," which is incomprehensible to English speakers (there being no begging nor question involved) unless one is already aware of its meaning.
185[[/folder]]
186
187[[folder:Bulverism]]
188Bulverism happens when one party simply assumes that the other party is wrong and explains their reasons for wanting to believe it rather than addressing the argument itself. It combines Begging the Question with the Genetic Fallacy.
189
190Wiki/TheOtherWiki expresses Bulverism as:
191
192* You claim that A is true.
193* Because of B, you personally desire that A should be true.
194* [[TooGoodToBeTrue Therefore, A is false.]]
195
196In short, it can be summarized as "You're only claiming X to be the case because you ''want'' X to be the case!". This is fallacious since whether or not someone wants something to be true because it would benefit them personally has no bearing on whether or not it actually ''is''.
197
198The term was coined by Creator/CSLewis in an essay of the same name in which he describes the (fictional) origin of the fallacy: a boy named Ezekiel Bulver heard his parents arguing when his mother said "Oh, you say that because you are a man." at which point Bulver realized that "refutation is no necessary part of argument".
199
200Lewis himself summed up the fallacy as "to assume without discussion that [your opponent] is wrong and then distract his attention from this (the only real issue) by busily explaining how he became so silly."
201[[/folder]]
202
203[[folder:Cab Driver's Fallacy]]
204Similar to the SunkCostFallacy, this is having a particular goal in mind and refusing to give up on it, however impossible it seems, while also ignoring the possibility of doing even better. Named for the tendency of taxi drivers to try to earn a specific amount each day. On slow days they will keep going to reach the target, while on good days they will quit early as soon as the target is reached. They would do much better if they would go home early on slow days (thus saving gas, as well as wear and tear on the car, not to mention the driver) and keep going past their target if it's busy (when they barely have to drop off one fare before getting another one).
205
206So far as cab drivers are concerned, this may be explained by risk-aversion. When it comes to something like income, most people are risk-averse - they would rather be guaranteed a steady flow of money rather than risk a large variance in the amount received (possibly negative) turn-by-turn, even if the latter would yield more money in the long run.
207[[/folder]]
208
209[[folder:Denying the Antecedent]]
210The flip side of Affirming the Consequent, this is where you say that because the initial conditions did not happen, the result is impossible.
211
212-> If a person is wearing a hat, they have a head.\
213I am not wearing a hat.\
214Therefore I do not have a head.
215
216Note that, by the [[http://en.wikipedia.org/wiki/Contrapositive contrapositive]] rule, these two fallacies are equivalent. For example, you could replace "If a person is wearing a hat, they have a head" by the logically identical statement "If a person has no head, they aren't wearing a hat" to turn the first example of denying the antecedent into an example of affirming the consequent.
217[[/folder]]
218
219[[folder:Fallacy Fallacy]]
220Also known as the Appeal to Fallacy, the [[StrawVulcan Mister Spock Fallacy]], the idea that "Fallacy means Wrong", the Zeroth Law of Fallacies, and the Bad Reasoning Fallacy, this concerns a claim that a position must be false because the argument used to get to that position is invalid or used a fallacy. It may sound like a rational thing to do since by definition a fallacious argument does not make sense, and this rule may seem like a {{mindscrew}}y special case, but...
221
222->Tom: All cats are animals. Ginger is an animal. This means Ginger is a cat.
223->Bill: You just committed the "affirming the consequent" logical fallacy. Sorry, you are wrong, which means that Ginger is not a cat.
224
225Bill's rebuttal is an appeal to fallacy, because Ginger may very well be a cat; we just can't ''assume'' so from Tom's argument.
226
227In other words, pointing out somebody's fallacy is not fallacious in itself (you're doing it right), but using this as "proof" that their claim is false is the Fallacy Fallacy. Somebody arguing their point badly doesn't automatically mean they are wrong. The best you can say is that they have not convincingly supported it. This also applies to the Fallacy Fallacy itself: Bill's argument is a fallacy, but it would be the same fallacy to conclude that Ginger ''is'' a cat because of that, since Tom's only "proof" is not a valid argument.
228
229It should be noted that the burden of proof applies here: if the only ''reason'' to accept a claim is a fallacious argument, accepting the claim anyway is ''unreasonable''. If our null hypothesis is that Ginger is not a cat, Tom has given us no reason to change this assumption. As above, it may well be that Ginger actually ''is'' a cat, but logic doesn't decide what's true, it decides what makes sense.
230
231Another excellent example of how a [[RightForTheWrongReasons false argument is combined with a true conclusion]]: in medicine, pressure around the brain can cause severe headaches. Ancient surgeons assumed that it must be demons in the patient's head causing the pain, and that exposing them to light would kill them or drive them out; therefore, they drilled holes in the patient's skull. The end result relieved the pressure and actually ''did'' cure the headaches, even though their reasoning was entirely faulty.
232
233An argument using fallacious reasoning is consequentially capable of being true. In logic, "invalid" (fallacious argument) and "false" are ''not synonymous'' (See [=Sound/Valid/True=] for a more complete explanation of this. There are reasons why extensive Critical Thinking courses exist.) This is related to how [[Administrivia/TropesAreTools logical argument is used as a tool rather than as a fact-in-itself, and that logical validity can sometimes be surpassed by an objective scientific fact]].
234
235It should be noted that there are some exceptions: namely, fallacies of distraction or relevance. A {{Strawman}} argument may still have a true conclusion, for example, but by definition it is an irrelevant conclusion since it does not address the opponent's real argument. Demonstrating the opposing argument is a strawman is therefore a valid rebuttal.
236[[/folder]]
237
238[[folder:Fallacy of Composition]]
239Claiming that because a statement is true of the parts, it must be true of the whole. For example:
240
241->Everything is made of atoms.
242->Atoms are invisible to the naked eye.
243->Therefore everything is invisible to the naked eye.
244
245A type of generalisation fallacy.
246[[/folder]]
247
248[[folder:Fallacy of Division]]
249The opposite of the Fallacy of Composition, this happens when someone generalizes from a whole to the parts. For example:
250
251->A colony of ants can destroy a tree.\
252Therefore, this ant can destroy that tree.
253[[/folder]]
254
255[[folder:Frozen Abstraction]]
256When an argument implicitly assumes that a specific member (or subset of specific members) of a wider class ''is'' the wider class. Similar to the Fallacy of Composition in transferring one thing's properties to everything else in its class, and overlaps at times with FalseDichotomy (which occurs when two members of a wider class are claimed to be the only members of the wider class and that a choice must be made between them). This fallacy is often caused by an unstated premise.
257
258-> "An Egoist theory of ethics is a contradiction in terms".
259
260This assumes that "ethics" is a synonym for "non-self-interested."
261
262-> "Anarchism is not a political ideology because politics is about the role of the State; advocacy of a stateless society is not a political position."
263
264This assumes that the role of the State must be an active one -- i.e., the State must exist. (This applies whether one is arguing that Anarchism is not a valid political position, or that Anarchism is somehow "above" politics.)
265[[/folder]]
266
267[[folder:Genetic Fallacy]]
268Rejecting (or accepting) something solely on the basis of its origin, without looking at meaning or context. This ignores the fact that even a less credible source is sometimes, or can be, right. Alternately, that a more credible source is sometimes, or can be, wrong.
269
270This is seen in any case where a source is either highly disparaged or esteemed. Sources will commonly be accepted or dismissed out of hand without looking into the actual validity of their facts or arguments.
271[[/folder]]
272
273[[folder:Human Nature Fallacy]]
274There are many people in the world who would be considered as bad [[Administrivia/RuleOfCautiousEditingJudgement (at least in the views of some people)]] and would be seen as the "worst humanity has to offer". However, there are also just as many people who actively try to help whoever they can and to try to make the world a better place, [[KnightInSourArmor even if they see the worst aspects of such.]]
275
276However, [[StrawNihilist people who assume]] that such actions were [[HumansAreBastards the result of human nature that is present in all human beings]], tend to forget about those other kinds of people who actively try to help people in need (or at least support those, but cannot do much about it). These characters would assume that such actions are reflective of the entire human race, making flimsy claims of many people who do help only do so out of {{Pride}} and publicity ([[TruthInTelevision while there are some who do that]], there are also much more people who genuinely want to help) and that ideas of hatred, prejudice and self-destruction are inherent in ''all human beings.'' They all reject claims of RousseauWasRight and the idea of a Blank Slate, replacing them with HumansAreBastards (or [[HumansAreTheRealMonsters the real monsters in certain cases]]). Sometimes, they would deny that they share those aspects with humanity, [[PsychologicalProjection claiming that their suffering was of the actions of humanity]] [[{{Hypocrite}} (when it could be their own fault)]] or embrace that they're part of humanity and using that as an excuse for their actions.
277
278More blatant examples include dismissing the victims of such atrocities as being just as bad as the perpetrators, including children as part of their perceived Human Nature and igniting a [[DomesticAbuse Family Feud]] between family members, just because they perceive them as [[HumansAreBastards bastards]] deep down, no matter how they treated them.
279
280[[WideEyedIdealist The other way around]] is the assumption of all of humanity being good deep down, no matter how cruel their actions may be. Some may say that such actions were only [[RousseauWasRight brought upon due to their upbringing.]] Whilst a person can be influenced by their upbringing, characters who believe humanity is inherently good from birth would not accept that there are people who are deep down cruel. They would try to reason with even the most negative aspects of humanity, preferring to appeal to whatever little or no aspect of goodwill they have over actively combating them. They would also not recognize that there are people who are [[MoralEventHorizon completely beyond redemption.]]
281
282The more lighthearted variant is when someone assumes that all humans share a similar opinion on something, or similar habits and the like, when it's most likely not true. Such as "everyone likes spicy foods" or "everyone likes a certain film" or "[[FreudWasRight everyone thinks about sex]]".
283
284This idea is rarely treated as a necessary worldwide view in fiction, but when it does happen, there is a high chance of TooBleakStoppedCaring or TastesLikeDiabetes and accusations of the Author expressing this view.
285
286See also TragicBigot and AppealToInherentNature. Compare BlankSlate, HumansAreFlawed. Contrast HumansAreBastards, InYourNatureToDestroyYourselves, HobbesWasRight (for the cynical version) and HumansAreGood, RousseauWasRight (for the idealistic version). Also contrast HumansAreIndexed, which list common human archetypes.
287[[/folder]]
288
289[[folder:Hypostatization]]
290Sometimes related to the FourTermsFallacy, this is treating an abstract idea as a physical object. For example, "Eating ice cream feels good. Therefore, we should give ice cream to criminals, so they become good." This assumes that "good" is a thing that can be measured and which is a physical property of ice cream — in fact "good" is an unmeasurable and quite subjective concept. Similarly, you can't go down to the store and pick up a can of consideration or a box of blue; they are ''attributes'' of things, but do not exist independently of them.
291
292A variation is treating a thought experiment as a physically workable one; for example, imagining that one could use [[UsefulNotes/SchrodingersCat Schrödinger's box apparatus]] to actually cause quantum superposition of a cat.
293[[/folder]]
294
295[[folder:Irrelevant Thesis]]
296Also called ''ignoratio elenchi'' ("ignoring refutation") or an irrelevant conclusion, this happens when you have not refuted the opposing position at all, but are acting as though you did. It's really a superfallacy, in the same way that "RuleOfCool" is a supertrope; there are a number of fallacies which are all types of "Ignoratio Elenchi", among them all Appeals To Consequences, all Appeals To Emotion, all Strawmen and Red Herrings, Ad Baculum, Ad Nauseum, and all Ad Hominems.
297[[/folder]]
298
299[[folder:Loaded Words]]
300Loaded words or loaded language describes the misleading use of emotionally loaded language in order to win an argument.
301
302Besides a word's definition, most words have a connotation that implies that its subject is either good or bad. For example, both the words "cabin" and "shack" mean basically the same thing, but one word has a positive connotation and the other has a negative connotation. Using a loaded term by itself isn't fallacious, but using loaded terms as a basis for an argument is. Using a loaded term to imply that the subject in question is bad when the point of your argument is that it's bad is also another form of Begging the Question.
303[[/folder]]
304
305[[folder:Non Sequitur Fallacy]]
306''NonSequitur'' is a Latin term literally meaning "it does not follow," and is commonly seen in discussions of logic; it's a whole ''class'' of fallacies including Affirmation of the Consequent, Denial of the Antecedent, Undistributed Middle and several others. Broadly, it applies to any argument where the conclusion does not flow naturally from the premises. Non Sequiturs are an important element in humour, but they're still fallacies when used as part of a logical argument.
307
308Often, a non sequitur results from the writer believing that the statement results from an "obvious" argument that doesn't need to be explicitly stated.
309
310For when this ''[[RefugeInAudacity actually works as an argument]]'', see ChewbaccaDefense. When this is to such an extreme that attempts to consider it in any rational manner results in maddening frustration, it is InsaneTrollLogic.
311[[/folder]]
312
313[[folder:Process of Elimination Fallacy]]
314Also called:
315* ''Arcane Explanation''
316* ''Holmesian Fallacy''
317* ''Sherlock Holmes Fallacy''
318
319This fallacy happens when an explanation is considered "correct" after other alternative explanations have been ruled out. It is named for the quote by Franchise/SherlockHolmes from various stories where he says that when one eliminates all which is impossible, whatever is left is the truth no matter how improbable.
320
321For this maxim to work, that means one has to find all possible explanations and eliminate them one by one. This however requires omniscience, can lead to [[InsaneTrollLogic very improbable explanations]] and the real answer may be one that was never considered. If the science behind the right or wrong explanation wasn't known at the time (such as [[ClarkesThirdLaw being considered magic or of the gods]]), see ScienceMarchesOn.
322[[/folder]]
323
324[[folder:Proof by Examples]]
325Also called an inappropriate or hasty generalization or the No Limits Fallacy, this fallacy happens when someone takes one or more non-exhaustive examples from a group that have a property, and making a generalization that everything in that group has that property.
326
327->3 is odd, and it is a prime number.\
32813 is odd, and it is a prime number.\
32997 is odd, and it is a prime number.\
330Therefore, all odd numbers are prime numbers.
331
332Or in other words, this fallacy is about mistaking inductive reasoning for deductive reasoning. A common version is to assume that anything can be extended off to infinity, or that since having a little of something is good, having more must be better. It's a line of thinking commonly used by those talking about future technology.
333
334->"If I told you fifty years ago that you'd have a phone smaller than a deck of cards, that computers would be small enough to put into a pocket, and that your car would be able to call for help if it was involved in a crash, you'd have laughed at me. So if you say that faster-than-light travel is impossible, you're just being small-minded, since technology continues to improve all the time."
335[[/folder]]
336
337[[folder:Prosecutor's Fallacy]]
338Rejecting an explanation for a particular event on the grounds that it requires a rare or unlikely event to have occurred, while ignoring that the favoured explanation might actually be even less likely. This fallacy ignores the fact that 'improbable' doesn't mean 'impossible'. Like the GamblersFallacy, this is also a statistical error.
339
340As the name implies, this fallacy is a favorite of prosecutors in legal cases and sometimes in procedural shows like CSI -- it can be quite tempting to argue, "How likely is it that this really happened the way the defendant said it did, if the odds of it happening that way are 1 in 10 million? Which is more believable -- that he's lying or that something that improbable really happened?" It also lends itself well to CassandraTruth plots.
341
342An argument of this form often ignores that unusual cases are, well, unusual. We tend to notice unusual events more than common events, and the very fact that the issue is being argued over guarantees that it is likely an unusual event. For instance, if a practised hunter accidentally shoots his friend, one could argue that the odds of him making such a serious error is very small. But then, the alternative explanation is that the hunter ''purposefully'' shot his friend, which is also somewhat unlikely. In the end, the event itself can ''only'' be explained by one of several improbable explanations, and so the fact that they ''are'' improbable ceases to be relevant.
343[[/folder]]
344
345[[folder:Retrospective Determinism]]
346Assuming that because something happened it was inevitable; often, the follow-on is a hasty generalisation that it will inevitably happen ''again'' in the same situation, leading to tropes like HitlersTimeTravelExemptionAct and PlanetOfHats.
347
348->Alice: Hey Bob, how's the knee?\
349Bob: After I went out for a walk, I was bound to trip and break my knee.
350
351Bob gives no real reason as to why this was the only possible result, or even why it was the most likely; it differs from FalseCause in that he ''did'' break his knee as a result of going out for a walk. He might follow on by cautioning Alice to avoid going outside, lest she suffer the same fate. Often happens during arguments over AlternateHistory, as someone attempts to argue for the historical result being inevitable.
352
353More seriously, people use this to comfort themselves after losing someone, saying "it was their time." Unless they really believe that each person's time of death is determined beforehand, they don't really mean it (especially as that would be very depressing).
354[[/folder]]
355
356[[folder:Reverse Slippery Slope Fallacy]]
357Arguing that because a slippery slope has failed to appear, further travel down the slope is safe. Note that such arguments can actually legitimize a SlipperySlopeFallacy; the speaker has established a precedent of using previous travel down the slope to justify further travel down the slope; thus, one is justified in worrying that this new action will in turn be used to justify even more actions.
358[[/folder]]
359
360[[folder:Semantic Slippery Slope Fallacy]]
361The Semantic Slippery Slope is a fallacy that occurs when someone argues that because there is no clear line between two concepts or because they "only" differ in degree, they are either the same thing or neither exists at all.
362
363This fallacy is somewhat of an inversion of the FalseDichotomy, in which someone ignores any grey area and posits that only two contrasts exist. The Semantic Slippery Slope emphasizes any grey area and disregards clear differences. In short, saying the concept is too vague for any real decision to be made. The Semantic Slippery Slope Fallacy is also related to the regular SlipperySlopeFallacy insofar as committing the former will often cause the latter by inferring that one thing will inevitably cause the second thing, or that they're the same thing altogether.
364[[/folder]]
365
366[[folder:Shifting the Burden of Proof]]
367Generally in a debate, the negative assumption is taken as the default; in other words, if there is not adequate proof given that something ''does'' happen, it will be taken that it does not. The Burden of Proof Fallacy occurs when an attempt is made to shift this burden to the wrong side. For example:
368
369->''"You can't prove that your house is '''not''' full of invisible landmines, so you'd better stay still in case you accidentally set one off."''
370
371This is a good demonstration of why the negative side doesn't bear the burden of proof; it is for all intents impossible to demonstrate something is absolutely incapable of happening, and it would be impossible to live one's life in light of all the things that might be true. It's far easier to demonstrate proof of the positive (if it exists). Put more simply, if someone has advanced no good reason to believe something is true, believing it is true anyway is unreasonable. This does not necessarily mean it is untrue (see the Fallacy Fallacy), but it does mean it is not logical to believe it is true.
372
373Linguistic trickery can often be used to make a negative appear to be a positive (for example, claim that rejecting the existence of the invisible landmines is a positive claim that "I can explain everything in the universe right now"). It pays to be careful in evaluating which side the burden actually belongs on.
374
375One popular form of shifting the burden of proof is to demand your opponent ‘do their own research’. This places the onus for proving the point you're trying to make onto them. This particularly applies if the research they're supposed to perform is defined extremely vaguely, such as ‘take some classes’, ‘you can find dozens of examples’ or even ‘use common sense’.
376[[/folder]]
377
378[[folder:Special Pleading]]
379This is the fallacy of asking to be given an exemption to a rule that others are held to. It's typically used as [[ScrewThisIndexIHaveTropes an excuse for special treatment others don't receive]], or to win arguments by claiming to have special insights others don't have.
380
381-> "I'm a judge, so I shouldn't have to stop at red lights."
382
383This is fallacious because even if someone has certain expertise or is part of a specific group, they still have to provide evidence and cogent reasons for their position.
384
385Another example could be formulated like this:
386
387-> Everyone has a duty to help the police do their job, no matter who the suspect is. That is why we must support investigations into corruption in the police department. No person is above the law. Of course, if the police come knocking on my door to ask about my neighbors and the robberies in our building, I know nothing. I’m not about to rat on anybody.
388
389In this example, the principle of helping the police is applied to investigations of police officers but not to one’s neighbors.
390[[/folder]]
391
392[[folder:Spotlight Fallacy]]
393
394Also known as misleading vividness or the Volvo Fallacy, this is a close cousin to the Anecdotal Fallacy. The Spotlight Fallacy is making a generalization based on how much news coverage a subject gets. This is fallacious because the news media tends to focus heavily on events that are less common in real life. However, because the news covers them so extensively, it's an easy mistake to make.
395
396It's said that "'Dog Bites Man' is not news; 'Man Bites Dog' is news." Using that example, this trope is when somebody assumes that men biting dogs is more common than the reverse, because it appears in the papers more often.
397
398Compare TheNewRockAndRoll and CowboyBebopAtHisComputer.
399[[/folder]]
400
401[[folder:Stolen Concept]]
402A fallacy in which one or more of the concepts (or premises) on which an argument depends are (usually implicitly) denied by the argument itself, thus meaning the arguer is taking two or more opposed positions at the same time. [[TropeNamer Named]] by Creator/AynRand (and discussed in more detail [[UsefulNotes/{{Objectivism}} here]]). Popular in anti-science literature where scientific processes will be used in an attempt to discredit their own underlying assumptions.
403
404-> "The latest research in zero-point field quantum physics shows that it is possible to make a perpetual motion machine, and that the first law of thermodynamics does not apply in the quantum domain."
405
406Zero-point field theories include conservation of mass / energy as an assumption. They would disprove themselves if they actually made this conclusion.
407
408-> "Quantum physics has proven that reality does not exist objectively." (the less advanced version of the above argument).
409
410The notion of "proof" assumes the objective existence of something to prove in the first place. Additionally, if nothing existed objectively, there would be no reliable methods of proof, including quantum physics.
411[[/folder]]
412
413[[folder:Strawman Fallacy]]
414The [[TheWarOnStraw Strawman Fallacy]] occurs when a debater constructs a more easily defeated version of their opponent's position to attack, rather than addressing their real arguments. The fallacy takes its name from straw dummies used in old-fashioned combat training; these dummies were made to look like a potential opponent, but provide no actual resistance. The fallacy itself is comparable to defeating such a dummy, then proclaiming you have defeated an actual opponent.
415
416-> ''"The NRA supports the right to bear arms, so they support private ownership of nuclear weapons."''
417
418While most people will not be fooled by a blatant misrepresentation of their position, careful use of a strawman can make them defend a carefully undermined version of their position, allowing their opponent to apparently destroy them with a prepared rebuttal. However, it's more often used to get the ''audience'' on one's side than it is to confuse the opponent, especially when it's coupled with an AdHominem implying that the opponent is immoral for "holding" the strawmanned position.
419
420The opposite is called the Steelman, where one argues against the ''best'' possible version of an opponent's position.
421[[/folder]]
422
423[[folder:Two Negative Premises]]
424If A is not B, and B is not C, then A is C. This is always invalid logic (although it may happen to be true), as it is not possible to make a valid conclusion from two negative premises; logic is not arithmetic. This is a fallacy because simply identifying what something ''isn't'' doesn't identify what it ''is''.
425
426-> No Jews are Muslims.\
427No Muslims are Christians.\
428Therefore Jews are Christians.
429
430-> No dogs are reptiles.\
431No reptiles are magenta.\
432Dogs are magenta.
433
434-> No dogs are reptiles.\
435No reptiles shoot lasers out of their eyes.\
436Dogs shoot lasers out of their eyes.
437[[/folder]]
438
439[[folder:Undistributed Middle]]
440This fallacy occurs when the middle term of a standard three-step syllogism is not distributed[[note]] a distributed premise is one that gives you information on at least one entire class of things, eg. "all penguins are birds", but not "some birds are penguins" - consult logic textbooks[[/note]] in either premise. [[https://static.tvtropes.org/pmwiki/pub/images/3912.jpg This picture]] is a case of undistributed middle. Using that image, "black and white" is the middle term, the term that appears in both premises; it is undistributed because neither premise refers to ''all'' things that are "black and white". Newspapers are black and white as well, and they are neither penguins nor old TV shows. "Things that are black and white" is the superset, and it contains many subsets that do not overlap at all. In casual use, undistributed middle can be hard to spot.
441
442-> Liberals always want to raise taxes.\
443Alice says that she's a conservative, but she also says that the sales tax needs to be raised.\
444She's lying about being a conservative; she's really a liberal.
445
446The point is not how "liberal" and "conservative" are defined; it's that at no point is it established that only liberals want to raise taxes. Put another way, saying "All liberals are people who want to raise taxes" is not the same as saying "All people who want to raise taxes are liberals."
447[[/folder]]

Top