TagLast edit: 1 Oct 2020 22:45 UTC by Ruby

A fallacy is generally considered to be an error in reasoning. It refers both to the failure to apply logic to a line of thought, and to the use of problematic arguments. The term can be applied when dealing both with informal and formal logic, although it usual refers to the former.

Related: Disagreement, Heuristics & Biases

Informal vs Formal Fallacy

An informal fallacy refers to a flawed argument, where the premises do not support the conclusion. It can, however, have a valid logical format. This type of fallacy is commonly divided in two main groups: material fallacies and verbal fallacies.

Material fallacies, concerned with the content of the argument, can be divivided following Aristotle’s taxonomy from his work Organon. One such example is the famous Straw Man fallacy:

  1. Person A has position X: We should focus our efforts on Friendly AI research.

  2. Person B distorts position X to something close, but different, Y: So you think we should just give up on webdesign?!

  3. Person B attacks position Y: That’s stupid, websites are such a great way of spreading information!

Verbal fallacies, on the other hand, deal with the way the words are used. These include examples such as Equivocation—using words ambiguously or with double meanings—and Proof by Verbosity, where one overwhelms his listener with lots of material in an complicated way.

A formal fallacy, contrasting with informal fallacies, refers to a pattern of reasoning which is wrong due to a flaw in the logical structure of the argument. As such, this deductive fallacy does not imply any information about the premises or the conclusion—its their connection that’s wrongly stated. Both can be correct and the argument can be wrong because the conclusion doesn’t follow from the premises as it is said to.

False Fallacies & Awareness

Matters can be further complicated by arguing parties incorrectly claiming that an assertion is false due to a fallacy. For example, if one party was to declare “Albert Einstein has claimed that time and space are relative qualities of the Universe.”, another party might responded by saying that this is an ’’’argument from authority’’’. However, Albert Einstein’s claims are based on detailed mathematical models that identify him as an expert in this field of inquiry, rather than a casual observer. We are thus facing a kind of meta-fallacy which is wrong by itself.

Recognizing fallacies in everyday arguments can be difficult due to complicated patterns of communication that mask the logical connections between statements. At the same time, informal fallacies can also take advantage of the emotional or psychological weaknesses of the listener. It is thus important to develop the ability to recognize them in arguments, so as to reduce the likelihood of being tricked or cheated. This ability becomes even more important when dealing with today’s mass media, where the intention is to influence behavior and change beliefs, from political campaigns to simple local newspapers.

Further Reading & References

See Also

Know­ing About Bi­ases Can Hurt People

Eliezer Yudkowsky4 Apr 2007 18:01 UTC
197 points
82 comments2 min readLW link

Con­junc­tion Fallacy

Eliezer Yudkowsky19 Sep 2007 1:54 UTC
48 points
46 comments3 min readLW link

Prov­ing Too Much

Scott Alexander14 Apr 2013 0:05 UTC
108 points
4 comments2 min readLW link

The Fal­lacy of Gray

Eliezer Yudkowsky7 Jan 2008 6:24 UTC
272 points
81 comments5 min readLW link

The non­cen­tral fal­lacy—the worst ar­gu­ment in the world?

Scott Alexander27 Aug 2012 3:36 UTC
407 points
1,768 comments7 min readLW link

The Third Alternative

Eliezer Yudkowsky6 May 2007 23:47 UTC
144 points
84 comments3 min readLW link

Mind Pro­jec­tion Fallacy

Eliezer Yudkowsky11 Mar 2008 0:29 UTC
76 points
90 comments2 min readLW link

The Log­i­cal Fal­lacy of Gen­er­al­iza­tion from Fic­tional Evidence

Eliezer Yudkowsky16 Oct 2007 3:57 UTC
121 points
62 comments6 min readLW link

Defend­ing the non-cen­tral fallacy

Matthew Barnett9 Mar 2021 21:42 UTC
133 points
38 comments6 min readLW link

Gen­er­al­iz­ing From One Example

Scott Alexander28 Apr 2009 22:00 UTC
430 points
422 comments6 min readLW link

Bur­den­some Details

Eliezer Yudkowsky20 Sep 2007 23:46 UTC
215 points
44 comments4 min readLW link

Plan­ning Fallacy

Eliezer Yudkowsky17 Sep 2007 7:06 UTC
171 points
43 comments3 min readLW link

The Truth about Scots­men, or: Dis­solv­ing Fallacies

Tesseract5 Dec 2010 21:57 UTC
37 points
36 comments3 min readLW link

A Teacher vs. Every­one Else

ronak6921 Mar 2024 17:45 UTC
40 points
8 comments2 min readLW link

What cog­ni­tive bi­ases feel like from the inside

chaosmage3 Jan 2020 14:24 UTC
249 points
32 comments4 min readLW link

The Ge­netic Fallacy

Eliezer Yudkowsky11 Jul 2008 5:47 UTC
65 points
18 comments3 min readLW link

Ar­gu­ment by In­tel­lec­tual Ordeal

lc12 Aug 2022 13:03 UTC
26 points
5 comments5 min readLW link

The Com­plete Idiot’s Guide to Ad Hominem

Eliezer Yudkowsky25 Nov 2008 21:47 UTC
14 points
16 comments1 min readLW link

Fal­la­cies as weak Bayesian evidence

Kaj_Sotala18 Mar 2012 3:53 UTC
87 points
42 comments10 min readLW link

I Was Not Al­most Wrong But I Was Al­most Right: Close-Call Coun­ter­fac­tu­als and Bias

Kaj_Sotala8 Mar 2012 5:39 UTC
86 points
40 comments9 min readLW link

Car­diol­o­gists and Chi­nese Robbers

Scott Alexander16 Sep 2015 19:00 UTC
136 points
8 comments6 min readLW link

The Haters Gonna Hate Fallacy

Kaj_Sotala22 Sep 2020 12:20 UTC
47 points
6 comments1 min readLW link

Log­i­cal Foun­da­tions of Govern­ment Policy

FCCC10 Oct 2020 17:05 UTC
2 points
0 comments17 min readLW link

Your in­tu­itions are not magic

Kaj_Sotala10 Jun 2010 0:11 UTC
163 points
42 comments4 min readLW link

Talk­ing Snakes: A Cau­tion­ary Tale

Scott Alexander13 Mar 2009 1:41 UTC
185 points
232 comments3 min readLW link

Pain is not the unit of Effort

alkjash24 Nov 2020 20:00 UTC
517 points
89 comments5 min readLW link2 reviews

Catchy Fal­lacy Name Fal­lacy (and Sup­port­ing Disagree­ment)

JGWeissman21 May 2009 6:01 UTC
33 points
57 comments2 min readLW link

Fu­sion and Equiv­o­ca­tion in Korzyb­ski’s Gen­eral Semantics

abramdemski21 Dec 2020 5:44 UTC
65 points
14 comments3 min readLW link

Safe Sta­sis Fallacy

Davidmanheim5 Feb 2024 10:54 UTC
54 points
2 comments1 min readLW link

[Question] Can So­cial Dy­nam­ics Ex­plain Con­junc­tion Fal­lacy Ex­per­i­men­tal Re­sults?

curi5 Aug 2020 8:50 UTC
8 points
8 comments1 min readLW link

Black ravens and red herrings

Matthew Barnett27 Jul 2021 17:46 UTC
50 points
17 comments1 min readLW link

Trust and The Small World Fallacy

DPiepgrass4 Oct 2021 0:38 UTC
26 points
14 comments14 min readLW link

[Question] Worst Com­mon­sense Con­cepts?

abramdemski15 Nov 2021 18:22 UTC
73 points
34 comments3 min readLW link

Re­sist the Happy Death Spiral

Eliezer Yudkowsky4 Dec 2007 1:15 UTC
84 points
45 comments6 min readLW link

[Question] What’s the name of this fal­lacy/​rea­son­ing an­tipat­tern?

David Gross18 Jun 2022 14:04 UTC
9 points
6 comments1 min readLW link

Law of No Evidence

Zvi20 Dec 2021 13:50 UTC
121 points
19 comments4 min readLW link1 review

Bayesi­ans Com­mit the Gam­bler’s Fallacy

Kevin Dorst7 Jan 2024 12:54 UTC
46 points
28 comments8 min readLW link

Where the log­i­cal fal­lacy is not (Gen­er­al­iza­tion From Fic­tional Ev­i­dence)

banev11 Nov 2022 10:41 UTC
−12 points
14 comments1 min readLW link

The Statis­ti­cian’s Fallacy

ChrisHallquist9 Dec 2013 4:48 UTC
63 points
69 comments3 min readLW link

Senses of “know­ing” a person

dkl918 Feb 2024 19:13 UTC
3 points
0 comments1 min readLW link

[Question] Alice and Bob is de­bat­ing on a tech­nique. Alice says Bob should try it be­fore deny­ing it. Is it a fal­lacy or some­thing similar?

Ooker17 Mar 2024 20:01 UTC
0 points
19 comments2 min readLW link

The salt in pasta wa­ter fallacy

Thomas Sepulchre27 Mar 2023 14:53 UTC
157 points
38 comments3 min readLW link

[Question] look­ing for name/​fur­ther read­ing on fal­lacy I came across

Yitz28 May 2020 18:01 UTC
1 point
1 comment1 min readLW link

Lin­ear­ity Fallacies

hippo15 Nov 2023 2:23 UTC
15 points
0 comments5 min readLW link

Hind­sight De­val­ues Science

Eliezer Yudkowsky17 Aug 2007 19:39 UTC
228 points
43 comments2 min readLW link

The Typ­i­cal Sex Life Fallacy

ozymandias7 Oct 2017 21:48 UTC
38 points
30 comments5 min readLW link

Make your train­ing useful

AnnaSalamon12 Feb 2011 2:14 UTC
134 points
46 comments5 min readLW link

The Ep­silon Fallacy

johnswentworth17 Mar 2018 0:08 UTC
87 points
20 comments7 min readLW link

The Pas­cal’s Wager Fal­lacy Fallacy

Eliezer Yudkowsky18 Mar 2009 0:30 UTC
44 points
128 comments3 min readLW link

Dialogue on Ap­peals to Consequences

jessicata18 Jul 2019 2:34 UTC
33 points
82 comments7 min readLW link

Hy­po­thet­i­cals: The Direct Ap­pli­ca­tion Fallacy

Chris_Leong9 May 2018 14:23 UTC
21 points
19 comments4 min readLW link

Surely, rhetor­i­cal ques­tion?

Gust11 Jan 2018 20:56 UTC
15 points
0 comments1 min readLW link

The Sally-Anne fallacy

philh11 Apr 2016 13:06 UTC
64 points
20 comments1 min readLW link

Three Fal­la­cies of Teleology

Eliezer Yudkowsky25 Aug 2008 22:27 UTC
36 points
14 comments9 min readLW link

Mul­ti­ple stages of fal­lacy—jus­tifi­ca­tions and non-jus­tifi­ca­tions for the mul­ti­ple stage fallacy

AronT13 Jun 2023 17:37 UTC
33 points
2 comments5 min readLW link

Flow­sheet Logic and Note­card Logic

moridinamael9 Sep 2015 16:42 UTC
46 points
28 comments3 min readLW link

The Par­tial Con­trol Fallacy

Darmani14 Dec 2016 2:57 UTC
28 points
2 comments2 min readLW link

[Question] Is Stu­pidity Ex­pand­ing? Some Hy­pothe­ses.

David Gross15 Oct 2020 3:28 UTC
71 points
42 comments5 min readLW link

Imag­i­nary Positions

Eliezer Yudkowsky23 Dec 2008 17:35 UTC
30 points
49 comments3 min readLW link

The Fal­lacy of Dress­ing Like a Winner

benelliott26 Dec 2010 20:59 UTC
27 points
21 comments6 min readLW link

Why *I* fail to act rationally

bentarm26 Mar 2009 3:56 UTC
15 points
23 comments1 min readLW link

How Not to be Stupid: Start­ing Up

Psy-Kosh28 Apr 2009 0:23 UTC
13 points
5 comments1 min readLW link

The Fal­lacy of Large Numbers

dspeyer12 Aug 2012 18:39 UTC
30 points
31 comments2 min readLW link

The Onion Goes In­side The Bi­ased Mind

patrissimo30 May 2009 17:33 UTC
8 points
3 comments1 min readLW link

Avoid­ing Failure: Fal­lacy Finding

Patrick3 Jul 2009 17:59 UTC
14 points
19 comments1 min readLW link

The Case for Log­i­cal Fallacies

Aaron Bergman8 Mar 2021 3:04 UTC
14 points
0 comments7 min readLW link

Ir­ra­tional ar­gu­ments or valuable heuris­tics?

Hauntology Ph.D.8 Mar 2021 5:34 UTC
8 points
0 comments8 min readLW link

The case for hypocrisy

Aaron Bergman13 May 2021 3:36 UTC
37 points
12 comments5 min readLW link

Does but­terfly af­fect?

pchvykov14 May 2021 4:20 UTC
14 points
21 comments2 min readLW link

The Moun­taineer’s Fallacy

Alex Power17 Jul 2021 23:45 UTC
29 points
11 comments1 min readLW link

[Question] Liv­ing with a home­opath—how?

sudoLife21 Aug 2021 12:41 UTC
5 points
36 comments1 min readLW link