Con­junc­tion Fallacy

TagLast edit: 3 Oct 2020 0:21 UTC by Swimmer963 (Miranda Dixon-Luinenburg)

The conjunction fallacy consists in assuming that specific conditions are more probable than more general ones.

For the reasons related to representativeness heuristic, a fleshed-out story that contains typical amount of detail sounds more plausible than a stripped-down description of a situation that only states a few facts. There is a tendency for people to take that plausibility at face value, and assign probability accordingly. This intuition is wrong, because the conjunction rule of probability theory states that, for any event X, its conjunction with additional details Y will be less probable.

The conjunction fallacy suggests that one should be very careful in adding details to any claim, as even though each such detail may make the claim so much more convincing, it also inevitably subtracts from its validity.

Blog posts

See also

Disjunc­tions, An­tipre­dic­tions, Etc.

Eliezer Yudkowsky9 Dec 2008 15:13 UTC
28 points
26 comments5 min readLW link

Con­junc­tion Con­tro­versy (Or, How They Nail It Down)

Eliezer Yudkowsky20 Sep 2007 2:41 UTC
58 points
25 comments8 min readLW link

Con­junc­tion fal­lacy and prob­a­bil­is­tic risk as­sess­ment.

Dmytry8 Mar 2012 15:07 UTC
26 points
10 comments2 min readLW link

[SEQ RERUN] Con­junc­tion Fallacy

MinibearRex1 Sep 2011 2:19 UTC
11 points
0 comments1 min readLW link

[Link] Us­ing the con­junc­tion fal­lacy to re­veal im­plicit associations

HonoreDB6 Dec 2011 17:29 UTC
7 points
5 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

Asch Con­for­mity Could Ex­plain the Con­junc­tion Fallacy

curi6 Aug 2020 21:46 UTC
7 points
1 comment5 min readLW link

The Law of Least Effort Con­tributes to the Con­junc­tion Fallacy

curi9 Aug 2020 19:38 UTC
7 points
53 comments3 min readLW link

About Less Wrong

Eliezer Yudkowsky23 Feb 2009 23:30 UTC
57 points
3 comments2 min readLW link

Bur­den­some Details

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

Which cog­ni­tive bi­ases should we trust in?

Andy_McKenzie1 Jun 2012 6:37 UTC
29 points
42 comments3 min readLW link

Con­junc­tion Fallacy

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

ChatGPT challenges the case for hu­man irrationality

Kevin Dorst22 Aug 2023 12:46 UTC
3 points
10 comments7 min readLW link
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