Talk:Logical fallacy

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This logic related article has been awarded SILVER status for quality. We like it, and you should too! See RationalWiki:Article rating for more information.

Editorial notes
  • Main article on a wider subject.
  • Better organisation of the list required.

Archives for this talk page: <1>, (new)

Title headings[edit]

Hi, I've noticed some title headings have deviated from the original format found on Fallacy Files and I'm wondering if these extensions are necessary or even helpful. Unfortunately I often find myself reminding people that elaboration rarely equals clarification and it seems some select headings have mutated against this principle. For example, to my mind, "Non-enthymematic Propositional fallacies or Inconsistencies" may serve simply as "Propositional fallacies" in accordance with the FF taxonomy. These mutations are particularly glaring when contrasted with most other headings, which remain concise. Thanks. (talk) 14:52, 8 January 2019 (UTC)

About the (possible) "read all the books" or "appeal to accomplishment" fallacy[edit]

Hi, if anyone can do it, I think there should be an entry on something like the "read all the books" fallacy (if it is how it should be called) as discussed in Thanks. Gquenot (talk) 12:02, 7 July 2019 (UTC)

Example of logical fallacy is wrong[edit]

"One may be wrong in how one arrived at a conclusion, but that doesn't mean the conclusion itself is wrong. It may be true based on some other premise or logical conclusion. For example, one may say:"
P1: Bears have four legs.
P2: All three legged animals are mammals.
C: Therefore a bear is a mammal.

I think P2 was supposed to have in it: four legs, not three :D As for this example of logical fallacy: someone arrived to C, because P1 and than P2. Which in current state make 0 sense! Because there is no other premise, from which you could deduce: bears are mammals. Therefore P2 should be: All four legged animals are mammals. — Unsigned, by: Empleat / talk / contribs

Not really. Just because P2 is false, doesn't mean that C is false.
Also, sign your posts with ~~~~ (four tildes). ElectrosPardon? 17:32, 10 November 2020 (UTC)
In fact I get what you are saying. I will update the article to focus more on how sound the argument is rather than the false premise. ShabiDOO 17:57, 10 November 2020 (UTC)
I agree, the fallacy should be in assuming that all 4 legged animals are mammals (which would include iguanas and frogs), but just because not all 4 legged animals are mammals doesn't mean the conclusion that bears is mammals is wrong even though the logic is flawed. CoryUsar (talk) 20:02, 10 November 2020 (UTC)
No the problem was that the argument only contained a false premise (that all three legged animals were mammals). The argument however was sound and shouldn't have been. I adjusted it so that it contained a strange and false premise AND that the argument isn't sound (it doesn't logically follow). ShabiDOO 22:30, 10 November 2020 (UTC)

Base rate fallacy and statistics (says a footnote)[edit]

The footnote statement that statistical inference is the only mathematically valid way to determine guilt or innocence is kind of ridiculous. OK, sure, but that's a lot like saying analytic chemistry is the only valid way to figure out the tasty ingredient in that dish you ate at the restaurant last night. Statistical inference is about estimating a population parameter or making a probabilistic statement about a hypothesis. It is NOT about determine truth/falsehood. Should I only use calculus to determine how much I should press my brake pedal? Should I rely only on neuroscience to decide whether my joke is funny?

Furthermore, the legalistic examples under base rate fallacy are really poor examples. The most common examples are of population disease testing -- very relevant these days. Another good one might be of crime among various demographic subgroups.

[end rant mode] — Unsigned, by: 2601:285:8380:1ac8:19ad:4754:541d:3841 / talk / contribs

Expanding on my comments as a BoN,
1) The two legalistic examples under "base rate fallacy" are not actually base rate fallacies. They are, if anything, misunderstanding of conditional probabilities and the appropriateness of inference based on those probabilities.
2) Although not base-rate fallacies, they do involve some of the same probabilities involved in Bayes rule so, yeah, mistakes are understandable.
3) Bayes rule has several terms that are explicit or implicit: P[A] and P[B], the marginal probabilities; P[A|B] and P[B|A], the conditional probabilties; and P[A,B] (the numerator of Bayes equation when multiplied out), the join probability of A and B. The base-rate fallacy refers to one, and only one, of the marginals. The legalistic examples (prosecutors and defense fallacies) are a grab bag that emphasize the incorrect use of a conditional or joint probability when a different conditional probability is preferred.
4) There are other examples within the prosecutors/defense fallacies that fall outside the realm of Bayes rule.
5) The current text under base-rate fallacy includes dramatic and unclear statements about "blaming the victim" (a consequence of the fallacy and not the actual fallacy), "blindly trusting the accuser" (a hyped up, imprecise way to incorrectly point to the marginal probability), "blah blah importance of Bayes inference" (true, but a weakness of the judicial system and not a fallacy), "ipse dixit" (nope, not the fallacy you're looking for). As such, they are interesting things, but NOT good or relevant discussions of the fallacy
1) The fallacy should be more directly and clearly described as in the entire syllogistic fallacy section;
2) Irrelevant, but interesting, commentary about the justice system should either be purged or exiled to footnotes. I prefer a purge.

MarmotHead (talk) 00:22, 8 December 2020 (UTC) (currently, a grump)


Let's Make Ratwiki Silver Again! Core (pester) 19:29, 22 March 2021 (UTC)