Quick Question: What's the formal name of this fallacy?
- labarith
- New Trial Member
- Posts: 5
- Joined: June 13th, 2022, 7:09 pm
Quick Question: What's the formal name of this fallacy?
I'll try to describe it as best I can. The author begins with a case and says a disjunction is (a v b) is true of the case, then constructs a separate case in which the first option a is not an option, thereby concluding b must be true of both cases.
Here's an example (other than the one the author uses):
Case 1: Jane is wearing a blue dress.
In this case, the following proposition p is true: (Jane is wearing a dress OR Brown is in Barcelona)
Case 2: Jane is not wearing a dress.
Therefore, in case 2, Brown is in Barcelona.
- Pattern-chaser
- Premium Member
- Posts: 8265
- Joined: September 22nd, 2019, 5:17 am
- Favorite Philosopher: Cratylus
- Location: England
Re: Quick Question: What's the formal name of this fallacy?
This case, as described, appears valid. If the premise is correct (and it probably wouldn't be, in practice), and Jane is not wearing a dress, then Brown is in Barcelona. I see no fallacy here. Perhaps a better example might offer better understanding?
"Who cares, wins"
- labarith
- New Trial Member
- Posts: 5
- Joined: June 13th, 2022, 7:09 pm
Re: Quick Question: What's the formal name of this fallacy?
Proposition p is true of case 1 (because Jane *is* wearing a dress), but there is no reason to think it's true for case 2.
(These are both fictional cases, and the cases denote all we know about those worlds.)
- Thomyum2
- Posts: 366
- Joined: June 10th, 2019, 4:21 pm
- Favorite Philosopher: Robert Pirsig + William James
Re: Quick Question: What's the formal name of this fallacy?
I'm not sure there is a name specifically for this particular type of fallacy, but it would be considered a formal fallacy and a type of non sequitur. It's sort of a variation on the fallacy of denying the antecedent, but I think it's probably better classified as a fallacy of an affirmative conclusion from a negative premise.labarith wrote: ↑June 13th, 2022, 7:19 pm I came across a fallacy in a recent article but for the life of me I can't think of the formal term for the fallacy. Any help would be appreciated.
I'll try to describe it as best I can. The author begins with a case and says a disjunction is (a v b) is true of the case, then constructs a separate case in which the first option a is not an option, thereby concluding b must be true of both cases.
Here's an example (other than the one the author uses):
Case 1: Jane is wearing a blue dress.
In this case, the following proposition p is true: (Jane is wearing a dress OR Brown is in Barcelona)
Case 2: Jane is not wearing a dress.
Therefore, in case 2, Brown is in Barcelona.
— Epictetus
-
- Posts: 4696
- Joined: February 1st, 2017, 1:06 am
Re: Quick Question: What's the formal name of this fallacy?
You haven't put those in the form of a proper argument. Is there one argument there, or two? If it is all one argument, then it is self-contradictory (Jane both is and is not wearing a blue dress). If "Case 2" is a separate argument, then it is simply a non-sequitur, since there is no premise involving Brown.labarith wrote: ↑June 13th, 2022, 7:19 pm I came across a fallacy in a recent article but for the life of me I can't think of the formal term for the fallacy. Any help would be appreciated.
I'll try to describe it as best I can. The author begins with a case and says a disjunction is (a v b) is true of the case, then constructs a separate case in which the first option a is not an option, thereby concluding b must be true of both cases.
Here's an example (other than the one the author uses):
Case 1: Jane is wearing a blue dress.
In this case, the following proposition p is true: (Jane is wearing a dress OR Brown is in Barcelona)
Case 2: Jane is not wearing a dress.
Therefore, in case 2, Brown is in Barcelona.
- labarith
- New Trial Member
- Posts: 5
- Joined: June 13th, 2022, 7:09 pm
Re: Quick Question: What's the formal name of this fallacy?
The cases are distinct.GE Morton wrote: ↑June 14th, 2022, 9:29 pm You haven't put those in the form of a proper argument. Is there one argument there, or two? If it is all one argument, then it is self-contradictory (Jane both is and is not wearing a blue dress). If "Case 2" is a separate argument, then it is simply a non-sequitur, since there is no premise involving Brown.
Of case 1, the author says either (a v b) is true. As it so happens, it is true because a is true.
However, the author wants to argue b to be true, not a. So they construct case 2, which is exactly like case 1, except a is not true. The author, then, concludes "Well, (a v b) was true in case 1, a is not an option in case 2, so b must be true in case 2."
I've never come across a mistake like this and wondered if there was any precedent or examples I could call out to succinctly explain the fallacy.
In any case, thanks to everyone who replied.
-
- Posts: 4696
- Joined: February 1st, 2017, 1:06 am
Re: Quick Question: What's the formal name of this fallacy?
The "cases" may be distinct, but what the argument is, is unclear. Only logical fallacies have "formal names," and they only apply to logical arguments.labarith wrote: ↑June 14th, 2022, 10:14 pmThe cases are distinct.GE Morton wrote: ↑June 14th, 2022, 9:29 pm You haven't put those in the form of a proper argument. Is there one argument there, or two? If it is all one argument, then it is self-contradictory (Jane both is and is not wearing a blue dress). If "Case 2" is a separate argument, then it is simply a non-sequitur, since there is no premise involving Brown.
You need to dispense with the "cases" and re-formulate the question as an argument, with premises and a conclusion.
- labarith
- New Trial Member
- Posts: 5
- Joined: June 13th, 2022, 7:09 pm
Re: Quick Question: What's the formal name of this fallacy?
1. In case 1 (a v b)GE Morton wrote: ↑June 15th, 2022, 12:44 pmThe "cases" may be distinct, but what the argument is, is unclear. Only logical fallacies have "formal names," and they only apply to logical arguments.labarith wrote: ↑June 14th, 2022, 10:14 pmThe cases are distinct.GE Morton wrote: ↑June 14th, 2022, 9:29 pm You haven't put those in the form of a proper argument. Is there one argument there, or two? If it is all one argument, then it is self-contradictory (Jane both is and is not wearing a blue dress). If "Case 2" is a separate argument, then it is simply a non-sequitur, since there is no premise involving Brown.
You need to dispense with the "cases" and re-formulate the question as an argument, with premises and a conclusion.
2. In case 2 ~a.
Conclusion: Therefore b. (of all cases at all times)
Of course, the author wants us to read it as:
1. a v b
2. ~a
C: Therefore, b.
The latter argument, of course, is valid. The former is not, but I'm not sure if there's a formal name for this particular logical error.
I don't *think* this counts as a generalization fallacy, as the problem isn't merely that the author is making a conclusion about the whole based on a conclusion about a single specific case, but rather turns on confusion about the disjunction as well.
- Pattern-chaser
- Premium Member
- Posts: 8265
- Joined: September 22nd, 2019, 5:17 am
- Favorite Philosopher: Cratylus
- Location: England
Re: Quick Question: What's the formal name of this fallacy?
Yes, there is. You stated that
Since p is true, then either Jane is wearing a dress or Brown is in Barcelona. We know that Jane isn't wearing a dress, and that p is true, so Brown is in Barcelona.
"Who cares, wins"
-
- Posts: 4696
- Joined: February 1st, 2017, 1:06 am
Re: Quick Question: What's the formal name of this fallacy?
The former is the same argument, and is also valid. The "in case" adds nothing to it. And the "all cases at all times" doesn't apply; for that you'd need quantifiers on your variables.labarith wrote: ↑June 15th, 2022, 1:17 pm
1. In case 1 (a v b)
2. In case 2 ~a.
Conclusion: Therefore b. (of all cases at all times)
Of course, the author wants us to read it as:
1. a v b
2. ~a
C: Therefore, b.
The latter argument, of course, is valid. The former is not, but I'm not sure if there's a formal name for this particular logical error.
- labarith
- New Trial Member
- Posts: 5
- Joined: June 13th, 2022, 7:09 pm
Re: Quick Question: What's the formal name of this fallacy?
Perhaps it's best to back to our original example.GE Morton wrote: ↑June 15th, 2022, 10:35 pmThe former is the same argument, and is also valid. The "in case" adds nothing to it. And the "all cases at all times" doesn't apply; for that you'd need quantifiers on your variables.labarith wrote: ↑June 15th, 2022, 1:17 pm
1. In case 1 (a v b)
2. In case 2 ~a.
Conclusion: Therefore b. (of all cases at all times)
Of course, the author wants us to read it as:
1. a v b
2. ~a
C: Therefore, b.
The latter argument, of course, is valid. The former is not, but I'm not sure if there's a formal name for this particular logical error.
Case 1: Jane is wearing a dress. Brown exists, but we know not where.
If Case 1 is true, then we know proposition:
[*] (p1) Jane is wearing a dress.
Now, as Gettier notes, if we know the truth of some proposition a, we know the disjunction (a v b).
With regards to case 1, we know [Jane is wearing a dress], therefore we know the following disjunctions:
[*] (p2) Either Jane is wearing a dress, or Brown is in Boston.
[*] (p3) Either Jane is wearing a dress, or Brown is in Barcelona.
[*] (p4) Either Jane is wearing a dress, or Brown is in Brest-Litovsk.
Now, consider Case 2:
Case 2: Jane is not wearing a dress. Brown exists, but we know not where.
Of course, for any given proposition ~(p & ~p), so if Jane is wearing a dress in Case 1 and Jane is not wearing a dress in Case 2, then either Jane1 and Jane2 are different people, or Case 1 and Case 2 occur at different times (such that @ during the period of time described in Case 1, Jane is wearing a dress, and during the period of time described in Case 2, Jane is not wearing a dress. In either of these cases, there is no contradiction, but there is also no reason to think that what we say of case 1, proposition (p3) is true of Case 2.
Of course these are hypothetical cases; there is no Jane, no Jane1, no Jane2, no Brown. However, we can still analyze the cases. We can say "If Case 1 were real, then proposition (p1) is true, as is propositions (p2)-(p4).
However, just because (p3) is true of Case 1 is no reason to think (p3) is true of case 2. For example:
Case 3: Adam was born in the year 2000 and attended the Oscars in 2020 and won an Oscar award.
Case 4: Adam was born in the year 1000 and never won any awards.
The following proposition is true of case 3, but not of case 4:
[*] (p5) Adam won an award.
Any confusion regarding the truth or falsity of (p5) comes from ambiguity in which "Adam", which case, the proposition is meant to describe; (p5) is true of Case 3, but then the author - in this case me - specifically changed the scenario described in case 4 so that (p5) would not be true. This is not unusual (For example, consider James Rachels' parallel cases, or David Boonin's Bone Marrow thought experiments).
What is unusual (about the arguments I'm discussing, from a punished author I don't want to besmirch here) is that the author uses a disjunctive proposition about case 1, and treats it as if it is applicable to case 2... despite case 2 being designed to rule out one side of the disjunction (not unlike how my case 4 is designed to rule out the truth of (p5).
Final thought: Perhaps this would have been easier to convey through symbolic logic; is so I apologize for wasting your time.
2023/2024 Philosophy Books of the Month
Mark Victor Hansen, Relentless: Wisdom Behind the Incomparable Chicken Soup for the Soul
by Mitzi Perdue
February 2023
Rediscovering the Wisdom of Human Nature: How Civilization Destroys Happiness
by Chet Shupe
March 2023