Logical Fallacy Game

[linford86]

Can we post informal fallacies? If so, here's one:

Marijuana is completely natural (it's a plant!)
Anything that is completely natural is good (or healthy.)
Therefore, marijuana is good (or healthy.)

Fallacy of Accident?

http://www.fallacyfiles.org/accident.html

Nope! Any other takers?

Paris, the game is to stop logical fallacies. We all know that the argument I gave was bad (that's part of the game); the point is to find the fallacy type being committed. I could have, for example, made an argument like:

Smeggles are natural.
Anything that is completely natural is good.
Therefore, smeggles are good.

And the same fallacy would have been committed despite the fact that I have no idea what a smeggle is since it's a non-sense word I just invented.

[Paris]

Paris, the game is to stop logical fallacies. We all know that the argument I gave was bad (that's part of the game); the point is to find the fallacy type being committed. I could have, for example, made an argument like:

Smeggles are natural.
Anything that is completely natural is good.
Therefore, smeggles are good.

And the same fallacy would have been committed despite the fact that I have no idea what a smeggle is since it's a non-sense word I just invented.

The only fallacy that I see here is that even if the first premise "Smeggles are natural" was true, the second premise "Anything that is completely natural is good" certainly isn't.

Therefore the conclusion "smeggles are good" is not guaranteed.

I would call it as the "Conclusion from False Premises" fallacy. I do not have a mental list of the formal names of fallacies.

The concept is what is important. Not the label.

By the way, this is one of the most common types of fallacy.

[mtbturtle]

Fallacy of Accident?

http://www.fallacyfiles.org/accident.html

Nope! Any other takers?

hmmm you did say an informal fallacy?...

http://www.fallacyfiles.org/inforfal.html

An informal fallacy is one that is not formal, that is, it is a type of fallacy in which the content of the argument is relevant to its fallaciousness, or which is fallacious for epistemological, dialectical, or pragmatic reasons. Typically, informal fallacies occur in non-deductive reasoning, which relies on content as well as form for cogency. Also, because content is important in informal fallacies, there are arguments with the form of the fallacy which are cogent. For this reason, when forms for informal fallacies are given, this is for identification purposes only, that is, one cannot tell from the form alone that an instance is fallacious. Rather, the forms will help to differentiate between distinct types of informal fallacy.
Subfallacies:

* Accident
* Ambiguity
* Appeal to Ignorance
* Begging the Question
* Black-or-White Fallacy
* Composition
* Division
* Gambler's Fallacy
* Non Causa Pro Causa
* One-Sidedness
* Red Herring Fallacy
* Special Pleading
* Vagueness
* Weak Analogy

Paris a good list of fallacies can be found here - http://www.fallacyfiles.org

[linford86]

I would call it as the "Conclusion from False Premises" fallacy. I do not have a mental list of the formal names of fallacies.

The concept is what is important. Not the label.

I'm sorry but you have fundamentally misunderstood the game. This thread is the "logical fallacy game" thread. The point is to point out the formal name of each fallacy. And this fallacy is not named "conclusion from false premises".

[Paris]

I'm sorry but you have fundamentally misunderstood the game. This thread is the "logical fallacy game" thread. The point is to point out the formal name of each fallacy. And this fallacy is not named "conclusion from false premises".

Based on previous replies from other participants, I thought that it would be enough to find the fallacy, locate it precisely and describe its type. I am usually most interested on the substance ( concept ) than what wraps it ( a label ).

I apologize, linford86. I misunderstood the game.

[Forest_Dump]

To be honest, I am a bit more with Paris' original point because, of some of the texts, etc., that I checked, they don't all list the same fallacies or define or label them the same. Is there supposed to be a single list and set of definitions? Or would that be misplaced concreteness? Don't get me wrong - I think this is useful and informative stuff.

[xcthulhu]

I also don't see what is wrong with Paris' original post. Knowing the name of a fallacy is actually much less important in philosophy and logic than being able to carry out the analysis she provided... but if you have a specific name in mind for this fallacy, than why don't you share it?

[edit: in this thread, the fallacy I mentioned that I encountered working with my old Prof. Henry Kyberg, involving an application of the law of the excluded middle in reasoning involving provability, is an example of a fairly deep failure of correct reasoning, which doesn't have a cookie-cutter fallacy name, but deserves the rank of fallacy regardless]

[Hylas]

Yeah I'd say in general it's much more useful to be able to pick apart an argument and identify fallacious steps than it is name a fallacy from memory by just looking at an argument.

And I think linford86's one was the naturalistic fallacy or Appeal to Nature. It usually takes the form:

x is natural
Therefore x is better

Of course, there is the hidden premise of "things that are natural are better" which is obviously false.

[HappyMan]

How about . . .

No rice is snow
No snow is hot
Thus, no rice is hot

No snow is rice. False conclusion.

[xcthulhu]

How about . . .

No rice is snow
No snow is hot
Thus, no rice is hot

No snow is rice. False conclusion.

The fact that "No snow is rice" is sort of accidental in philip's formulation of the fallacy. His fallacy has the form:

No A is a B
No B is a C
.*. No A is a C

For instance, the following is the same fallacy:

No horse is a centaur
No centaur has wings
.*. No horse has wings

Notice that in this case, every one of the lines is in fact true (in Greek mythology at any rate). However, the argument is still fallacious. So while it is still a bad argument, you can't really reply "No centaur is a horse, false conclusion".

[HappyMan]

The fact that "No snow is rice" is sort of accidental in philip's formulation of the fallacy. His fallacy has the form:

No A is a B
No B is a C
.*. No A is a C

For instance, the following is the same fallacy:

No horse is a centaur
No centaur has wings
.*. No horse has wings

Notice that in this case, every one of the lines is in fact true (in Greek mythology at any rate). However, the argument is still fallacious. So while it is still a bad argument, you can't really reply "No centaur is a horse, false conclusion."

Illicit Contraposition.

no rice is snow
no snow is hot

.*. no not snow is not rice, hot is hot.

[xcthulhu]

I suppose it's abusing this thread to present crazy mathematical logic paradoxes as fallacies, but I liked this one and I thought it would make a crazy challenge to diagnose what is going wrong here exactly.

This came up in my thread on Löb's Theorem
http://philosophychatforum.com/viewtopi ... 92#p145892

As I say there:

The mathematician Leon Henkin lampooned Löb's proof to give the following "proof" that Santa Clause exists:

Let Sam be the sentence "If Sam is true, then Santa Clause exists". Assume that Sam is true then "if Sam is true, Santa Clause exists" is true; thus if Sam is true, Santa Clause exists; so Santa Clause exists exists by modus ponens. Thus we have shown that Santa Clause exists on the assumption that Sam is true and have therefore shown outright that if Sam is true, Santa Clause exists. But then "If Sam is true, Santa Clause exists" is true, ie. Sam is true, and by modus ponens again, Santa Clause exists.

What's wrong with Henkin's paradox? The obvious culprit is "self-reference" but if you look at Löb's Theorem or Gödel's theorems they employ self reference in the form of the diagonal lemma, and a lot of mathematicians and logicians believe these theorems so a little self reference should be okay...

[Ondupe]

Self reference is clearly the culprit here, after all ask yourself what the content of Sam is, If Sam is false then the "then Sana Clause exists" part of the sentence is irrelevant, hence if false Sam has no content, plausibly it is not a valid sentence for this reason.

If Sam is true then Sam's truth conditions depend on whether Santa Clause exists, it is false if Santa Clause doens't exist and true if he does, therefore if True then the content of Sam is simply the sentence "Santa Clause exists".

[xcthulhu]

Self reference is clearly the culprit here, after all ask yourself what the content of Sam is, If Sam is false then the "then Sana Clause exists" part of the sentence is irrelevant, hence if false Sam has no content, plausibly it is not a valid sentence for this reason.

Why is it then that Löb's theorem and Gödel's theorems have content?

[Ondupe]

Hehe, i'll have to read through that other thread and read up on Godel's theorem before answering that question so don't expect a response for a while, i'll message you if I end up forming a response as this particular thread will have moved on by then :-)

[notjustanyguy]

'ignorantiam, argumentum ad.........what has not been disproved is true

[geekshock]

The question implies that there are a finite ammount of bad habits. The argument cannot be supported without this prior conclusion being proven..

petitio principii...in part but not totaly..this logic breaks on several levels...

[Cartesian Fantasy]

i know its not my turn but i figured id throw this one out there anyways. its one of my favorites but my delivery may be lame :P

person A) "if you let one man take up arms they all will follow"

Person B) "that's a slippery slope fallacy, it can't be true"

*just noticed last post was forever ago....dohh

[BadgerJelly]

This is a fallacy.

[whomever]

person A) "if you let one man take up arms they all will follow"

Person B) "that's a slippery slope fallacy, it can't be true"

Argument from fallacy
http://en.wikipedia.org/wiki/Argument_from_fallacy

My turn!

Assume true that "If there was an intelligent designer, then organisms were designed."
It follows that there was an intelligent designer if organisms were designed.

[Venus]

Jesus was either a liar, a lunatic, or Lord.
Jesus was neither a liar nor a lunatic.
Therefore, Jesus is Lord.

I fail to see the logical fallacy here.

(A = X or A = Y or A = Z) = TRUE
(A != X and A != Y) = TRUE

Then if follows that A=Z must be TRUE

Clearly the premise is incorrect but that is not a logical fallacy.

[ForScience33]

Handy Guide of popular fallacies poster
Original Source and extra poster sizes https://yourlogicalfallacyis.com/poster

[TheVat]

Thanks, forsci. The Texas sharpshooter has long been a favorite of gullible journalists.

[mitchellmckain]

Back to the logical fallacy game.

Assume true that "If there was an intelligent designer, then organisms were designed."
It follows that there was an intelligent designer if organisms were designed.

Affirming the consequence.

My turn. Here is one I see quite frequently.

Alex: "There is no objective evidence for what you are claiming."

Brian: "That is an ad-hominem, so you are not an honest discussion participant and therefore your arguments are not worth listening to."

[mitchellmckain]

Actually you can probably find at least three different fallacies that would be applicable, one being a more specific type of another.

[mitchellmckain]

Ok, so one of the mentioned three applicable fallacies has already been done done above: argument from fallacy. So the leaves the other two and I have come up with another possibility which may be an even better fit.