Talk:Formal fallacy

This page is automatically archived by Archiver

Technically

Technically the second 'failed syllogism' is not absolutely incorrect (sex changes and 'non-standard XX/XY). 82.44.143.26 (talk) 18:00, 26 September 2016 (UTC)

Could you show what you mean using symbolic logic? Reverend Black Percy (talk) 18:10, 26 September 2016 (UTC)

Some people are various types of intersex and trans 82.44.143.26 (talk) 16:17, 27 September 2016 (UTC)

Well, that's true, but the syllogism just uses men and women as an example to show a formal fallacy. You are thinking of an informal fallacy. The example in the article could just as well be rendered with variables instead:

• P1. Some P are Q
• P2. All Q are R
• C1. Therefore, some P are R

We could also render it using terms completely different from men, women or gender. Say, for example:

• P1. Some walruses are hot dog vendors
• P2. All hot dog vendors are sensitive artists
• C1. Therefore, some walruses are sensitive artists.

These all convey the exact same point as far as formal fallacies are concerned. Reverend Black Percy (talk) 17:13, 27 September 2016 (UTC)

In fact, the article itself clearly states "...given the syllogism of A -> B, B -> C, A therefore C, it doesn't matter what A, B and C actually are. If the statement is incorrect because of the content of A, B or C, it would be an informal fallacy, not a formal fallacy because the logic works out." Reverend Black Percy (talk) 17:18, 27 September 2016 (UTC)

I am sorry, @Reverend Black Percy, could you please elaborate on why your examples with variables and "completely different terms" are formal fallacies? Example with variables seemed as logically valid. For the case when my brain is completely broken (who knows?), I've googled it and found exactly the same example from what seems to me as an academic source (sorry for the bulky link instead of using pictures hosting): https://books.google.com/books?id=hcyTo5genQ4C&pg=PA586&lpg=PA586&dq=some+p+are+q+all+q+are+r+therefore+some+p+are+R&source=bl&ots=fX9XwSy5ib&sig=hsoaoLw8HLz4zsuPrVlY8gKFOGg&hl=ru&sa=X&ved=2ahUKEwjFvJPY-cbcAhWjQZoKHRYzDMkQ6AEwBXoECAQQAQ#v=onepage&q=some%20p%20are%20q%20all%20q%20are%20r%20therefore%20some%20p%20are%20R&f=false

In that source, on p. 586 under the title "Quantified Syllogistic Reasoning", it is written: "An example of the logically valid syllogistic argument is

• Some Londoners (P) are soldiers (Q)
• All soldiers (Q) are well fed (R)
• Therefore Some Londoners (P) are well fed (R)

So why is it a formal fallacy? Also note that examples from the article have different quantifier premise in P2: Some instead of All Is it that you just made a typo or something was misunderstood by me? Thank you. ^{— Unsigned, by: 162.210.198.130 / talk}

A fallacy

I removed the quote by Donald Trump that stated "France is no longer France" is fallacious.

The reason I have in the edit:

The provided example equivocates "no longer" with "not". "France is no longer France" is different from "France is not France" — the second is fallacious, while to the first classical logic does not apply ("no longer" implies a change in time). ^{— Unsigned, by: 194.181.243.75 / talk / contribs}

I put it back in. If you can find a funnier opening quote, I'm all for it. But please note that the article is "formal fallacy", not "informal fallacy". As such, the quote is meant to be read as "P is no longer P". And that is formally fallacious. I can demonstrate this by asking the follow-up question "I'm sorry, what is no longer P?". If the answer is P, then it's busted. Another way of putting it is:

• P1: Something is no longer P.
• P2. That which is no longer P, is P.
• C1. It's P that is no longer P.

This is a broken referent. Note that saying P has become false is different. This is instead arguing that some as-of-yet-unnamed variable isn't P anymore. Which variable isn't P anymore? It's P that isn't! Which is fallacious. It's basically like a variant of Russel's paradox (i.e. 'P is no longer a member of itself').

TL;DR: The referent references itself as the referent which the original referent no longer references. Wait, which referent? There you go. Reverend Black Percy (talk) 13:03, 27 July 2017 (UTC)

Incorrect, you are assuming, in a manner that totally ignores the context of the statement, that both uses of the same word must have the same meaning, otherwise the statement is "Q is no longer P." The meaning of the statement is "the place called France is no longer the culture called (or more accurately "that we think of as") France." You do not want to introduce an article called "formal fallacy" with a statement taken out of context, arguing for a claim it was not making. Don't introduce a page on logic with blatantly faulty reasoning. Nog Bogmire (talk) 14:53, 27 July 2017 (UTC)

I agree with Nog, it's clear what Trump meant. Grice's razor and all that. Christopher (talk) 15:01, 27 July 2017 (UTC)

@Nog You reference "context", oblivious to the fact that the very concept of "context" belongs to informal logic. Formal logic is not 'contextual', ever — and demands that it somehow be are not even wrong. Furthermore, I can't help but notice your reliance upon alternating between different specific meanings of the same word, "France" (the place vs. the culture). This, by the way, is also informal (and thus doubly invalid here). You claim that Trump's statement is better formalized as "Q is no longer P". I must provide the obvious objection to this formalization; the fact that Q never was P. Q, you see, was (and is) Q. That's why it's called Q; it is also a result of being called Q. (This would be circular, were it not axiomatic. Yay!) It's P that is (and was) P. Likewise, being P is a direct result of being P — not of being some other letter. This is deductively true, for the record. The statement "Q is no longer P" makes no formal sense. Q never was P. It could've been that things were Q, and now things are P instead (e.g. if Q then P). But that's completely different from claiming that Q has become (i.e. warped into) P. Q never stops being Q. What Q "represents" is a question of informal logic and doesn't concern us here (see the above topic for an explanation of how formal =/= informal). As such, as simple snark (which I could defend solely on the grounds of it being funny rather than formally correct), the Trump quote works wonders as a light-hearted chuckle on behalf of formal logic. This, aside from the fact that negation introduction is a literal formal fallacy which the Trump quote illustrates nicely (i.e. in establishing France he revokes France).

@Christopher See my reply to Nog. As much as I am an absolute newb at it; has anyone here actually studied formal logic but me? Reverend Black Percy (talk) 15:27, 27 July 2017 (UTC)

That really doesn't matter. Context, when talking about an existing statement, determines what terms of formal logic are abstracted from it, ie, if both words actually have the same meaning or not, and therefore if the statement is "P is no longer P" or "P is no longer Q." You can't just skip past how language works to get your example, anyone who looks at the page is going to immediately say "but that's not what he was saying." That's not a good example. And cheap "let's all laugh at Bush saying silly things" redux is not a valid reason for presenting a bad example.

How the fuck can you know Q was never P with no context? What if Q is "gasoline" and P is "crude oil?" According to you "that compacted metal cube is no longer a car" isn't a valid statement. Please think about these things. Nog Bogmire (talk) 15:30, 27 July 2017 (UTC)

"Skip past how language works" Linguistics are obviously not a feature of formal logic. That being said however, the quote is funny. We allow 'funny' for its own sake on here, for the record.

"Also, according to you "that compacted metal cube is no longer a car" isn't a valid statement."

I don't recall ever having said that. Nor would I say that, because it's nonsense. You even use the word "valid" to imply logical validity without separating between informal and formal validity. As such, it's not even possible for me to tell what your precise accusation is, though I assure you (in all propositional outcomes) that it is an incorrect accusation. Note also that Trump doesn't say "France is no longer Spain" (i.e. "that compacted metal cube is no longer a car"). He says "France is no longer France" (i.e. "that compacted metal cube is no longer that compacted metal cube"). At this point, could the fallacy be more obvious?

Please don't get angry. What I will say, since you take the liberty to e-yell at me, is that it's quite plain you do not understand the difference between formal and informal logic. If you did, you wouldn't make the exact complaint that you are making, which is one of informal meaning (e.g. "gasoline", "crude oil" as opposed to symbolic logic (e.g. P ∨ ¬P). I advise you to study up on the meaning of formal and informal logic before continuing this discussion, as it will prevent you from — unbeknownst to yourself — making basic errors like the one you just did. No offense, friend. Reverend Black Percy (talk) 15:48, 27 July 2017 (UTC)

No, you don't understand that you can't just assign formal logical variables to words with no regard as to what those words mean. You have a fundamental premise that "the word 'France' in this statement has the same meaning in both instances, therefore it can be assigned the value P in both instances." Because of this, your inference is false and your conclusion is irrelevant. You're building this argument backwards. Nog Bogmire (talk) 15:53, 27 July 2017 (UTC)

What you miss here, again, is that while informal logic is irrelevant to formal logic, the reverse does not apply. You can have formal logic without informal logic, but you can't have informal logic without formal logic. And while the statement "France is no longer France" isn't false, that's only because it breaks apart before even reaching the truth table. France, surely, is France. Whatever France is, it has to be France, right? I mean, whatever France is or is not, it's certainly France. To say that France is no longer France is to imply that France isn't France anymore. But how could that be? France is precisely France, whatever France is. France could be something. France could be nothing. What's still known a priori is that France (of all things) certainly is France in all these scenarios. It's even France by virtue of being France. This is deductively true, a priori. There exists no situation where this is false. Reverend Black Percy (talk) 16:01, 27 July 2017 (UTC)

Just as an olive branch. I can't stand boastful winners. All the best, Reverend Black Percy (talk) 16:05, 27 July 2017 (UTC)

Again, this only applies if you assume that "France" means the same thing both times it is used. What justifies this assumption? I mean sure in formal logic you can't have definitions external to the argument itself sneaking in because it's letters, but you have to get these words into formal logic from a place where that is possible. "France" isn't an abstract P with no definition yet, it's a word that means things.

I'll try explaining it all from the other way around, see if the hat fits better that way.

Step one: There's this thing present in all systems of logic called the law of identity. It applies informally as well. As TOW puts it, "be it a universal or a particular", it applies across the board. Any given thing is itself. (Just to be clear, the supposed absence of the law of identity literally cannot be formalized; i.e. results in the very definition of the word 'illogical'). That's step one.

Step two: "France is France" is tautological. And while people often joke about tautologies, a true tautology also means the statement is deductively true, a priori. We know it to be correct. That's step two.

Step three: what do you suppose happens when we change the statement into "France is no longer France"? Keeping in mind that the same power granted to the surefire formulation "France is France" stems from the tautological form of that statement? Reverend Black Percy (talk) 16:21, 27 July 2017 (UTC)

To give an example: I point and say, "that car is not a car." Ah, P and P, right? What if I'm pointing to a cablecar and I mean it's not an ordinary car with wheels? Nog Bogmire (talk) 16:07, 27 July 2017 (UTC)

"That car is not a car" formalizes as "P ∨ ¬P". Same problem there. Reverend Black Percy (talk) 16:21, 27 July 2017 (UTC)

But again, this only works if you assume "France" is already an abstract term of formal logic which only has one possible definition. As I pointed out, this doesn't work, it is possible for something to be a car in one sense but not another. Nog Bogmire (talk) 16:24, 27 July 2017 (UTC)

Switching between contextual definitions of the word "France" (in the way you propose, country v. culture) would look like this when formalized. I.e., doing so is a fallacy. Note also that the discussion doesn't involve me denying that France is a word with multiple meanings in totality. That would be ridiculous. All I'm saying is, there is no case in which France is no longer France. France is always France. It always was, and it always will be. I know this for the simple reason that France is France. It's the negation done by Trump that's retarded. As surely as the tautology is deductively true, it's deductively false that France is no longer France. In fact, it's only France that is France, and nothing but France is (or could ever be) France. Reverend Black Percy (talk) 16:26, 27 July 2017 (UTC)

It could be, except it's a flat statement, not a logical argument, so it can't commit a logical fallacy. And no, you're still trying to make that same point. Language doesn't work that way, I can have 400 horses under the hood of my car and no horses under the hood of my car at the same time. Nog Bogmire (talk) 16:32, 27 July 2017 (UTC)

...what you can't have, though, is something that isn't the same as itself. Reverend Black Percy (talk) 16:34, 27 July 2017 (UTC)

But can say thing B is no longer true of thing A even though the same word is used to describe both things. Nog Bogmire (talk) 16:36, 27 July 2017 (UTC)

Certainly, but you discuss truth and falsehood. My point is that whatever happens, B is still B, and A is still A. There is no scenario in which B is no longer B or A is no longer A. They are themselves, in all instances. There is no concievable way around this. Reverend Black Percy (talk) 16:38, 27 July 2017 (UTC)

The problem is that your argument here is that B is A. Nog Bogmire (talk) 16:40, 27 July 2017 (UTC)

I'm not making an argument. Trump is making the argument that P is not P. But P is P, just as a rose is a rose is a rose. A thing is itself, by necessity. Reverend Black Percy (talk) 16:42, 27 July 2017 (UTC)

No, Trump is arguing definition of word A no longer applies to an entity B that is described with the same word. Nog Bogmire (talk) 16:43, 27 July 2017 (UTC)

...and that, kids, is where we get the fallacy! *puffs pipe* (PS: Not in Trump's argument, but in yours). Reverend Black Percy (talk) 16:45, 27 July 2017 (UTC)

That's not how that fallacy works. Nog Bogmire (talk) 16:46, 27 July 2017 (UTC)

...Oh, so your argument doesn't depend on alternating the reference of the same referent? Reverend Black Percy (talk) 16:47, 27 July 2017 (UTC)

No, my argument doesn't, the original statement does. You don't use logic to decide what people said, you nitwit. Nog Bogmire (talk) 16:49, 27 July 2017 (UTC)

Calling people nitwits isn't logical! I win! Reverend Black Percy (talk) 16:52, 27 July 2017 (UTC)

Actually you just made it a logical inference :P Nog Bogmire (talk) 16:53, 27 July 2017 (UTC)

Let's just explain this a little better:

"France is no longer France."

Your reading:

"France" (P) is no longer "France" (P)

Fair enough, that's an example.

The intent though, is

"France, the country" (P) is no longer "France, the place full of white Christians who eat snails or something" (Q) (meaning Q is an attribute which P may or may not have, not a distinct entity)

This isn't a statement about two abstract variables. Now you're fine to argue it's equivocation (though it really can't be because it's only P is not Q rather than X is P, Q is Z, therefore X is Z as the fallacy would require: the point of equivocation is it treats the two terms as the same or hides that they're not, it can't blatantly contrast them) but that's what he was saying, not the other thing. Nog Bogmire (talk) 17:02, 27 July 2017 (UTC)

Again, the relevant error occurs before the informal ruleset takes the field. The fallacy is formal — in that the argument points to a thing and states that the thing that it's pointing at (France) isn't the same thing that it's pointing at (France). It's like if I were to point to you and say "this person isn't the same as the person I'm pointing at". It's not a question of true or false; it's plain incoherent. Thus, the proper formalization of Trump's statement is (P ∨ ¬P). Note that in your initial interpretation given above (which commendably uses only his exact words), you yourself seem to find the meaning to be P ∨ ¬P. So far so good.

But you then provide an "alternate version" of his quote, which inserts tons of specific words Trump never actually used in his exact quote, and based on said additions, you conclude (quite correctly) that your "version" seems to mean something else than Trump's actual verbatim quote (i.e. the one you yourself agreed to mean "P ∨ ¬P") — this, by virtue of your novel inclusion of tons of words that simply were not explicitly said by Trump in the relevant quote. I mean, there has to be a functional difference between the words Trump actually said and the words he didn't actually say. Reverend Black Percy (talk) 17:21, 27 July 2017 (UTC)

The fallacy is only formal if you make a specific assumption, ie that the same word used twice must mean the same thing. The "verbatim quote" has a context, which, as Christopher already pointed out, makes the intended meaning (which I gave) extremely obvious. As I noted, you are ignoring that the second France is clearly intended to be an attribute of the first that it can either have or not have. Principle of charity and all. Nog Bogmire (talk) 17:28, 27 July 2017 (UTC)

You use the word "meaning" as if formal logic is not fundamentally the study of meaning. Also, the principle of charity — beloved by all — belongs to informal logic, for the record. Here's another deductively true statement: you'd already be aware of this fact if only you were already aware of this fact. Reverend Black Percy (talk) 17:34, 27 July 2017 (UTC)

Then maybe you shouldn't start your study with a blatant strawman? Nog Bogmire (talk) 17:32, 27 July 2017 (UTC)

What, in asking that Trumps own words be the exact words we attribute to Trump? Reverend Black Percy (talk) 17:34, 27 July 2017 (UTC)

Yes, if you ignore the intention of those words and just assume he would point at a thing and say "hey, this isn't this!" Nog Bogmire (talk) 17:35, 27 July 2017 (UTC)

No reasonable person assumes that (though that's still far fewer people than you'd think). Certainly noone would assume Rationalwiki assumes that. As such, following another convention of informal bickering, any reasonable person would assume we're deliberately changing the meaning of his words to a literal one as a humorous way of providing demonstrational material. Which is what we're doing. I even offered to put "(if taken literally)" in, but Chris reverted it. ~ ♥ 17:44, 27 July 2017 (UTC)

Yeah, but a blatant strawman isn't a good example for a logic page when I'm sure there's plenty of examples of people using real formal fallacies out there that we could use, and I personally find the "haha, Trump is dumb" jokes almost as played out as saying he's orange. Nog Bogmire (talk) 17:48, 27 July 2017 (UTC)

[EC]I reverted because during a dispute like this the article in question probably shouldn't be edited (except for typo correction and that sort of thing). Christopher (talk) 17:49, 27 July 2017 (UTC)

For the record: I know think the quote should be kept, it's not what Trump meant but that's sort of obvious. Christopher (talk) 18:28, 27 July 2017 (UTC)

We have consensus! Reverend Black Percy (talk) 18:33, 27 July 2017 (UTC)

Getting the basics in order

Hope this helps! Reverend Black Percy (talk) 17:31, 27 July 2017 (UTC)

Another quote worth thinking about

“”stop trying to abuse the rules for trolling you useless bag of cocks

—Nog Bogmire

...he said, as he blanked a helpful talkpage post for the 2nd time. And with that, I'm out. Reverend Black Percy (talk) 17:43, 27 July 2017 (UTC)

Yes very helpful and not at all trolling to link me to a video about something I already understand. Nog Bogmire (talk) 17:49, 27 July 2017 (UTC)

...So that's a really nice apology. :/ Reverend Black Percy (talk) 17:55, 27 July 2017 (UTC)

Sorry, did you do something that would result in my wanting to apologise to you that I wasn't aware of? Nog Bogmire (talk) 17:57, 27 July 2017 (UTC)

Calling him a useless bag of cocks? Christopher (talk) 17:59, 27 July 2017 (UTC)

No, clearly I only called him P, because that's how language works now. Nog Bogmire (talk) 18:00, 27 July 2017 (UTC)

No, you removed talk page posts and called one of the nicest people on the site (from my experience anyway) a useless bag of cocks and a troll, and now you're trying to dodge the subject by bringing up the original dispute again. Christopher (talk) 18:07, 27 July 2017 (UTC)

What do you want? I'm not going to apologise to someone who's just spent five hours talking down to me. Nog Bogmire (talk) 18:10, 27 July 2017 (UTC)

*fire blankets Nog with sane people* @LeftyGreenMario @Bongolian @JorisEnter @RoninMacbeth Reverend Black Percy (talk) 18:12, 27 July 2017 (UTC)

Case in point. Nog Bogmire (talk) 18:12, 27 July 2017 (UTC)

See the main article on this topic: Victim blaming Reverend Black Percy (talk) 18:14, 27 July 2017 (UTC)

You're not helping. Nog Bogmire (talk) 18:17, 27 July 2017 (UTC)

I don't even know what that's supposed to mean... Let me tell you a story instead. When I was a kid, I was taught to alert people when something happened that sucked. I've always found it to be good advice, though perhaps I've been blessed to have such damn fine people around to answer my call and offer me naught but their presence and witness. No matter who had done what to whom, calling good folks' attention to it all's like a magic bullet for de-escalating things. Reverend Black Percy (talk) 18:31, 27 July 2017 (UTC)

...OK, what the hell is going on here?! RoninMacbeth (talk) 18:30, 27 July 2017 (UTC)

De-escalation, I hope. And maybe some conscience searching. Reverend Black Percy (talk) 18:47, 27 July 2017 (UTC)

Alright, that's good. Message me if it flares up again. RoninMacbeth (talk) 18:49, 27 July 2017 (UTC)

OK, good to hear that things are de-escalating. Good advise from RBP regarding alerting people. Give people the benefit of the doubt when possible. Bongolian (talk) 02:09, 28 July 2017 (UTC)

Request for time-out

* dons Mod Hat * 

Everyone please sit back and avoid touching this page or this talkpage for a day. Come back tomorrow cool-headed. Herr FüzzyCätPötätö (talk/stalk) 19:00, 27 July 2017 (UTC)