CRITICAL THINKING - Fallacies: Formal and Informal Fallacies

In this Wireless Philosophy video, Paul Henne (Duke University) describes the distinction between formal and informal fallacies. This distinction is useful for understanding the fallacies in Wi-Phi's Critical Thinking section.
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[@user-dm6tr3ht4z]

i have learned more in the past 7 minutes and 4 seconds of this video than i have in class for the past 5 weeks. thank you !!!!!!!!!!!!!!!!!!!

[@sinemkadrioglu8194]

Thats a thinking fallacy.Probably this video made somethings clear in your mind then you concluded that you learned a lot more from this video. (Video is still awesome )

[@sinemkadrioglu8194]

@Ben F thank you for your reply

[@sinemkadrioglu8194]

@Ben F you are totally right

[@noahm44]

You have not been listening in class lol.

[@baruchspinoza5146]

This is great, I just wish that Henne didn't suggest that all philosophers publish articles in philosophy.

[@christinacamp5678]

It was articulated correctly for instruction of this form.

[@braedondavies9592]

Formal comes from form. I feel enlighted...and also kind of embarrassed that I didn't realize this before.

[@REDRAGON12345]

Coming from a philosophy graduate student, you did a great job! Very clear and articulate.

[@folumb]

These videos have been gold in this election cycle

[@shawniscoolerthanyou]

They'll be good in every election cycle.

[@micahmicah402]

@@shawniscoolerthanyou I am from the future and I can confirm

[@DigitalAndInnovation]

This is like the fallacy 202 class. I love how you got into relatable examples and then went from there!

[@sizzlingsausage8413]

Great videos! At 2:42 you say "A formal fallacy is exactly what it sounds like, a defect in the form of an argument" I always thought it had something to do with etiquette (formal as opposed to casual), so not really "exactly what it sounds like". Maybe a term like "structural fallacy" would be clearer (though clearly non-standard).

[@thetruthis24]

Form & content

[@sambou6286]

form from formalism (formation) not formality. Structure has a meaning of something bding organizational, so, doesn't' really work here.

[@McGee870]

I don't speak Spanish but I think it is amazing that you included subtitles in Spanish! Also, great video. I appreciated the content!

[@McGee870]

Also, is it that informal is linguistic and formal is non-linguistic?

[@tobediscontinued1795]

I'm sorry but 1:48 is not a valid argument. Your premise is off by asserting that if one is a Philosopher that they automatically publish. This isn't necessarily true. So this premise is off which threw off the relevance of the second assertion, even though it was true.

[@petresilegov2581]

Before watching the video I will try to find the fallacies present in the arguments in the beginning. Argument 1: Black and White fallacy (there is more than one reason why people don’t eat peanut butter) Argument 2: Equivocation fallacy

[@cheungchau3982]

I am surprised that no one points out that “a feather is light” doesn’t imply “all feather is light”. Yes, I am not a native speaker so I was thinking about a light colored feather. So “a feather is light” but “another feather can be dark”. Therefore, I spotted a different fallacy - “faulty generalization”

[@GovernerOfBurningHam]

last time I was this early, I was eating breakfast. therefore, last time I was eating breakfast, I was early

[@daffmaul9813]

It seems like affirming the consequent is done by using inductive logic. If so, are there any examples of inductive arguments that do not affirm the consequent?

[@tranhtrieu24]

This gentleman here made this so easy to understand vs my teacher

[@ExMachina70]

01:46 This statement is incorrect. First, you said "then she" instead of "then they", but the worst mistake made is that all philosophers publish articles in philosophy. By that logic, Socrates was not a philosopher.

[@mohaumakhoba7354]

Ah, screw it, I'll just fail my assignment, it's fine.

[@EriconatorV2]

On the peanut butter one, would changing the argument to "if someone is allergic to peanuts, then she shouldn't eat peanut butter" not be considered fallacious?

[@mochrifani5172]

Thank you

[@WirelessPhilosophy]

You're welcome

[@julietted2865]

Hi! So it's sort of referred to in some comments but not explicitely: Is anyone clear on why Cum Hoc and Post Hoc are considered Informal fallacies rather than formal? Deductive fallacies have me stumped because they are neither about the truth or instrinsic relevance of either premise (informal), nor the structure of the argument in itself (formal), but about a degree of over-assumed relevance… Anyone?

[@FriedEgg101]

Very nicely explained, thank you.

[@robertotandoi4224]

P1) If I affirm the consequent, then I produce a fallacy P2) I affirm the consequent C) Therefore I produce a fallacy This seems paradoxical to me. Any suggestions ?

[@theesotericeccentric589]

unsure as to whether this is still being monitored but wouldn't affirming the consequent be circular logic? i find this topic is so lacking a consensus as i notice the slippery slope fallacy and hasty generalisation to also be of the same rough definition?

[@yftachman]

It's about context. A slippery slope talks about consequences. If we do A, Z will eventually happen therefore we can't let A happen. A hasty generalisation talks about asserting things, i went to New York and ate only at pizza places, therefore New York only has pizza places. You could make categories for the fallacies and some would be in the same category, but they are different :)

[@l8egg_]

very clear and interesting video! great stuff, keep it up

[@stephenblackwell7351]

what kind of fallacy is feminism?

[@murr395]

What do you mean?

[@Strr27]

is it too late now to say sorry?

[@madvolleyball95]

Well, feminism is a broad movement which encompasses many different beliefs and not a single argument...it takes some fallacies to dismiss an entire group like that(for exanple composition, division, hasty generalization fallacies) Overall, not the right approach I would say. I'm sure you will find many philosophers sympathetic to feminism as well. That being said, of course nothing is off limits for criticism :)

[@anarchyseeds4406]

Ad Hominem + Overgeneralization

[@rlrnilecroc]

Loaded question

[@grambo4436]

Can that be applied for Straw-man Fallacy too?

[@tommytucker5464]

+Borat Sagdiyev really I would've thought top fallacies for online argument would be ad hominem fallacy

[@ChrisMerola]

this video is so slick and buttery smooth, god damn

[@mikewagenblast8504]

Inquiry - What fallacies are involved in the Edward Snowden situation? Thank you.

[@rinayuliana8586]

Thank you for your information,,

[@stephenanastasi748]

Socrates was a philosopher. If your argument regarding Tamar Gendler were true, then Socrates, who never wrote anything, was not a philosopher. Good luck with that. I don't mean to be harsh... it just comes naturally. Maybe an edit?

[@thandongcobo4711]

So can informal fallacies be valid

[@meganmariebott4125]

This was very helpful.

[@sgtboots6847]

Its been 3 years. Have you graduated? Are you perusing a PhD?

[@GingAzaravlog]

Hello thank you for sharing this

[@thepubliusproject]

I'm not sure I've ever seen logical fallacies laid out in such a convoluted and unclear way when the intent was to speak to people with no formal training. I think that Henne is a good Philosophy student. I'm not convinced he's a good Philosophy _teacher_ however.

[@dianabarrientos6751]

Great video, editing and graphic use.

[@shankaranpillai9664]

1. Fallacy of relevance. 2. Fallacy of defective induction. 3. Fallacy of presumption. 4. Fallacy of ambiguity.

[@kgbyrd8204]

What fallacy is referring to everyone as "she"?

[@weekdays206]

Thank you!

[@vincenzhog8347]

well explained

[@marcusuitoh9374]

I get your point with the second example. But when it is stated the arguement is not necessarily invaild. It can be understood in more than one way, two or which are correct. Case #1 P1: A feather is light (color). P2: What is light(color) cannot be dark. C: Therfore a feather is light(color). Case #2 P1: A feather is light (weight). P2: What is light(weight) cannot be dark. C: Therfore a feather is light(weight). Problems arise in the cases where the meaning is switched. You make the assumtion that people choose to understand the contents in the same way as you. Though it is a great example of the dangers of not clarifying ambiguity when putting forth an arguement.

[@AlanKey86]

Good point, well made. I, for one, took the "feather is light" premise to mean lightweight. Perhaps a less ambiguous example could've been: P1: A feather is soft P2: What is soft cannot be loud C: A feather cannot be loud

[@rumplstiltztinkerstein]

Marcus, your conclusion on both arguments is the first sentence. x is y y is not z (then) x is y. You should run into politics

[@niclasbengtsson6574]

But you don't have to publish articles in philosophy to be a philosopher...

[@anarchyseeds4406]

So what you are saying is that the argument is not sound. Still valid.

[@niclasbengtsson6574]

Anarchy Seeds Yes, that's exactly what i'm saying...

[@reptilesgamers00]

Somebody help me find the name of this fallacy. Common argument occurs in the house. The dishes need to be done, you walk into the kitchen finding the dishwasher partially filled with dishes. You check a bowl for signs the dishes are clean. You find dried oat meal in the bowl. You concluded the dishes in the dishwasher are dirty after finding three+ dirty dishes. You start cleaning the dishes, scrapping off the food, placing the dishes in the washer. Girlfriend comes into the kitchen telling you the dishes in the dish washer are clean. She states she washed them this morning. You show her the dirty bowel and a few more dirty dishes that were in the washer. She gets offended by your assumption she did the dishes incorrectly. She replies, "Somebody probably put the dirty dishes into the dish washer by accident after I washed the dishes. i'm not stupid, I know how to wash the dishes." (You know what she is saying isn't true because NOBODY in this house puts dishes into the washer. They stick them in the sink and they sit there until someone cleans them. The last person who did dishes is the only one putting dishes into the washer.) That's the fallacy. One finds a situation that could be true, you must assume it is true, or you being purposely unreasonable. If we can't tell definitely what happen, one can state something convenient in relationship to the subject, you must find this "agreeable" or appear unreasonable. I've experienced this many times. A convenient explanation isn't equivalent to the truth. Just because it could be true, (it's plausible), we can pass it as truth? The closest name I've found for this fallacy is "wishful thinking" and "reverse kafka trapping". Anything else? FYI: I just said "ok:" and did the dishes after her response. Better then make her mad, lol

[@Fayarin]

reptilesgamers00 Moving the goalposts.

[@bp56789]

Maybe 1. you're wrong about nobody putting dishes in the dishwasher, or 2. she's wrong to claim she knows how to wash the dishes, or 3. she's wrong in thinking that she'll never make a mistake with the dishes because she knows how to wash them. (1) and (2) are false premises. (3) is a conclusion ("I know how to wash them, therefore I never fuck up") that does not follow, which is called a "Non sequitur". I'm guessing it's (3).

[@LearnwithMsKath]

Thank you Sir your lectures helps me a lot.

[@truthseeker7815]

It took me many seconds to realise of the explanation of the second example because I'm Spanish and the different meanings of "light" in English language are different to the different meanings of "light" in Spanish language xd

[@alexanderquilty5705]

I wish you had all the fallacies :(

[@kenichiotaku3693]

That would include all arguments for God that were ever put forward and that's a lot. x'D

[@ianonymous3803]

Garbage, if the premise in incorrect (e.g. not all philosophers publish anything) then the conclusion is also garbage.

[@DeAnn909]

Very helpful..;)

[@gkiltz0]

Example I use: All of Elvis is dead, but not all dead people are Elvis

[@pinkfurryhat]

politicians need to watch this and other videos on fallacies, along with anybody with a political opinion. left and right.

[@Paygelove]

Fallacy = all the stars are spheres therefore the earth must be a sphere

[@thenarrowpath6661]

Im proud that nobody has refuted this comment yet, whether it is actually true or not.

[@user-ie3ze6tc3u]

NICE

[@BramaKnox]

Can you repeat that? RIP

[@rereabdieldzaka1363]

[@anarchyseeds4406]

The word "therefore" is not part of the conclusion, it introduces the conclusion.

[@dirrogetachew3432]

nice

[@fluentpiffle]

The world is run by conmen.. "Mathematics has the completely false reputation of yielding infallible conclusions. Its infallibility is nothing but identity. Two times two is not four, but it is just two times two, and that is what we call four for short. But four is nothing new at all. And thus it goes on and on in its conclusions, except that in the higher formulas the identity fades out of sight." (Johann Wolfgang Von Goethe)

[@Zeracool]

Many things that you wrote as true are false, like "If someone is allergic to peanuts, then she doesn't eat peanut butter" Lots of allergic people consume products they are allergic to, actually.

[@marshallpoe4]

A valid argument doesn't necessarily assume its premises are true.

[@mudassarmuhammad5329]

Man use some real life examples n tricky ones... For the love of GOD u r a Duke University student..

[@Ed-tc2pg]

👍

[@e27434]

marquardt anyone

[@peterjchaze]

So then just call it a fucking content fallacy or contextual fallacy and a formal fallacy. Why make it harder to remember the difference?

[@purplealice]

Millionare Bill Richbucks smokes Lucky Strike cigarettes. If smoke Lucky Strikes you can become a millionaire!

[@armorofgod777]

where my new wgu homies at

[@kentam5361]

Donald Trump is the fallacy king.

[@truthseeker1871]

I've been led to believe that something called informal logic/informal reasoning has been around for something close to 70 years. I don't understand why it hasn't been cast out as a fraudulent movement. Any thoughts on that? My thought is that if it promotes deception (and I think it does) then it ought to be eradicated as a subject worthy of honest peoples inquiry.

[@brd8764]

Informality lacks content. It is mediocrity.

[@lyndsayastor9668]

wow i dont like this portion of phil

[@millerk20]

X and Y? P and Q...get with the program.

[@JimmyCurry]

Mixed emotions. I love Trumps honesty, but that honesty is also some sexism, racism, blind nationalism, and belittling of handicapped, etc. If he could be more compassionate, scholarly, he would be a much better leader. Hopefully, as President he doesn't just surround himself with bankers, war mongers, racists, etc, and instead reaches outside his comfort zone for people that have different cultures, political affiliations, from different socio-economic groups and religions. Let's see. One thing he is, a great entertainer.

[@humanitiesteacherp1457]

How'd that work out? Not being a jerk - did he live up to your hopes or fail miserably?

[@garybuttherissilent5896]

Racism is a much smaller problem people like to believe.