CRITICAL THINKING - Fundamentals: Validity [HD]
Vložit
- čas přidán 30. 10. 2014
- In this Wireless Philosophy video, Paul Henne (Duke University) discusses the philosophical concept of validity. After reviewing the structure of an argument, he defines validity: an argument is valid if and only if its premises guarantee the conclusion. He reviews a few examples of validity and invalidity, and he leaves you with one example to figure out on your own.
Help us caption & translate this video!
amara.org/v/GcHM/
![PHILOSOPHY - Rational Choice Theory: Tragedy of the Commons [HD]](http://i.ytimg.com/vi/lj_gLquca7Q/mqdefault.jpg)
![PHILOSOPHY - Rational Choice Theory: Tragedy of the Commons [HD]](/img/tr.png)
![CRITICAL THINKING - Fundamentals: Soundness [HD]](http://i.ytimg.com/vi/3P0fUHUaZcs/mqdefault.jpg)
![CRITICAL THINKING - Fundamentals: Bayes' Theorem [HD]](/img/n.gif)
shout out to all my fellow university students trying to get by in there philosophy course
help
i am drowning
@@alijane5116 why whats wrong?
Their
@@alijane5116 same
aaaaayyyy
this is so hard!!! i have to know this for class and once i start feeling like i finally understand i get hit with a question and everything i thought i knew goes out the trash.
If you want to think more abstractly about these types of problems without having to replace things with letters or choose new items that make the premises true, here's an interesting approach that thinks of the items as boxes being placed into other boxes. This works because putting things in boxes allows us to imagine items in physical positions, making their relationships to each other in space clear.
*Original*
All fruit is a chair.
Square is a chair.
Conclusion: Square is a fruit.
*Box Translation*
The fruit box is in the chair box.
The square is in the chair box.
Conclusion: Is the square in the fruit box?
Answer: No, as far as we know, we only put the square in the chair box.
Premises tell you to take an item and put it in a box. Conclusions are yes or no questions about which box an item is in.
For a comparison, look at this valid version of the argument:
*Valid version*
All fruit is a chair.
Square is a fruit.
Conclusion: Square is a chair.
*Box Translation*
The fruit box is in the chair box.
The square is in the fruit box.
Conclusion: Is the square also in the chair box?
Answer: Yes, since the square is in the fruit box and the fruit box is in the chair box, the square has to also be in the chair box.
Thank you so much!
@@user-ys4pm4hu6m i always try to help potatoes.
I don’t think I can thank you enough. Your explanation is very easy to understand!
@@imissmybed3469 i'm glad it helped! i took a logic class over a year ago, and i created this approach randomly and it saved my life. 😅 i felt it would be easier if i could look at these logic problems physically.
Wow you actually just helped the concept click for me. Very helpful approach!
Invalid. All fruit may be a chair, but vegetable may be a chair as well. Square could be vegetable.
*a
this is a great example
So if it was phrased:
All fruit is a chair
Square is a fruit
Therefore, square is a chair.
would that be valid
(sorry if it sounds stupid, just learning it now)
@Aquila Aeternus invalid.
P1 : All human is a mammal
P2 : Cow is a mammal
C : Therefore, cow is human
Example of valid argument :
P1 : All human is a mammal
P2 : Cow is a human
C : Therefore, Cow is a mammal
@@McDnyss Yes it would,i was going to write that but fortunately you did.
It becomes borderline impossible for me to understand what's going on when they throw out nonsense phrases like "all fruit is a chair"
Matt11111 we are doing this in class and I am confused as well
Guys are you in aurak course PHIL 100
It's a tricky question formulated to make you think abstractly.
Let's replace some of the words with letters. They're arguing this:
Let A = Fruit, B = Chair, C = Square
P1: All (A) Fruit is a (B) Chair
P2: (C) Square is a (B) Chair
Conclusion: Therefore (C) Square is a (A) Fruit
The premises and conclusion are obviously false, but notwithstanding, the form of the argument is that (A is a B) AND (C is a B), therefore (C is an A), which isn't valid. We can reuse the form of the argument, changing the premises to be true and test the conclusion to see if the argument holds up:
Let A = 16th-century explorers, B = Human, C = Matt11111
P1: All (A) 16th-century explorers are (B) Human
P2: (C) Matt11111 is a (B) Human
Conclusion: Therefore (C) Matt11111 is a (A) 16th-century explorer
So, you tell me - it's the same argument and all the premises are true but are you necessarily a 16th-century explorer just because you're human? The argument is invalid because the conclusion can be false even though the premises are true.
@@maple.everything Josh is out here doin the Lord's work
@@maple.everything I love you
The last argument is invalid. Truth of C1 doesn't necessarily follow from the truth of both P1 and P2 (for example if both fruit and chair were both non-overlapping subsets of chair). However changing the second premise to "A square is a fruit" would make this into a valid argument.
I was butthurt they didn’t give an answer, my thoughts were that what if all vegetables were a chair too? maybe a square could be a vegetable
@@jonanddybut it’s not certain which is why it’s invalid
Is overcomplicated for your educational level?
invalid because all fruit may be chairs, but not all chairs might be fruit.
if you say "Square is a fruit" and "Therefore, Square is a chair", that would be valid.
Kurwa! że jesteś mądry :)
no jest do chuja madry
Thanks man
Had an assignment for my ethics class and this helped so much. I was struggling for an hour until I found this video. Thank you!
Invalid. It's easier to see with term substitution where the premises are accepted to be true:
All Lamborghini Countachs are cars.
A Honda Civic is a car.
Therefore, a Honda Civic is a Lamborghini Countach.
All citrus fruits are acidic.
An orange is acidic.
Therefore, an orange is a citrus fruit.
All architects are people.
A landlord is a person.
Therefore, a landlord is an architect.
All three examples follow the same form of argument, but one example arrives at a false conclusion, one a true conclusion, and the last at a contingient conclusion. In an invalid argument, the truth of the premises does not *guarantee* the truth of the conclusion. As it so happens, inductive arguments, the mainstay of science, are invalid arguments.
"As it so happens, inductive arguments, the mainstay of science, are invalid arguments."
But in isolation, right?
Thanx bro
That's what the salesperson said and I overpaid. Wished I'da watched this video first. Doh!
Hold on. I thought the whole point of the video was saying that such arguments are valid! @4:20 he literally gives the same type of example and says that's a VALID argument! Or am I missing sth here...? Correct me if am wrong but u seem to conflate Truth with Validity...
@@yodaheabebe3756 He meant "if the premises are true (somehow), the conclusion derived from the premises MUST ENTAIL THE PREMISES/MUST BE TRUE.
In an invalid argument, IF THE PREMISES OF THE ARGUMENT ARE TRUE (In real or in imagination) AND THE CONCLUSION DERIVED FROM THE PREMISES does not entail the premises/i.e: Its truthfulness is doubted
one example:
Smurfs are blue men
Night Walkers are blue men
Therefore, smurfs are Night walkers
in a valid argument if you accept the first two statements to be true (in imagination or in reality) then the conclusion MUST BE TRUE. But in an invalid argument, the truthfulness of the conclusion with relation to its true premises is doubted
This was so clear to me, thanks for the video. I understand now.
Thankyou, I feel a lot clearer on this however I still feel like I haven't fully grasped the concept of validity in philosophy.
Sabah Zarid hey, so from what I understand. Validity hasn't got anything about the actual truth of the premises or conclusion (that has more to do with the soundness of an argument). Valid arguments are when the premises actually lead to the conclusion, and you dont have to look elsewhere to check that the premises actually lead to the conclusion. For example, with the invalid argument presented at the end, the reason it is invalid is because you would have to go "outside" the argument to check if Clair is a dog, you cannot actually infer from the argument that Clair is a dog just because she has a lot of fur, Clair could be a tiger, or a cat, or a rabbit
This invalid arguement is very different from the valid one stated in the beginning, because for the one in the beginning, if the statement "all humans are mortal" is true and the statement "iris Murdoch is a human" is true, then it leads to the conclusion that "iris Murdoch is mortal". You don't have to go outside the argument to know whether the argument has lead to the correct conclusion or not.
But you would have to do that for the invalid arguement, because it's not clear just from the premises alone that claire is a dog.
Does that help?
what the heck? he didn't give the answer at the end of the video!
+Grant King Its invalid
"Metaphysics As A Guide to Morals" by Iris Murdoch is a must read!
Im trynna getting this philosophy course so that i can enhance my arguments skills, that can be necessarily used in law school.
thank you so much for helping students like me
This makes sense intuitively, but I'm interested to know more about exactly how an argument is determined to be valid. What is the method for determining if an inference follows from the premises?
That depends on the kind of argument you're talking about. Categorical logic and propositional logic offer two means by which to determine validity. Categorical logic uses Venn diagrams, while propositional logic uses truth tables.
Great video Paul!
If we were to substitute 'the chair' for 'a chair' in P1 and P2, would this then become a valid argument?
Valid:
A is B (coffee is a bean)
B is C (bean is a food)
Therefore A is C (coffee is a food)
Invalid:
A has B (dogs have fur)
C has B (Claire has fur)
Therefore C is A (Claire is a dog)
i don't see how either of them are what they are?
you left out "all". "all" is what messes it up.
@@Wedneswere
Maybe this will help:
This is the argument without the words.
(Invalid)
All A is a B
C is a B
Therefore, C is a A.
You cannot know just from the premises alone that C is an A. You would have to go "outside" the argument to clarify is C is actually an A.
If the argument was,
All A is a B
C is a A
Therefore, C is B
That is clearly valid, the conclusion follows clearly from the premises and it's clear that even without "checking", the argument is valid.
I'll do another valid argument but with words.
Valid:
All horses are unicorns
Bob is a horse
Therefore, Bob is a unicorn
Invalid
All horses are unicorns
Bob is a unicorn
Therefore, Bob is a horse.
Cannot know from the argument alone that bob is actually a horse, because we cant know all unicorns are horses. We just know that all horses are unicorns, so from the premises alone we cannot conclude bob is a horse.
Best explanation
What about this argument:
P1: LA county requires a vaccine mandate to enter stores.
P2: Vaccine mandates are discriminatory
C: Therefore, LA county is discriminatory.
Correct me if I'm wrong and you might have to draw this out... In a Venn Diagram the large rectangle would be labeled chair. Within the large rectangle would be a circle named fruit since "all fruit is a chair". Then the X mark representing square would be on the border of the circle named fruit due to the second statement not saying explicitly if square is or isn't a fruit. So there's a possibility that square is something other than a fruit making the argument invalid.
U are right, square would be in rectangle, so therefore it could be only in circle or only between circle and square and therefore it is not 100% in circle.
I was a mathematics major and for some reason this confused the heck out of me. Not sure if it was because I have a background in logic or just the way it was explained?
Kyle Aure The second video in this playlist explains validity with more clarity and less words.
Nice video and helpful!
buenas noches sería posible incluir subtitulos en español gracias
HUGE HUGE HUGE fan of yours. PLEASE never stop doing videos. There is a type of fallacy im hearing theists accuse me of. Can you help me with it? (Or someone else familiar with logical fallacies?)
Your explanation is satisfy... do updated me in your next up coming videos.. thank you Sir. From N.E India
Quality content I need on youtube
thanks this video is so amazing
In programming we use something similar to this called inheritance. Saying all Fruit is a Chair is like saying Fruit is a child of chair. This relationship is one way, Chair could have multiple children but Fruit can only have one parent. Therefore if Square is a Chair then it could be a Fruit. If Square was defined as a Fruit then it must also be a Chair.
+Turt1eXing so it is valid right? that is what I thought. I also studied that in programming.
yes, most unmanaged languages allow it, but typically you want to avoid that because its easy to end up with what we call the dreaded diamond. Where an 'apple' inherits from 'fruit' and 'vegetable' and both 'fruit' and 'vegetable' inherit from 'plant'. apple will end up with two versions of plant (one from fruit and one form vegetable) which causes a lot of problems that may be hard to notice.
Someone tell me if this is a reasonable thing to do: The final argument can be simplified by replacing some of the words with variables?
If fruit=A and chair=B and square=C then the argument goes
p1. All A are B
p2. C is a B
c1. therefore, C is an A
That seems like an invalid argument. Is there any flaw in what I did here?
Nope, that's exactly right. The actual terms themselves don't matter.
The form of this argument is the same, and it is just as invalid.
This was much easier to understand than having to deal with the mental struggle of associating things into different categories. Thanks
Good explanation👋!
when someone asks you if it makes sense, implying that's true, and you're like...
Thank you
Are whiteboard animation videos still valid?
In the example at the end, the premise both p1 and p2 are true, but the conclusion is invalid, as square is not a fruit.
I love this video
thank you sir
Way better than my professor
Will Smith, will smith
I will smith
Therefor I am Will Smith
Cacophony
Invalid.
@@orenhausler6292
- Lukas Häusler is invalid.
- You are Lukas Häusler.
- Therefor you are invalid.
Invalid, and thank you a hundred times.
Would this argument be valid:
P1: A company mandating vaccination for its employees is involved in discrimination
P2: Google is mandating the COVID vaccine for its employees.
C: Therefore, Google is discriminating based on vaccination status.
That's not even an argument. First you have to learn how to structure an argument based on it's definition. An argument occur when one proposition implies another proposition and does contain reasoning. Bear in mind that, subject and predicate in each and all of those statements must share a relationship in order that to happen. For example:
A = B
C= A
So, C = B.
All man (a) are mortals (b)
John (c) is a man (a)
So, John (c) is mortal (b).
Notice, there is no 4th element of comparison. Just a, b and c and all of them are related to one another to form an argument.
Paul, could you please explain how the validity is affected if it is a compound syllogism and one or more premisses are analytic propositions: eg. P1: All symbols are made by minds (analytic premise) , P2: All codes are made of symbols (analytic), P3: Therefore, all codes are made by minds, P4: ASCII is a code, Conclusion: Therefore, ASCII was made by a mind. Is P3 also an analytic proposition because it follow from 2 analytic propositions? By "analytic" I mean necessarily true, as apposed to "synthetic" propositions whose truth depends on evidence.
So how do we determine if a premise is true?
You imagine the premises are true, and if with accordance with the premises the conclusion is true then it is a valid argument
You are awesome!!!
Why you give examples of not true things as valid arguments premesises what point am i missing there?
Response to the last question: Invalid. Association fallacy.
Looking at his Example:
1 All aliens speak english
2 (name) speaks english
C therefore (name) must be an Alien
is a Valid statement
Wouldn't the question at the end be a valid argument too?
I might be wrong af tho lol
it would still be invalid. al cars could also speack english: if name is a car, argumemt is not valid.
+John Doe I fucked up.
Invalid. It could be valid if P2 was “Square is a fruit” and the conclusion was “therefore square is a chair.” In order for the original argument to be valid we would need a premise that chairs can only be fruit and nothing else.
Thank you so much for your comment. I understood the video more after reading your comment. Thanks a lot.
Invalid, two objects that share one property doesn't make them identical as the property is not defined as property describing all properties of the object.
They could have explained the concept much better.
I will try to summarize the video in simple terms.
1) An argument is a list of statements that support a conclusion or answer a question.
2) A statement, in an argument, is known as a premise.
3) A valid argument is an argument in which all of the premises agree with each other, assuming that the premises are true. In other words, it’s valid when the premises do not conflict nor contradict the each other and we say the premises are true.
4) A valid argument does not identify if the argument is true or false, rather a valid argument only identifies if the premises support the conclusion or not.
Example 1:
P1: Bobby eats all foods that are red.
P2: Bananas are red.
Conclusion: Bobby eats bananas.
In Example 1, the argument is valid but not true because P2 is not true, yet all of the premises agree if we assume P2 is true.
Example 2:
Question: Is the world round?
P1: Bobby says the world is flat.
P2: Bobby is always right.
P3: The world has been proven to be round.
Answer: Yes, the world is round.
In Example 2, the argument is not valid yet true because the world is round but the premises don’t agree.
We can use valid arguments to find the best answer when our known information is incorrect or limited. We can then find better answers to our questions using another valid argument as we learn the correct or new information.
That’s why we should be humble and unbothered when someone criticizes our ideas and actions. What you think you know might be valid but not correct nor true.
Great video thank you!
Please what is the answer to the last video
U save my life 🙏
a conclusion being necessary means that the claim also conclusion is needed. think of it as applying for aa job and the interviewer says that you are necessary fir the job. you are needed because of your qualifications. inferencing here means to use the evidence being the premises and using them as reasons to make your claim. youre conclusion is what you strongly believe in and the premises are the because, they let us know why you think that. you could also work backwards by giving the claim 1st nd then using the premises to make convince us of what you claim. this happens only in valid deductions, the conclusion is based off of the premises.
On the academic level after conclusion is conceptualization. ..
If all fruit is a chair, and square is a chair, then square must be a fruit. If P1 was true and P2 is true, the validity of the Conclusion resides on if it is true, making the argument valid, or untrue, making the argument invalid. Review the video @ 4:05. False premises can produce a valid argument. If we use our conventional understanding on what distinguishes a fruit from a chair, then P1 would be classified as a false statement along with P2 based on the same principal between a square and a chair. However, if P1 and P2, even though we know the statements to be false, were in fact true, using a more ambiguous definition of the objects, the conclusion would in turn constitute as also being true. So in conclusion, the statement is VALID. (capitalized for visual effect, I am in no way yelling at you)
valid
the split and splat thing sound a lot like Hegel's philosophy...
how about the statements
Aliens speak English
Splot is alien
Therefore, Splot speaks English
It is confirmed valid but Americans also speak English? Must be invalid or i just dont get it?
Americans had nothing to do with it
Last argument is invalid. The truth of the premises are not relevant to the conclusion.
not valid. If P2 was 'Square is a fruit', and C was 'therefore square is a chair' then that would be a valid argument. But just because all fruit is a chair (a slightly dubious statement because of the grammar in my opinion,) that doesn't give us any information about square. Square may be, or may not be. We don't know.
Note : The statement : All humans are mortal is a conditional statement. It should properly be framed as : All humans are mortal, so far.
Not necessarily.
If we are defining humans as necessarily having the trait of being mortal, and a human is found that is not mortal, the logical conclusion is that this found being is, in fact, not human.
So:
- All humans are mortal.
- John is not mortal.
- Therefore, John is not human.
Sounds valid to me.
The terms, "mortal"and humans" first need to have an agreed upon definition. This if often difficult and controversial. Thinking about thinking
invalid, because the conclusion is false?
cmiiw
So logic assesses the validity of an argument and prior knowledge assesses the truth of it's premises... So one must use both logic and prior knowledge to assess the truth of a conclusion. Okay, okay I think I get it
The conculsion is the conclusion. I repeat what I wrote above, for less intelligent minds-the conceptualization is made after all the research was done or made. When a student have a conclusion, than can start the methods in research by branding them in their splendor: life standards, educational level, intelligence, healthy life style, hyginese...depends in what field you make the research. But all the way goes to... where?
To the ones that are scrambling their brains ... The answer at the end is that the conclusion does not add up logically. You can see it's invalid by breaking the pattern when u think in terms of logic (Although Im not sure it's the right way to interpret it) But yeah, logic..
i Really do not get that immortal part. How is all humans immortal??
And this is the fundamentals behind the majority of theoretical physics.
Nice
4:08 You said all the premises would be false, but P2 is true (or at least it was earlier).
good point, would anyone mind to explain?
How do you know that Iris Murdoch is a human? Couldn't this premise be also false?
good point, i was thinking this too
Wait i think i got it, if both the conclusion and premises are unknown to be true or false, the argument can still be valid, the only thing that matters is if the premises entail the conclusion, if one premise is true and the other false but both combined entail the conclusion then the argument is valid...I THINK
how does validity of an argument define?
I take you on another pathfinder. Imagine that you have done one study case for marketing and sales . You found an important article from 1945. That article does not have validity for todays life standards or life style. It does not have validity because the market today or now days does not have the same products like in 1945. You are making segmentation for your business postioning. It is logical for a 5 years old mind. It is education. Why do we need to stive to have dialogs with mental handicaps?
Invalid.
+Isaiah Edwards Its invalid, as it is not stated that all chairs are fruit, only that all fruits are chairs.
+RODO125 Thanks fam.
a splif is a splat
if a fruit is a splif
than a splaf is a sploof
am i wrong?
It is a Valid Argument.
@4:08 it is said that this is an argument with all false premises in it - but how is premise 2 ("Iris Murdoch is a human.") false? Is Iris Murdoch not a human?? (..obviously we know Iris Murdoch is a human)
Murdoch is human? I never heard
What I'm taking away from this is someone could have a totally valid argument, but it also be totally bullshit.
Yeah me too. The way I think of this is A + B = AB (Valid). A + S = AB (Invalid)
Invalid. Typical example of affirming the consequent.
I think it's valid
Invalid argument at the end, if all chairs were fruit it would be valid, but since all fruit are chairs, and square is a chair, the argument cannot logically conclude that.
P1 tells us that all fruits are chairs, not that all chairs are fruits. As such, p2 cannot prove the conclusion as it only tells us square is a chair, not specifically a fruit. So it's invalid.
even though all fruits may be a chair, not all chairs are fruits
Or may not be fruit at all
How are the people in the opening statement not using validity in the same sense? An argument is taking place and they are making a statement that "oh aha! you have finely made a valid argument that follows logical rules instead of fallacies and nonsense." They are using validity in the philosophical sense. They are not stating agreement with the argument just accepting that the person they are debating has finally formed a valid argument.
Of course, fruit cannot be a chair and a square is not a chair, we know this. However, if without a doubt the statement is ensuring all fruit is a chair then there is absolutely no way a triangle can be a chair (the premise specifically stated that a fruit is a chair) or that pizza can be a chair ( the premise specifically stated that a fruit is a chair). Given this information, the conclusion is a valid deductive argument because of the specific premise and conclusion. The question was "is the argument a valid deductive argument or an invalid deductive argument NOT if the argument was concluded by SOUND statements. Right? Wireless Philosophy
Oh! I know this one! Invalid! This is the fallacy of affirming the consequent or fallacy of the converse, if you will! :D
I’m literally a grade 11 high school student taking a grade 12 philosophy course. Send help.
Invalid. All fruits are chairs does not mean all chairs are necessarily fruit.
INVALID
Premises are TRUE
Conclusion is FALSE (Square may not be fruit)
Invalid. We don't know if all chairs are fruit.
Square could be a fruit, which makes it a strong inductive argument, but not a valid deductive argument.
Invalid be cause all fruits are a chair but some chairs could be fruits. Therefore chairs are chairs.
Wtf? Where's the answer?? I need someone to valid(ate) me!
Spliff is a splaff. Wtf! Clear simple wording or easier contexta would make a huge difference to landing this video.
Right? Wireless Philosophy
Premises is plural.
Where my Night Owls at? 🦉
Here 😅
Here ❤
the last one is definitely invalid
Urgh, surely this could have been explained better through the introduction of simple syllogisms? Or is the idea that the audience is afraid of algebra? Saying there are formal structures in which A is B; B is C; so A is C actually provides a basis for understanding the relationship between different statements through variables and functions, whereas repeating the 'If the premises are true the conclusion must be true' thing five times doesn't explain 'why' validity works at all.
There are many valid argument forms that are not syllogisms. Syllogisms are unfortunately limited to three-term sets of three categorical claims. Yes, formalism is ultimately required (this formalism is called logic, not algebra) to have a thorough understanding of validity. But validity really is (in a syllogism or other kind of argument) a conditional relationship between premises and conclusion.
math! If a = b and b = c, then a =c. If a = b, but b does not equal c, then a cannot equal c. :)
“It depends on what the meaning of the word ‘is’ is.”
I can't understand this thing and I have an exam tomorrow T_T
Who is to say a pencil can't be a chair too even though it is not a fruit which is always a chair? A square is a chair even though it may not be a fruit. But all fruit is a chair.
Invalid? Maybe valid if P1 was changed all chair are fruit
The last argument is invalid.
If all fruit are chair, and the square is chair, there is a possibility that square may not be fruit, even though it is chair.
invalid because fruits may not be the only thngs that can be chairs
How do psychology graduates make a living? genuine question lol
Invalid, even if all fruits are chairs doesn't entail that everything that is a chair is a fruit.
All spliff are splat