8.1 Predicate Logic: Symbols & Translation

[@amytisa]

I really wished that you were my professor. After watching this I realized that I didn't learn no shit in my class, and I have final exam tmrw. so thank you so much for this, very helpful.

[@okayypaulaaa]

I come here to watch your videos then go read and it’s so much easier. Thank you!

[@hellokittykaren007]

I am taking a class that uses this book as an online course. I watch these videos every week. They have helped tremendously. I have shared the link with my class, and the teacher thanked me for it. I appreciate this!! So f*ing much!!

[@sadaquekhan]

Do you have pdf of the book he is using ? can't seem to find it online

[@hellokittykaren007]

Sadaque Khan it was the book required for my class so I rented it

[@sadaquekhan]

Karen Ferrel Do you remember the name

[@moviesbooksandphilosophy4219]

I have watched all videos till here of logic in the last one month. And I am prepared as hell to ace my exam. (Something I used to avoid studying cuz it was so difficult when read in the book). I hope someday I'll see you somewhere and that day beers on me... Thank you from India

[@JB-qh3dn]

such an amazing lecture!! thank you so much Prof Thorsby.

[@MVParis19]

years later, and STILL helpful. thank you

[@gabrielvalderrama6035]

What a great video. Very comfortable to understand!

[@kaylamonique3975]

"Egomaniacs are not pleasant companions. Probably a lot of people know this, especially people married to Philosophers." 🤣👏👏 hahaha I wasn't expecting to spit my coffee out on my homework in a Philosophy class 🤣 bahaha oh man, I love it...

[@ThinkingThomasNotions]

Thank you, Mark: This video, besides fore being characterized by your usual lucidity, was very helpful in clarifying for me the grades of distinction among the categorical, propositional, predicate (and by implication, modal) logics. In fact, before this video, I had yet to encounter an explicit sketch of those distinctions.

[@Subhadebu]

This is what lockdown made my youtube feed come with, and I'm surprised that I'm fairly not bored. It's reminiscent of set theory

[@parizer1983]

50:08 The sentence does not specify red apples. The sentence is perfectly valid with conjunction between Green and Tasty because the exsistential quantifier can refer to a green apple. My opinion.

[@malteeaser101]

Marko Savic He interpreted it as 'some apples are green and some apples are tasty'. There may exist a tasty apple and a green apple, but there doesn't have to exist a tasty green apple. Most people who use that sentence probably mean that there does exist an apple that is both green and tasty, though.

[@madrona888]

Excellent lecture!! I was honestly worried about understanding after simply reading the chapter. The only way I have been able to complete the exercises (in general, any chapter) are after watching your lectures, and being able to read, or translate the statements and symbols the way you explain them. So thanks again.

[@tomfletcher1735]

Dude, thanks so much! You've really helped me decipher my longwinded textbook. Awesome teaching style!

[@tomfletcher1735]

soz, I mean professor

[@mauriciorodriguez918]

In the peaches example (51:10) if the norm is that we take disjunction as an inclusive disjunction unless is not the contrary specified, that notation means that a peach can be edible and rotten at the same time, I think a more precise interpretation can be this: “(x) {Px > [(Ex v Rx) • ~(Ex • Rx)]}”

[@Crack3rJack3d1]

Thank you so very much for this wonderful demonstration of logic good sir!

[@inadaizz]

Thanks for the upload sir.

[@asseflas]

you are the best, thank you!

[@bae7604]

This is a lifesaver

[@Supermario0727]

I understand that with 1st Order Predicate Logic, you can notate categorical logic with propositional symbols and universal quantifiers, but assuming you used Categorical Logic, how would you notate a universally argument?

[@israali5414]

thank you for this awsm video

[@tronagar]

If you don't mind a question, is it ok to combine predicate and non-predicate logic in the same expression? for example would ~A&Cu be a valid wff?

[@PhilosophicalTechne]

That is a great question. I think the answer is no (at least in general). In order to make the two systems work together, every expression needs a variable (or subject), even if there is no quantifier. I think you could create a system in which this would be possible, but you would need to introduce more rules for the introduction and elimination of expressions without a name.

[@aseltas.]

What do you mean tronagar? Can you explain your question?

[@eggleaves3597]

Early on it's said that a predicate is a quality that is attributed to something. Is this compatible with it being the attribution of a quality to something or indeed an attribution of a quality to nothing?

[@JB-qh3dn]

Why and how "only close friends..." is a universal statement?

[@dtopaloglou]

I believe it's a shorthand notation.

[@vincentmack37]

why don't you use the upside down A for the universal quantifier? is it not necessary in the states?

[@aRoamingDuck]

+vincentmack37 that's what I was wondering, and had a little confusion (I forgot the universal quantifier was the upside down A) and he was just using "x"

[@PhilosophicalTechne]

Hi Vince, Let me see if I can answer your questions. Standard professional practice requires that we use the symbol for the universal quantifier. The textbook used in the video series is an introductory textbook in which the symbol is merely superfluous. So, in the spirit of simplification, the Hurley textbook dispenses with it. In an advanced logic course you would want to use it.

[@sadaquekhan]

It adds more confusion, in my honest opinion. Also, I believe the majority of the people who are learning about predicates are using the upside "A" notation. '

[@famketheron7475]

You saved my day! Thanks a tonne.

[@SinisterRainbow]

"Some apples are Green and Tasty" -- why do you assume inclusive disjunction for Green and Tasty? If I said, "I like some tables that are flat and have legs" I do not mean I like some tables that are flat or some tables that have legs or both. Am I speaking natural English incorrectly by saying this? If not, how do you derive the context of what is said from a single sentence on a single sentence? It seems to me we derive meaning from an overall picture, and that it becomes ambiguous, at times, in single sentence statements.

[@Ataraxia-vz5vx]

You have the correct understanding. For some reason he made a mistake with the inclusive or. He did it again with the rotten peaches example. ((AvB) & ~(A&B)) is the exclusive or, not the inclusive or (AvB). There's a reason they call it inclusive or: you're *including* the conjunction. Exclusive or *excludes* the conjunction. Anytime you symbolize 'or' or 'either...or', you should carefully examine the meaning of the sentence to see if it makes sense that it was meant that both could be true at the same time. Examples: "Either you choose to be on time{A}, or you choose to find another job{B}" -> exclusive or (if not A then B) "Either you let me go, or I will scream" -> same, exclusive "Either John or Mary can go to the meeting" -> tricky, depends on if there is a pause after John. No comma after John, so I would say inclusive "Matter exists or it doesn't exist" -> clearly exclusive despite the absense of 'either' "I don't like radishes or cauliflower" -> neither/nor in disguise, ~(AvB) inclusive But everyone makes mistakes, and I won't berate him because this is good information and an otherwise awesome video.

[@villejunttila1425]

Ataraxia6746 Are you allowed to have an exclusive or inside a universal or particular expression i.e. say "either all lions are mammars or they are not mammals" can you say: (x)[Lx -> (Mx v -Mx)] or do you have to put the exclusive disjunction outside the expression like with propositional logic: [(x)[Lx -> Mx] v (x) [Lx -> -Mx]] & -[(x)[Lx -> Mx] & (x)[Lx -> -Mx]] Would really appreciate help as I have an exam soon.

[@bryanjohnson1125]

Ville Junttila the - [ (x)[Lx -> Mx] & (x)[Lx -> -Mx]] is always going to equal - [ 0 ] == 1 so not sure why you need this... The commutative property should always be correct -- so.. (x)[Lx -> (mX v -Mx)] == [(x)[Lx -> Mx] v (x)[Lx -> -Mx]] they say the same thing.. don't know if the notation is correct... Don't know if you can write for example: (x)[ (Lx -> Mx) v (Lx -> -Mx)]

[@villejunttila1425]

Bryan Johnson Thank you so much! Our lecture notes have nothing on exclusive disjunctions though they're on the sample exam papers, and our lecturer doesn't respond to emails. If it's not too much to ask there's still one thing i'm unsure about. If there's 2x conditionals and a conditional conclusion. For example: If all vampires hate all zombies, and all zombies hate all vampires, then if Bob is a zombie and a vampire then he hates himself. (x)[Vx -> (y)[Zy -> Hxy]] & (y)[Zy -> (x)[Vx -> Hyx]] -> [(Zb & Vb) -> Hbb]??? It starts to look a bit like propositional logic. At first I thought I should just treat them as separate premises and conclusion like in QL. Where V: Vampires Z: Zombies H: Relation of hating b: Bob

[@bryanjohnson1125]

It's been awhile since I've done this, I don't want to give any other opinions where I'm unsure so I'd find a logic forum and ask some one currently involved and more confident.

[@YouAndWhoseTube]

You can have a red apple that's green and tasty?!

[@Supermario0727]

Duh! :P

[@AlbumReviewChannel]

The fifth edition uses Morgan Fairchild. :)

[@TheNiso84]

why is it that you use "x" as universal quantifier instead the turned A "(∀x)" ?

[@abhinnshyamtiwari2739]

I guess just like the hypothetical conditional sign is of two type (just an opinion)

[@thealexanderharrold]

Mark you're a top lad. I still don't understand this shit though.

[@jwasily]

Sir, What is the software you use to make this video?, thanks.

[@FluxProGaming]

Not sure why you are not specifying what your domain is. You're simply stating if X exists in the universe. But it should be that our domain is all apples in the world and G(x) AND T(x) should you statement. A(x) for apples. Unless it was x is all fruits in the world, you would add the A(x) to indicate that x(fruit) is apples.

[@sadaquekhan]

What book are you using?

[@BalkanixGaming]

Hey can anyone help me with this translation, pleaseee? "To pass the SEG exam the students have to obtain grade 5 to all the three evaluation forms: laboratory, test, final exam. If one of these grades are below 5, even if the others are higher, the student fails."

[@malteeaser101]

Did you think of an answer after?

[@mrMMA916]

Almond I love you

[@mkatseal]

Please remember not to write behind your head.

[@sadaquekhan]

Does anyone have a pdf of the book he is using ?

[@entivreality]

You can find it on Aplia/cEngage: Hurley's A Concise Introduction to Logic.

[@sadaquekhan]

Can't find it online. Could you drop a link in the comments or message me ? Thanks in advance.

[@entivreality]

www.cengage.com/search/productOverview.do?N=16&Ntk=APG&Ntt=96889247910880680281642871993910461442&Ntx=mode%2Bmatchallpartial

[@entivreality]

That's an online version that I used for an online class recently. I'm not sure how it would work without an instructor, but in my course, it came with graded and guided practice problem sets for each chapter.

[@dpbeyond17]

your awesome...right!. haha awesome vid .

[@noamatatov6220]

THANKS MARK :)

[@namanjyotsingh2164]

welcome😉

[@JoeOG]

I laughed when you commented on Catherine Zeta Jones and Julia Roberts. Only people who know predicate logic would understand that the author basically insulted her by replacing her in the latest edition because he thinks she isn't as attractive (accidental... or is it?) Maybe Julia Roberts is not Julia Roberts anymore because she was attractive and now she is not attractive. Assuming of course that attractiveness is an essential quality of Julia Roberts, he indirectly proved that Julia Roberts is not worthy of being in a propositional logic statement within a textbook because p & ~p.

[@JoeOG]

Btw, you're awesome.

[@Inquiry20]

+Joseph Grant I respectfully disagree, (Ex)(Bj) :P (There exists 'J'ulia Roberts that is 'B'eautiful.) IMHO older or not she's still beautiful and a beautiful person on the inside. Changing it didn't prove her not worthy, just shows he changed it and doesn't prove his motive at all. I think you are going on a fallacy because of S > P, P therefore S This can be wrong if there is another reason for P that is not S. ;) I don't know what the name of this fallacy is, false cause usually in real life arguments, there is a special name for this I think in logic which starting out in logic they teach that the inverse is valid but I could think of a myriad of examples that show it wrong. If it rains Socrates will use an umbrella. Socrates uses an umbrella, therefore it rained. Maybe the sun is bright and he's using the umbrella to shade himself. meaning ~R thus invalid argument. I noticed this when I first started learning categorical logic with modus ponens and modus tolens, etc and took awhile until I found someone that addressed the problem. I would mess up on Truth tables and such because of this starting out and not sure why they don't address this fallacy from the start. That was back many years ago in college logic 101 class, hopefully they are teaching it can be a fallacy now. As for the vids Mark makes they are great!

[@FeriaDamisela]

Thanks. :D It really helps. But please don't make it too long. :( Still, it's okay :D

[@abrilthom895]

senator wilkins will be elected only if he campaings. Is bad translatede into predicate logic the stuff the textbook says is If senator wilkins is elected then he campaings. But put the sentence the senator wilkins will be elected is like is a condition then he makes campaign is the consequence . Like is he is not elected he will not campign. But the sentence is the opposite, If he campaigns or not it depends on being elected

[@francescopiazza4882]

Translation makes me crazy...