Should Logic Be a Required Course in Public High Schools?

[9-10ths_Penguin]

You said this:

Logic has a role, but formal logic in the "given that A is true, B is necessarily true and C is necessarily false" sense is often not much use in helping a person decide what's more likely true than false, what's plausible or implausible . . .​

Tell us what you comprehend from this:

A modal is an expression (like ‘necessarily’ or ‘possibly’) that is used to qualify the truth of a judgement. Modal logic is, strictly speaking, the study of the deductive behavior of the expressions ‘it is necessary that’ and ‘it is possible that’.​

Modal Logic (Stanford Encyclopedia of Philosophy)

It sounds to me that you're describing something like . . . modal logic.

We can talk about probabilities without invoking modal logic.

 

[Sanzbir]

If you find any claims that I've made on this thread that you believe to be erroneous, be sure to quote them and cite your sources to demonstrate their error. That's what I've done with your many ignorant claims, such as that one can deduce a true conclusion from false premises. And such as that this is a valid syllogism:

No reptile has mammary glands [True premise]
All frogs are reptiles [False premise]
Therefore no frogs have mammary glands​

It isn't. That's why you can't identify the middle, predicate and subject terms.

Study more, post less.

Oh come the heck on!! I keep going back to your own wikipedia source and quoting the heck out of it!!

"In logic, an argument is valid if and only if it takes a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false.[1] It is not required that a valid argument have premises that are actually true,[2] but to have premises that, if they were true, would guarantee the truth of the argument's conclusion. A formula is valid if and only if it is true under every interpretation, and an argument form (or schema) is valid if and only if every argument of that logical form is valid."

READ THE ARTICLE: Validity - Wikipedia

I honestly cannot believe you don't understand everything I have said. I've provided the words of your own dang sources enough times now!!

I refuse to believe you are that dense that you can't understand, after all the times I've repeated it, what the definition of "validity" is!!

I'm nearly certain by this point in time you fully understand that you were using validity wrong and you just don't want to admit it!!

Why?? When I was confusing the term soundness and validity way earlier in this thread I had the decency to own up to it!!

Stop this dishonesty!! You must understand what the term "validity" means by this point in time!! No one is that ignorant!!

Stop pretending to be an idiot!!

The subject term is clearly frogs. The middle term is clearly reptiles. And the predicate is clearly has mammary glands!!

And I refuse to believe you don't understand this basic freaking fact because it's the exact freaking same as your own argument just switching out the middle term from amphibians to reptiles!!

If you can see the parts of your own argument it's freaking obvious what the parts of my own are!! And I feel insulted that you ask me to demonstrate such a basic thing because it must be obvious for you!! This must be something you obviously understand!! You're just pleading ignorance now for who-knows-why!! Why are you claiming to not understand this thing?? I honestly don't get why you would pretend to be this ignorant and dense!!

Is it to get out of admitting wrongness even slightly?? Do you just not want to admit that you were mistaking truth, validity, and soundness??

Because if you don't want to do that, just go away and stop posting. Don't build a text-monument to your own stubbornness by pretending you still don't get it.

This is why you refuse to acknowledge the wikipedia article's "Socrates is Green" valid syllogism. Because it totally blows your definition of valid out of the water, and clearly shows my own syllogism to be valid!! And so you won't even acknowledge that I made that point or provided that source!! Cowardly!! Address my sources you coward!! My sources which I got from you!! Don't keep pretending I haven't given any!! Address the Socrates is Green syllogism!!

 

[9-10ths_Penguin]

If you find any That's what I've done with your many ignorant claims, such as that one can deduce a true conclusion from false premises.

- Premise: Justin Bieber has magical powers, including the power to paint the sky whatever colour he chooses.
- Premise: just now, Justin Bieber used this power to paint the sky blue.
- Conclusion: therefore, the sky is blue.

 

[Sanzbir]

If you find any claims that I've made on this thread that you believe to be erroneous, be sure to quote them and cite your sources to demonstrate their error. That's what I've done with your many ignorant claims, such as that one can deduce a true conclusion from false premises. And such as that this is a valid syllogism:

No reptile has mammary glands [True premise]
All frogs are reptiles [False premise]
Therefore no frogs have mammary glands​

It isn't. That's why you can't identify the middle, predicate and subject terms.

Study more, post less.

((Oh!! And don't think I didn't notice the fact you ignored the entire first half of my post to focus on the latter half!! It's obvious to me that it is likely because you recognize you can't hope to combat the first part, and so you've focused on the part you think you can object to!!

Even though the second half, the only half you're not too cowardly to address, was only an addendum!!

Don't think I didn't notice. You're ignoring the first half because you're too much of a coward to address a point that disproves your own ignorant statements about how it is impossible to deduce a true conclusion from a false premise!!))

 

[Sanzbir]

- Premise: Justin Bieber has magical powers, including the power to paint the sky whatever colour he chooses.
- Premise: just now, Justin Bieber used this power to paint the sky blue.
- Conclusion: therefore, the sky is blue.

I love you for making this post, man, but don't bother. I've stated things like that to him like five times now, and he just ignores the fact that the subject is truth and complains about the validity or soundness of the argument instead to try to deflect. If it didn't work the first five times, I don't see why he'll accept this obvious example on the sixth!!

 

[Nous]

- Premise: Justin Bieber has magical powers, including the power to paint the sky whatever colour he chooses.
- Premise: just now, Justin Bieber used this power to paint the sky blue.
- Conclusion: therefore, the sky is blue.

Is that supposed to be a deduction? I.e., it is supposed to be a valid syllogism? If so, identify it: Syllogism - Wikipedia

 

[Nous]

Oh come the heck on!! I keep going back to your own wikipedia source and quoting the heck out of it!!

"In logic, an argument is valid if and only if it takes a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false.[1] It is not required that a valid argument have premises that are actually true,[2] but to have premises that, if they were true, would guarantee the truth of the argument's conclusion. A formula is valid if and only if it is true under every interpretation, and an argument form (or schema) is valid if and only if every argument of that logical form is valid."

READ THE ARTICLE: Validity - Wikipedia

What you have quoted from the Wikipedia article is absolutely true. You cannot quote where I have said anything contrary to any of those statements.

It is your claim--that one can deduce a true conclusion from false premises--that is directly contradicted by the Wikipedia and every scholarly source on logic:

An argument is sound if and only if

1. The argument is valid, and 2. All of its premises are true.​

Soundness - Wikipedia

That means that those 2 conditions must be met in orderr to deduce a conclusion that is a true proposition.

That doesn't mean that a person cannot write 3 sentences that do not constitute a deduction--such as you did here:

No reptile has mammary glands [True premise]
All frogs are reptiles [False premise]
Therefore no frogs have mammary glands

--and state a true proposition as the last sentence. But, as I have noted repeatedly, you did not make a deduction with those three sentences. That isn't a valid syllogism.

Post less, study more.

 

[Nous]

This thread well proves that logic should be a required course in high school.

 

[9-10ths_Penguin]

Is that supposed to be a deduction? I.e., it is supposed to be a valid syllogism? If so, identify it: Syllogism - Wikipedia

It's a valid deduction, not written as a syllogism.

... but this is:

- all housecats are presidents of the United States.
- Donald Trump is a housecat.
- Therefore, Donald Trump is a president of the United States.

 

[Nous]

It's a valid deduction, not written as a syllogism.

... but this is:

- all housecats are presidents of the United States.
- Donald Trump is a housecat.
- Therefore, Donald Trump is a president of the United States.

Oops. OK, I'm the one who needs to go back to school. And eat crow for lunch.

Thank you, Penguin.

@Sanzbir, my sincerest apologies to you for all my insults. I was wrong. You are right.