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Does logic equal truth?

Skwim

Skwim

Veteran Member
Shad said:
Which is valid not sound.
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My bad, and corrected (actually deleted).

Valid is not soundness, it a validity. Soundness is separate from being valid. Valid is of form. Soundness is of truth.
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Actually, soundness means an argument is both valid and its premises are true, making the conclusion true as well.

Redhead {s} are dumb
Bob is a redhead
Therefore Bob is dumb

It is valid but the soundness is in question.
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Not in question at all. It's not sound because the major premise is not true. (I know a redhead who's quite bright).
 
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Shadow Wolf

Shadow Wolf

Certified People sTabber & Business Owner
Jayhawker Soule said:
Therefore? What we do know is that the appeal to ignorance is a worthless basis for any claim.
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But, very often, it is the only honest answer we can give.
Shad said:
Sorry you are completely wrong.
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No, I am correct. A logically valid argument is when the inference from the premises to the conclusion is affirmed. Whether or not an argument is logical or not is entirely independent upon the validity of the argument. I may have used the word "sound" in the more common usage, but I am correct in stating that a logical argument does not have to be factually correct.
Shad said:
However philosophy and logic are the ground work of every scientific field we have so introducing it prior to one's commitment to a specific study path would be a benefit.
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 Science, writing, law, engineering, anything involving research, pretty much anything you study is based on logic and enhanced by understanding logic.
 
Skwim

Skwim

Veteran Member
Shadow Wolf said:
No, I am correct. A logically valid argument is when the inference from the premises to the conclusion is affirmed. Whether or not an argument is logical or not is entirely independent upon the validity of the argument. I may have used the word "sound" in the more common usage, but I am correct in stating that a logical argument does not have to be factually correct.
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Just to clarify:

A "logically valid," or "valid" argument is one that takes a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false. In syllogistic logic there are 15 such forms. In speaking of valid arguments the qualifier "logically" is taken as a given and need not be used, OR if you're using "logical" as a synonym for "valid," the "valid" can be dropped.

A valid argument with a false premise.

All wine comes from cows
Merlot is a wine
________________
Merlot comes from cows​



Truth in an argument signifies that the premises themselves are true. Where a true conclusion follows from an invalid argument the truth is only a happenstance and not a logical deduction. It just happens to be true.

An invalid argument with true premises and a true conclusion:

All wines are alcoholic beverages
Merlot is an alcoholic beverage
_________________
Therefore: Merlot is a wine.​


Soundness indicates that the argument is both valid and its statements true.

A sound argument.

All wines are alcoholic beverages
Merlot is a wine
_____________________________
Merlot is an alcoholic beverage​
 
Shad

Shad

Veteran Member
Shadow Wolf said:
But, very often, it is the only honest answer we can give.

No, I am correct. A logically valid argument is when the inference from the premises to the conclusion is affirmed. Whether or not an argument is logical or not is entirely independent upon the validity of the argument. I may have used the word "sound" in the more common usage, but I am correct in stating that a logical argument does not have to be factually correct.
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No issue here. Just when people used the word sound in a thread about logic I expect it to follow the context of the OP thus use the term from logic rather than common language. Validity is what you were talking about, that an argue flows from premise to premise. Sound(ness) is if the premises are true and the argument is valid.


Science, writing, law, engineering, anything involving research, pretty much anything you study is based on logic and enhanced by understanding logic.
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Logic as a tool is so common in many fields it is a shame that it is never taught as a requirement as part of K-12. Which was my point.
 
Shad

Shad

Veteran Member
Skwim said:
My bad, and corrected (actually deleted).

Actually, soundness means an argument is both valid and its premises are true, making the conclusion true as well.
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Just me tripping up with people using the common mean rather than the context meaning. Ive done it twice already. I just like to keep everything within context since GL is trying to learn a bit about logic. With people switching from common language to technical then back it could cause confusion.


Not in question at all. It's not sound because the major premise is not true. (I know a redhead who's quite bright).
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Pretty much. I know a lawyer that is a redhead so there are at least two that refute the argument.
 
Shad

Shad

Veteran Member
Skwim said:
Wrong. Evolution is considered a fact, a scientific fact. Where theory comes in is in explaining how it works.
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My point was that in deduction theories do not qualify as facts as all theory are based on induction. Thus any argument using a theory is using inductive logic as well, supportive instead of soundness parameters.
 
Kilgore Trout

Kilgore Trout

Misanthropic Humanist
God lover said:
There are a number of logical explanations for the same reality.

If I show up at your house, logically I could have taken the bus, walked or driven my car.

Should the door opener assume they know which is the most logical way?
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After reading the thread, I think you're conflating "logical" with "reasonable."
 
leibowde84

leibowde84

Veteran Member
God lover said:
There are a number of logical explanations for the same reality.

If I show up at your house, logically I could have taken the bus, walked or driven my car.

Should the door opener assume they know which is the most logical way?
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No, course not. Logic is a tool for arriving at truth. It doesn't negate the erroneous nature of assumptions though.
 
9-10ths_Penguin

9-10ths_Penguin

1/10 Subway Stalinist
Premium Member
God lover said:
Thank you for coming clean.

Here's why I posted this question.

It seems like we can all use logic to justify our beliefs. There can be false truth claims backed up by a variety of logical explanations.

I beleive evolution is a logical explanation of why we and everything are here. I think a creator is a logical explanation of why we are here. My point is that logic can only take us so far before we need something else to find truth. We will never take our hands off the edge of the pool if we can't go where our logic won't let us.
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"Going where logic won't let us" is what we call guessing. Do you think that guessing is a reliable pathway to truth? Even if you serendipitously made a correct guess, how could you actually know that it was correct if you're beyond the reaches of logic?
 
dust1n

dust1n

Zindīq
Shad said:
Neither logic nor philosophy were K-12 courses during my youth. I believe it is a mistake to push these subjects into post-secondary education. One reason is the k-12 education's purpose is to introduce common knowledge which can be applicable to most career paths. However philosophy and logic are the ground work of every scientific field we have so introducing it prior to one's commitment to a specific study path would be a benefit. It is also applicable to most trade-skills but is not as apparent.
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Logic will help you complete math formulas, complete puzzles, write essays, think critically, etc. Eh, but what do kids need those things for.
 
Nakosis

Nakosis

Non-Binary Physicalist
Premium Member
God lover said:
There are a number of logical explanations for the same reality.

If I show up at your house, logically I could have taken the bus, walked or driven my car.

Should the door opener assume they know which is the most logical way?
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Truth is what you accept as truth. Logic is what folks use to pretend what they accept as truth is justified.

Suppose I tell you I road my bike. Even point to a bike and say there's proof. Well you're probably going to accept that cause you've no reason not to. Could all be a lie. Maybe even not my bike but you accept it as true because it seems reasonable enough to you.

So we accept something is true, based on whatever evidence seems reasonable and could be wrong about it being true.

I see the truth as something we create. It's accuracy to actuality is always going to be questionable. The fun thing is you can lie or manufacture evidence fool folks perceptions and convince them to accept the "truth" of something.

I pretty much get stuck questioning the truth of everything expecting at each moment coming across some new information that will change what I accept as truth. Kind of a fools to look for or accept any truth as absolute. So you find out what works for you and stick with it as long as it continues to work for you.

Just don't get mad whenever what you chose to accept as truth turns out not to be the truth. Wasted effort. Just revise whatever you accept as truth and get on with living.
 
Nakosis

Nakosis

Non-Binary Physicalist
Premium Member
Logic is a structured process of reasoning. Being structured it allows you to more easily identify your flaws in reasoning.

It doesn't guarantee the truth of your premise or the validity or correlation of your evidence. There are limits as to how far you can validate something and folks decide for themselves how far it is reasonable to do so.

Any premise is based on an earlier premise. You validate as far back as it seems reasonable to go but I think at some point the premise is validated by definition. That's conventionalism, the view that fundamental principles are validated by definition, agreement, or convention.
 
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