Logic

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One of the most common and important ideas present on this forum is logic. It’s also the idea most often abused, ignored, or warped. So I bring some questions to you all. What is logic? How do we determine whether or not an argument is logical? How can we be certain that logic itself is “true” or “valid”?

 
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Originally posted by Kasha4890:

One of the most common and important ideas present on this forum is logic. It’s also the idea most often abused, ignored, or warped. So I bring some questions to you all. What is logic? How do we determine whether or not an argument is logical? How can we be certain that logic itself is “true” or “valid”?

Just my humble opinion… logic is how people put together their thoughts and act to get a desired result/ effect.
The recipient can only assume or belief the claim of the subject and deduce if their act is logical or not. By that definition, the deduction and the questioned logic have no universal standard, only subjective. I can accept a logic is true and valid as long as it matched mine or matched the majority’s

 
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I think that logic cant be avoided and cant be ignored you could jump a fence and get bit in the rear and still gain logic we as humans continuously gain logic. You would determine if argument is logical if you didn’t no the facts if u did no them then its just a argument

 
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Originally posted by Vuteks:

I think that logic cant be avoided and cant be ignored you could jump a fence and get bit in the rear and still gain logic we as humans continuously gain logic. You would determine if argument is logical if you didn’t no the facts if u did no them then its just a argument

What language is that in?

 
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What language is that in?

Dunno. If you can’t translate then nobody can.

 
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I’m gaining logic right now!

Wait no sorry I lost it. Damn.

 
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Logic. Is our thought process. It’s how we interpret different situations.

If we see a car coming down the road. Logic says we wait till it is past until we cross the road. If we didn’t use logic we would just start walking out into the road.

 
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What if you were trying to die, it’d be logical to cross in front of it.

Different aims bring about different logic.

You could also just not give a damn, and not want to wait on the car and cross anyway, not really bothered if you get hit or not.

Not logical or illogical.

 
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Your logic can seem logical to you, but very illogical to another. It is a subjective issue, and will never change. In fact, I would find it very irritating if someone claims that points are refutable if they are “illogical”.

 
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As a computing scientist, logic for me must be able to be formalised into a mathematical structure. For an argument to be logical there should be a set of predicates which, using the standard logical tools (modus ponens/tollens and so on), derive the given conclusion.

 
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Logic is simply examining cause and effect and a relation between a number of statements. If a conclusion is logical, it will both be true and supported by its premises. When refuting logic, you must either show the conclusion to be false or that it is not supported by its premises.

 
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Originally posted by lord_azaral:

Logic is simply examining cause and effect and a relation between a number of statements. If a conclusion is logical, it will both be true and supported by its premises. When refuting logic, you must either show the conclusion to be false or that it is not supported by its premises.

Or simply that one or more of the premises are false.

 
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Almost everyone seems to be confusing logic with common sense… It is not subjective (only premises are possibly subjective), and its conclusions apply to all people.

 
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A. what’s with the posts Bastien?
B.I find logic to be finding answers, simple as that.

 
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Your logic can seem logical to you, but very illogical to another. It is a subjective issue, and will never change. In fact, I would find it very irritating if someone claims that points are refutable if they are “illogical”.

There’s even a term for that! It’s the argumentum ad logicam, or “argument from fallacy”, which consists of saying that a statement is false because the argument for it is fallacious. It is of course a logical fallacy.

Anyway, I don’t think this thread is going to go anywhere, because the nature of logic has been studied since the era of the ancient Greeks. Even if we were all as smart as Plato, there’s been over two thousand years of thought put in to this subject; we’re unlikely to tread any new ground here. Just go read the Wikipedia article or something.

 
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Logic is an area which requires strict discipline. To argue logically, one must be able to carry a point from a > z through a series of irrefutable steps. IF this can not be done due to impossibility / paradox etc, the argument is false etc. By approaching an issue/puzzle/problem in a logical fashion, we can get closest to the truth.
The question as to whether logic is “true” or “valid” applies to the tools one uses to reach conclusions. This is where the system breaks down as different people required different input to satisfy their need for proof.

 
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There’s even a term for that! It’s the argumentum ad logicam, or “argument from fallacy”, which consists of saying that a statement is false because the argument for it is fallacious. It is of course a logical fallacy.

Haven’t been too long into debates, so I wouldn’t know the names for it, but thanks for the link. Reminds me to look up some of those for use in the future.

 
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In my thinking I say logic is the process of thinking that concludes to the truth. The truth is a statement that applies to the whole universe. For example: I have in my hand an apple, if its true then if I ate it it should taste like an apple, If I threw it to somebody it should hurt like an apple, if I put it in a spaceship and fly it to another galaxy it should weigh like an apple.

 
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Originally posted by Syneil:

As a computing scientist, logic for me must be able to be formalised into a mathematical structure. For an argument to be logical there should be a set of predicates which, using the standard logical tools (modus ponens/tollens and so on), derive the given conclusion.

This is correct. Specifically regarding deduction, a “logical” argument is a well-formed formula— the conclusion follows from the premises with certainty. If the conclusion can be false and the premises true, it’s not a logical argument/is invalid.

Although propositional logic isn’t the only way to do it— it’s a bit weird for modal logic, how you set up a model, as opposed to semantics in normal logic.

 
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logic is argumtative causality.

just like in causality you have ‘cause’ and ‘consequence’, so in logic you have ‘premise’ and ‘conclusion’.

where ‘conclusion’ follows from simple addition of 2 or more premises by rules of basic algebra.

 
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Originally posted by Syneil:

Or simply that one or more of the premises are false.

Your argument can have valid logic without truthful premises. However, the sound argument has both valid logic and a truthful premise.

 
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Logic is, at the most basic level, simply doing cause and effect and making a series of “therefore” statements.

For example, let’s say lots of people get lung cancer after smoking.

Cause:Smoking
Effect:Lung Cancer

People have lung cancer after smoking therefore smoking causes lung cancer.

The most complex argument can be broken down into this.

 
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Originally posted by helltank:

Logic is, at the most basic level, simply doing cause and effect and making a series of “therefore” statements.

[…]

People have lung cancer after smoking therefore smoking causes lung cancer.


I’m quite sure that everyone who get lung cancer have walked at least once. Can i deduce logically that walking implies cancer lung? No. Why? Because logic is hard, it’s something totally different from that you were talking about.
 
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I’m quite sure that everyone who get lung cancer have walked at least once. Can i deduce logically that walking implies cancer lung?

Either you’re telling him he’s missing part of his argument or you don’t see what the missing part is. His post would have been much larger if he was going to explain everything about it. Of course it’s not as simple as “smoking —> lung cancer”. You start with a correlation. There could be a high correlation between smoking and lung cancer. This doesn’t prove any causation. It could just as much mean “lung cancer —> smoking”. It could also mean nothing. You will remove other factors, test on it, yadida. Any way, I’m sure you’re already knowing all of this and simply thought Helltank didn’t.

I’m looking back on my own posts in 2009 and my stance has slightly changed. It is true that any person can say something is logical or illogical, and at the same time disagreeing with the current definition of logic. So, at first, we’ll need a universal definition for logic. Having that, people can disagree with it as much as they like, all they’re doing is saying they want to use the same concept for a different definition (and a different concept for the same definition). Doesn’t change a thing. Next is the actual logic. A person can use a correct logical structure (cause: X, effect: Y), but it could still not be correct (cause: I walk, effect: people die). Is that logic? No, because it isn’t based on the truth. What is truth? Something that is scientifically proven. Will certain religious people accept science? No, so they won’t think science is the truth and as such they will think something is “logical” when using the Bible as quotation. This leads to very bad problems.

 
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This is what I’ve always though “Logic” is.
The universe is the ultimate realm of reason and logic. Things happen for reasons that can be explained.
So the most logical answer is the one that agrees with the universe in the most efficient and agreeable way.