What is logic?

[fast]

I would be careful not to mischaracterize an asserted argumentative conclusion as illogical just because the underlying reasoning may be flawed. Underlying logic is methodological reasoning. A reason with no rhyme may be illogical, but if there is a rhyme with your reason, then astray as we might go, it is not without some semblance of logical guidance.

We wouldn't say Spock is being illogical merely because he was mistaken. That his approach is grounded in having a method to his reasoning is mostly sufficient to demonstrate logical thinking. ("Method" might need a qualifier.)

ETA "systematic"

We can say that someone has his own logic so usage seems to support your view here. However, as far as I can tell, this expression is systematically somewhat disparaging. So what you're left with is someone using indeed a method or a system but one that we would characterise as inadequate.

I would also expect any method that's flawed, whatever the reason, to lead inevitably to contradictions. Such a method would therefore be an illogical method. But we would need specific examples to show that's true.
EB

We shouldn't take things to the extreme. If someone has a method that's easily demonstratable as repeatably flawed, then such a method would seem to reside outside of what would reasonably be characterized as logical. If you want to hold a system so high that it wouldn't be aptly labeled as logical because of potential flaws that might occasionally lead to unfortunate contradictions, then you're holding the bar of what constitutes systems as illogical too high. If two different people give strong yet different inductive arguments, we're not going to regard an inductive argument as not being apart of logical reasoning anymore than we'd disregard inductive arguments as being arguments for not guaranteeing conclusions. So, while any joe may have a system that may rightly be disregarded as logical, it is insufficient to regard the possibility of flaws that might lead to contradictions as illogical. It's an approach that needs to be reasonably appraised but not at such a high standard that also causes the kind of conflations as found between concepts of knowledge and certainty. We need to be balanced and let no one fall off either end of the ship. Hence, what stands good as something that's logical shouldn't be so loose that anything is let in yet not so tight that what's generally regarded as logical is left out.

 

[Speakpigeon]

Good.

You are alive.

Therefore you can hope to live a long life.

Also therefore, you'll die eventually.

Something like that. (sorry if I'm breaking the news to you)
EB

We are all going to die eventually.

Derail. It's not a logical conclusion.

Maybe you mean it's not logic because it doesn't make you happy.
EB

 

[Random Person]

We are all going to die eventually.

Derail. It's not a logical conclusion.

Maybe you mean it's not logic because it doesn't make you happy.
EB

We will die eventually. That's not even in contention.

 

[Speakpigeon]

I can't see how we could settle this.

You seem to believe that there are some sort of rules and that they have been defined by or before Aristotle. Personally, I've never heard of such rules and you seem to be the only one here in the know. So please, give us the reference to the scholarly work with a quote showing you are correct. If you can do that, you'll then have to explain why anybody should care about those rules.

I know, you won't do it, but, hey, I had to try.
EB

If you had engaged you might have seen.

If you tried to defend you might have seen.

I defended alright. You don't like it but I defended.

But since you did neither I can only say logic arrived via human interaction as a means to deal with real world questions.

It's origins are practical.

Derail. The OP is about what is logic, not its genesis or its use.
EB

 

[Speakpigeon]

We can say that someone has his own logic so usage seems to support your view here. However, as far as I can tell, this expression is systematically somewhat disparaging. So what you're left with is someone using indeed a method or a system but one that we would characterise as inadequate.

I would also expect any method that's flawed, whatever the reason, to lead inevitably to contradictions. Such a method would therefore be an illogical method. But we would need specific examples to show that's true.
EB

We shouldn't take things to the extreme. If someone has a method that's easily demonstratable as repeatably flawed, then such a method would seem to reside outside of what would reasonably be characterized as logical. If you want to hold a system so high that it wouldn't be aptly labeled as logical because of potential flaws that might occasionally lead to unfortunate contradictions, then you're holding the bar of what constitutes systems as illogical too high. If two different people give strong yet different inductive arguments, we're not going to regard an inductive argument as not being apart of logical reasoning anymore than we'd disregard inductive arguments as being arguments for not guaranteeing conclusions. So, while any joe may have a system that may rightly be disregarded as logical, it is insufficient to regard the possibility of flaws that might lead to contradictions as illogical. It's an approach that needs to be reasonably appraised but not at such a high standard that also causes the kind of conflations as found between concepts of knowledge and certainty. We need to be balanced and let no one fall off either end of the ship. Hence, what stands good as something that's logical shouldn't be so loose that anything is let in yet not so tight that what's generally regarded as logical is left out.

I don't know of any view of standard logic that leaves out valid syllogisms. On the other hand, the notion that induction is logical is entirely founded on loose language, i.e. there's really nothing similar between deductions and inductions beyond the fact that they are all statements that may be true or false. An induction is basically the statement of a belief founded on experience. Deductions, pace untermensche, are abstract in essence: All x that are F are G and a is F, therefore a is G. But you wouldn't want to claim that you know that all x are F because all the x you've seen in the world are F. So confusing these those modalities can only be problematic. You can call inductions logical if that amuses you but you should be so confused as to think that deductions and inductions belong to the same broad church. Unless you can show how they do?
EB

 

[Speakpigeon]

Derail. It's not a logical conclusion.

Maybe you mean it's not logic because it doesn't make you happy.
EB

We will die eventually. That's not even in contention.

Maybe for you it isn't. As for me, it is a fact that I don't know that I will die. Ever.
EB

 

[untermensche]

If you had engaged you might have seen.

If you tried to defend you might have seen.

I defended alright. You don't like it but I defended.

We certainly have a strong difference of opinion here.

You put forth a premise that keys can just vanish.

You act like we know nothing about matter.

By what mechanism can keys just disappear?

Giving a specific mechanism is engaging and defending.

Putting forth nonsense and defending it in no way is not engaging.

The point is, logic is a process, not an entity.

 

[Random Person]

We will die eventually. That's not even in contention.

Maybe for you it isn't. As for me, it is a fact that I don't know that I will die. Ever.
EB

You have won logic.

 

[fast]

The pressing divide is not between logical and illogical. Instead, the divide pertinent to this conversation is wider, which can be clarified as being between logical and not logical. If something is illogical, then it's not logical, but the inverse is not necessarily true. Because it's often true (but not necessarily true) that something that is not logical is illogical, a cited definition of the word "illogical" (that it means not logical) can be sufficient for a quick explanation, but because the nuanced "unnecessary" qualifier is overlooked, the definition is inadequate to capture the subtle difference.

Explaining the subtlety with some imagery may help. Whether something is logical/illogical has to do with a chosen path. If I take a logical approach and make no misstep in my journey, then I took a logical path and arrived at a logical conclusion. If I take a logical approach but take an unfortunate misstep or two along the way, then although I arrive at no logical conclusion, it's not therefore true I took no logical path, so illogical as my conclusion might be, the logical path I took is far different than a non-logical path.

For instance, if no good rationale, good reasoning, or good thought went into my approach, then underlying my conclusion has nothing to do with logic--and is neither logical nor illogical--and for the same reason, it's either logical or not logical.

To say something is illogical is to say more than most realize. It's also to affirm the path taken. Logic includes more than merely frogs that make it to the other side.

 

[Speakpigeon]

I defended alright. You don't like it but I defended.

We certainly have a strong difference of opinion here.

You put forth a premise that keys can just vanish.

You act like we know nothing about matter.

That's because I really don't know that keys cannot just vanish.

By what mechanism can keys just disappear?

I don't know and it doesn't matter to my argument that I repeat here for your convenience:

I don't actually know that keys cannot vanished into thin air therefore, for all I know, I may not be able to find my keys just because they have vanished into thin air.

Giving a specific mechanism is engaging and defending.

Putting forth nonsense and defending it in no way is not engaging.

I'm engaging but you're not paying attention.

The point is, logic is a process, not an entity.

I don't know what an 'entity' would be. But logic is not a process. I'm not going to say what I think it is since this thread is to ask other people about that and I don't want to influence anybody.


What is a process, though, is a particular reasoning, and so too a particular logical reasoning, which really seems to be what you are talking about but using the wrong words. So, there would be a process of reasoning logically about just disappearing keys. So, let's assume we agree on that bit. The question remains of what might be logic itself. Any idea?
EB

 

[untermensche]

That's because I really don't know that keys cannot just vanish.

Saying you don't know something is not a defense.

A defense is giving a way it could possibly happen.

Keys could suddenly vanish due to X.

And if X is "all present "laws" of the universe could instantly change" then sure.

But then anything can be defended in this way. It is a system with no discrimination. Worthless in other words.

When you propose something could happen you have to use known mechanisms. Or propose a mechanism based on actual evidence.

I don't actually know that keys cannot vanished into thin air therefore, for all I know, I may not be able to find my keys just because they have vanished into thin air

Again, not a defense if it is applicable to any statement made.

Not knowing something is not a defense of proposing something.

To propose something you must know something.

But logic is not a process.

What is a process

A process is two or preferably many more than two human minds engaging. It is not one mind saying they know but won't say.

 

[Speakpigeon]

A process is two or preferably many more than two human minds engaging.

Ok, so give me a realistic example of such a process, real or invented.
EB

 

[DrZoidberg]

Please give a short description of whatever it is that you think deserves to be called logic.
EB

It's exceedingly complicated. I remember a logic lecture at uni and my brain was bleeding through most of it.

Just read up on axioms. All axioms rest on logic. So they have to start by defining, and proving, logic itself.

https://en.wikipedia.org/wiki/Axiom

Any simple answer will be flawed

 

[Phil Scott]

Apologies for the shameless plug, but I have a rambling post on definitions and axioms here, going back through some of their history in mathematics from the Greek Elements to modern formalisations of mathematics.

 

[DrZoidberg]

Apologies for the shameless plug, but I have a rambling post on definitions and axioms here, going back through some of their history in mathematics from the Greek Elements to modern formalisations of mathematics.

Shameless plugs of that quality are always welcome. Welcome to the forum.

 

[Juma]

Please give a short description of whatever it is that you think deserves to be called logic.
EB

It's exceedingly complicated. I remember a logic lecture at uni and my brain was bleeding through most of it.

Just read up on axioms. All axioms rest on logic. So they have to start by defining, and proving, logic itself.

https://en.wikipedia.org/wiki/Axiom

Any simple answer will be flawed

Its the reverse: all logic rests on axioms.

 

[Phil Scott]

Apologies for the shameless plug, but I have a rambling post on definitions and axioms here, going back through some of their history in mathematics from the Greek Elements to modern formalisations of mathematics.

Shameless plugs of that quality are always welcome. Welcome to the forum.

Cheers! I'm actually an old member from 2003, but haven't been here since it migrated from Internet Infidels.

 

[iolo]

I remember listening - on Radio 3, I think - to a formal discussion conducted according to the rules of scholastic logic, after the mediaeval fashion, on nuclear disarmament. It was clear, unemotional and fascinating, and came out with an absolutely clear victory for getting rid of the bomb.

 

[DrZoidberg]

Its the reverse: all logic rests on axioms.

It's worse. It's fundamentally circular.

 

[untermensche]

A process is two or preferably many more than two human minds engaging.

Ok, so give me a realistic example of such a process, real or invented.
EB

One mind can't do it.

It takes two or more minds engaging towards practical goals.

How do we kill that rabbit?

If you do this then the rabbit will do that.

Then if I do this the rabbit will do that.

Then you can kill it.

You see how "if/then" conceptions flow from this kind of thing.