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/sci/ - Science & Math

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11829684 No.11829684 [Reply] [Original]

how do we know that logic is true?

>> No.11829703

>>11829684
good question.

>> No.11829733

Logical validity and truth are not the same thing.

>> No.11829779

inference is just a way of rewriting the same sentence. it's like a synonym. if it's the same sentence both times just written differently, then truth value has been preserved.

"an unmarried man" can be written as " a bachelor"
is the same as saying
an unmarried man is a bachelor

so if john is an unmarried man
and an unmarried man can be written as a bachelor
then john is a bachelor

>> No.11829784

>>11829733
Based

>> No.11829786

>>11829684
the same way we know Allah exists: you can feel it's right

>> No.11829793

>>11829684
We don't know it, we assume it. That's what axioms are

>> No.11829795

>>11829684
because it’s defined to be

>> No.11829817

>>11829684
we know it's not "true" and instead just made up games that occasionally map onto phenomena that that have some coherence to them

>> No.11829837

>>11829684
>how do we know that logic is true?
What logic? Today I woke up believing in GCH, but I'll go to sleep thinking that in the end I prefer stuffing many cardinals between the puny countable and the schizo uncountable.

>> No.11829867

>>11829684
There's probably no objective way to prove any logic right. It just has to be accepted by as many smart people as possible, and even then it can later on be pointed out to be wrong. With time we should gravitate closer to the elusive objectively valid logical rules. Math is a good example of this

>>11829779
How does this answer the question?

>>11829817
Logic has nothing to do with phenomena - it's a priori

>> No.11829874

>>11829684
Logic isn't truth.

>> No.11829880

>>11829684
It's axiomatic.

>> No.11829881

>>11829874
>>11829733
Care to give a short definition of both, then?

>> No.11829890

>>11829684
logic is just a system we made up. whether it's bound to reality is another question entirely

>> No.11829891

>>11829867
>How does this answer the question?
maybe read a logic book

>> No.11829912

>>11829837
That's not what GCH means.

>> No.11829921

>>11829881
>Asking anyone other than OP to define OP's terms.
retard

>> No.11829922
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11829922

>>11829684
I've read this and stopped caring.

>> No.11829929

Brainlet question:
Can formal logic be categorized as a metalanguage?

>> No.11829936

>>11829921
If you claim that two things aren't equal, you naturally should have some kind of definition for them also
t. logic

>> No.11829937

>>11829929
Anything that parses a language is a metalanguage. The subset of English words describing English words is a metalanguage of English.

>> No.11829945

>>11829936
You omitted OP from your cross-examination. The peanut gallery rules bad faith.

>> No.11829955
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11829955

>>11829922
Reminder that Wittgenstein retracted his theory of private languages in Investigations of Philosophy.

>> No.11829976

>>11829733
based
if pigs can fly, then i am king is a true statement

>> No.11829994
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11829994

>>11829684
I don't know, Anon, how do we know that facts are true?

>> No.11829996

>>11829976
Prove it.

>> No.11830011

>>11829996
pigs cant fly. therefore the statement is always true.

>> No.11830015

>>11829937
Thank you anon

>> No.11830127

>>11830011
>pigs cant fly.
Prove it.

>> No.11830309

>>11830127
Prove “Prove it” applies to the expression “pigs can’t fly.”

>> No.11830312
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11830312

Didn't.. didn't Godel say we can't kno nuffin??

>> No.11830369

>>11829922
is he any similar to nietzsche?

>> No.11830371

>>11830369
no
nitzsche was a novelist at best compared to him

>> No.11830996

>>11829733
>>11829994
It depends on your definitions. Truth ought to be the demand that statements expressed in language accurately represent the physical world. I can't think of anything that justifies truth other than normative statements like this, which is ultimately unjustified abstractly, but it is readily apparent from living in the world that it must be so.