Logic 101

[Captain Griffen]

Since you guys so clearly need it...first, some terms (iff means if and only if):

Proposition - a statement that is either true or false.

Set - a group of objects, ideas, whatever, in which the order does not matter.

Consistency - a set of sentences is consistent iff there is at least one assignment of true or false to propositions contained in the set such that all of the sentences are true (note that some propositions included in those sentences may be false).

Argument - contains a set of sentences, the premises, which are assumed to be true, and a conclusion which should be derived from the premises.

Validity - an argument is valid iff there is no assignment of true or false to prositions contained in the conclusion and the premises such that all of the premises are true and the conclusion false. Inductive arguments cannot be valid, but may by assumption be justified (although we don't know for sure how). Propositions cannot be valid. Tautological sentences (ie: those which cannot be false under any conditions) are logically valid, but no other sort of sentence is.

Things such as consistency and validity are technical terms, and have a very clearly defined use in the English language. Please learn to use them correctly.

I might also do some stuff on logical fallicies.

 

[Kwah]

Philosophy course fun, Griffen?

Anyway. Tautologies seems to be a big one here.

 

[PurplePoot]

Anyway. Tautologies seems to be a big one here.

Tautologies are big at the hive because everyone likes tautologies or dislikes them. This leads to criticism of those who do.

Hidden

(Yes, that was intentional)

 

[WILL THE ALMIGHTY]

I disagree because my beliefs say otherwise.

Beat that.

 

[Captain Griffen]

Tautologies are big at the hive because everyone likes tautologies or dislikes them. This leads to criticism of those who do.

Hidden

(Yes, that was intentional)

That's not a tautology. P or not P is a tautology, but the opposite of a statement is not its negation (not P).

 

[~Void~]

I disagree because my beliefs say otherwise.

Beat that.

I disagree because you're wrong.

BEAT THAT SHIT.

 

[WILL THE ALMIGHTY]

That's a tautology lol

(I used a fancy word!)

 

[Kwah]

No it isn't.

Because Void could agree with you, even if you are wrong.

AMRITE, Griffen?

 

[PurplePoot]

That's not a tautology. P or not P is a tautology, but the opposite of a statement is not its negation (not P).

Got me there. It was originally much more fail so I attempted to clean it up, although I clearly failed.

 

[Restor]

"This sentence is a lie" - O holy shit, neverending loop, all universe is going to crush...

 

[Kwah]

No, not at all.

 

[TheDivineBoss]

Argument - contains a set of sentences, the premises, which are assumed to be true, and a conclusion which should be derived from the premises.

No need to worry, I am just confirming his claim.

 

[Devine]

You all fail and I win because the pasta monster told me.
I'd like to add that logic is totally irelevant in this case because logic is totally irelevant in this case.

 

[Mechanical Man]

What is the word for the opposite of tautology? I know the word in my language, but not in english

 

[PurplePoot]

Something that contradicts itself? An oxymoron.

 

[Captain Griffen]

What is the word for the opposite of tautology? I know the word in my language, but not in english

Contradiction. Logically false, as opposed to logically true.

 

[Mechanical Man]

Just wanted to know the official naming, dictionary throws multiple words out.

 

[Kwah]

I just found that sitting on my desk. Griffen, gtfo my house.

EDIT: That'd be the Penguin Publishing Dictionary of Philosophy.