Crosswords2 mins ago
QM you are mustard at this
4 Answers
Please take a look at my poodle question a couple below
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A syllogism is really a three-part statement consisting of a major premise, a minor premise and a conclusion that can be drawn from these. For example...All humans are mortal...I am human...therefore, I am mortal.
Your poodle-siituation consists of only two parts which are essentially unrelated and which do not lead to any logical conclusion. You could easily make the third element...Most dogs bark...or just about anything else that's true of dogs. There would still be no significant logical sequence.
How about the following rather?...
All poodles are dogs...some dogs are Alsatians...therefore, not all dogs are poodles.
Your poodle-siituation consists of only two parts which are essentially unrelated and which do not lead to any logical conclusion. You could easily make the third element...Most dogs bark...or just about anything else that's true of dogs. There would still be no significant logical sequence.
How about the following rather?...
All poodles are dogs...some dogs are Alsatians...therefore, not all dogs are poodles.
saying it is not a question..I dont think helps
all occurs in the sentence and it looks as though you will need a universal quantifier - wow ! use an upside down A !
but say instead, all poodles p
dogs q,
then all poodles are dogs would be p -> q
and dogs are all poodles would be q -> p
and and and all poodles are dogs but not all dogs are poodles would be
[p->q] -/> [q->p]
and there is nothing wrong with that, that is true
See Copi, you prove it with a truth table
the converse,
[p->q] -> [q->p]
I am afraid is NOT true and you prove its untruth with a truth table - see Copi again.
and then and then and then, the big thing about sentence logic- well I am sorry you did post this twice, so you are getting twice the answer, and twice the quite nubing boredom if you are not into this - is that the true sentences are things called tautologies,
and so with the rules as they stand, you can only prove other tautologies - perhaps not as useful as you may think - and not only that , if it aint a tautology, then you wont be able to prove it. This is a concept called completeness. Sentence logic is complete
I think COpi's book ends there, with the immortal words, now buy my book on first order logic
all occurs in the sentence and it looks as though you will need a universal quantifier - wow ! use an upside down A !
but say instead, all poodles p
dogs q,
then all poodles are dogs would be p -> q
and dogs are all poodles would be q -> p
and and and all poodles are dogs but not all dogs are poodles would be
[p->q] -/> [q->p]
and there is nothing wrong with that, that is true
See Copi, you prove it with a truth table
the converse,
[p->q] -> [q->p]
I am afraid is NOT true and you prove its untruth with a truth table - see Copi again.
and then and then and then, the big thing about sentence logic- well I am sorry you did post this twice, so you are getting twice the answer, and twice the quite nubing boredom if you are not into this - is that the true sentences are things called tautologies,
and so with the rules as they stand, you can only prove other tautologies - perhaps not as useful as you may think - and not only that , if it aint a tautology, then you wont be able to prove it. This is a concept called completeness. Sentence logic is complete
I think COpi's book ends there, with the immortal words, now buy my book on first order logic
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