Posted by alexandra_k on May 17, 2005, at 23:22:08
In reply to Re: couple more: » Larry Hoover, posted by alexandra_k on May 16, 2005, at 22:48:40
Your answers are correct :-)
Some of them were hard.
I get what you mean about your brain aching...
Mine ached an awful lot to start with.
There are 'handy tricks'(formal or mechanical proofs) to tell whether an argument is invalid or valid. But most people can tell without having to resort to proofs when the arguments are relatively simple (as you did):-)
> (g)
> (P1) Either it is raining or it is wet
> (P2) It is not wet
> ____________________________
> (C) It is rainingIs valid, like you said.
(P1) Tells us that it is either true that it is raining or it is true that it is wet.
(P2) Tells us that it isn't wet.
So... In order for (P1) to be true (which we are asked to assume) It just has to be raining.> (h)
> (P1) If it is snowing then I am cold
> (P2) I am not cold
> ____________________
> (C) It is not snowingThis was a harder one, but it is valid, like you said.
(P1) tells us that if it is true that it is snowing then it just has to be true that it is cold.
(P2) tells us that it isn't cold.
It cannot be true that it is snowing and not cold or this would contradict (P1) So it cannot be snowing.I'll do some more.
Maybe later today or tomorrow...
But once again... No obligation.
:-)
poster:alexandra_k
thread:498245
URL: http://www.dr-bob.org/babble/social/20050513/msgs/499251.html