Philosophy Radio! drlabasham777's Podcast
Society & Culture:Philosophy
Hey logicians!
Wise ones all.
Here are two simple deduction problems. Well use the rules we outlined. Recall these. On opur Bb. So,
So let’s check this out. Easy. We have to get p all alone so we can get to q (1). But p is mixed up with r. So we break up their little chit chat with a rule. Disjunctive syllogism. Look up those rules of basic deduction. Here is one,
p v q
~p
So Q
or
p v q
~q
So p
But don’t forget “mp” ( also known as if BLANK then BLANK or "arrow" elimination)
P then q
P
So q
That gets us to step 5,
If we take out all the talk, it looks like this,
Here’s another one,
We need to find a way to ~q. Here we go. We got to get p v r,
So we do this: we add r to p: p v r. “Or Introduction” or v I
That gives us p v r, and p v r heads straight over to s by modus ponens. So we have s.
S gives us ~q by modus ponens (arrow elimination).
So q.
It looks like this, without all the talk-talk,
That's not too hard.
Cheers~
Dr. B
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