Please help I am very lost
1. EvV
2. [(EvO)vV]>~(V>M)
/E
This is not a valid argument. That's because we can show that
the conclusion can be false while both premises are true.
We start out by putting a f above each E, that assumes
the conclusion E is false.
f
1. EvV
f
2. [(EvO)vV]>~(V>M)
f
/E
Now we see if we can put t's or f's above V, O and M so that both
premises are true. If so we will have found a counter-example.
The first premise can only be made true by choosing V true. So
we put t's above all the V's
f t
1. EvV
f t t
2. [(EvO)vV]>~(V>M)
f
/E
Because V is true, [(EvO)vV] will be true regardless of
what truth value we assign to O, so let's arbitrarily assign
t to O.
f t
1. EvV
f t t t
2. [(EvO)vV]>~(V>M)
f
/E
Sinve [(EvO)vV] is true, ~(V>M) must be true.
That means that V>M must be false, thus M must be false.
We put f above M
f t
1. EvV
f t t t f
2. [(EvO)vV]>~(V>M)
f
/E
So as you see we have found a counter-example to this
argument which shows that it is not valid. We have exhibited
a case where the conclusion is false yet the premises are
both true.
If you haven't studied showing an argument invalid, then
you may have copied something wrong.
Edwin
