An argument is valid if it is impossible for its premises to be true while its conclusion is false. In other words, the conclusion must be true if the premises are true. An argument can be valid even though the premises are false.. here..
premise1: If Ram is married then he is sad
premise2 :If he is sad then he does not watch TV
premise3:He doesnt watch TV.
conclusion: Therefore Ram is unmarried."
A =Ram is married
B = he is sad.
C=he does not watch TV.
premise1 : if A ,then B.
premise2: if B , then C.
premise3: C
conclusion: therefore,not A
all the 3 premises are true but conclusion is false...
therefore argument not valid..
we can also take a counter example to prove the argument is invalid..
assume premise1, premise2, premise3, are true..and conclusion is also valid
premise3: is true
premise2: can be true..if 'B' is true..
premise1:can be true if 'A' is true.
and in given conclusion: not A is true..
so here A and not A...both are true..so its a CONTRADICTION....and hence..ARGUMENT IS INVALID.