Explanation : Whether it is valid or invalid is the
characteristic feature of all arguments
which is tested by determining its truth
or falsity on the basis of the Fundamental
Principle of Argumentation. The principle
says:
An argument is INVALID if and only if
it is logically possible for the conclusion
to be false even though every premise is
assumed to be true.
Testing the validity of an argument is a
three-step process:
(i) Each premise as well as the
conclusion is symbolized.
(ii) A truth table with a column for
each premise and a column for the
conclusion is prepared.
(iii) If the truth table has a row where the
conclusion column is FALSE while
every row in the premise column
is TRUE, then the argument is
INVALID. Otherwise, the argument
is VALID.