To prove a conclusion, an argument must have two essential
First, its premises must be true. An argument is a method of
establishing the truth of a proposition by relating it to facts
we already know. So we have to start from facts; false premises
don't prove anything.
Second, the premises must be logically related to the conclusion
in such a way that if the premises are true, the conclusion is
likely to be true as well.
We refer to this second attribute--the capacity of
the premises to support the conclusion--as the logical strength
of the argument.