Share 'The Logical Law of Non-Contradiction?'

Is it the case that proposition "x" must either be "p" or "-P"?   Do you believe this for only SOME propositions?  If so, how can this assertion be a basic law of logic?   Do you believe this for ALL propositions?  If so, wouldn't just one example of a proposition that is both true and false prove the case is only true for SOME propositions?  Thus, if the example is shown, how can the assertion b…