*   reminder: HOW to evaluate arguments using
    propositional logic

    *   identify the *simple* statements (within the premise(s)
        and conclusion) that can sensibly be labeled as TRUE and
	FALSE

    *   Label these simple statements with letters (P, Q, R, ...)

    *   Rewrite the premise(s) and conclusions as statements
        in propositional logic notation

    *   use a truth table to evaluate all the possible outcomes
        for the premise(s) and conclusion

    *   cross out ALL lines in the truth table where ANY
        of the premise(s) is/are false

    *   look at the remaing lines -- is the conclusion false
        in ANY of the remaining lines?
        if it IS, this argument is INVALID (all-true-premises
	do NOT guarantee a TRUE conclusion!)

******
*   ADDING IN another logical operation:
    IF-THEN (also called: conditional, implies)

    P -> Q
    *   read: if P, then Q
        read: P implies Q

    P   Q    P->Q
   --------------
    T   T    T
    T   F    F
    F   T    T
    F   F    T