BillD, it does help to connect LOGIC to Math. Maybe Carol can understand this--if "A" is true, and "B" is true, then a conclusion--"C" is true. If either A or B is false, then C must also be false, because of false premises. We must start from valid data if we are to have valid conclusions. Carol, Rules of Logic ARE, just like gravity IS,or as Bill says, 2 + 3 ALWAYS equals 5, at least in THIS Universe. Logic is not Common Sense, nor is it Folk Wisdom. Logic is a special kind of math which uses words instead of numbers.