Tautologies and Illogical Questions
Two related topics occupy this chapter, namely (1) producing a philosophical argument for unerringly determining in writing when to use “whether or not … ” or “whether … ” and (2) appealing to formal logic to certify that a category of questions is inappropriate or illogical. The arguments in favor of (1) derive from Aristotle’s De Interpretatione and from the logical Law of the Excluded Middle. The argument for (2) rests upon logicians’ and grammarians’ appeal to rules of inference that are at home in the canons of formal logic. Taken together, (1) and (2) show the extent to which a knowledge of logic can be invaluable to producing sensible and superior prose.