 is a good or “valid” argument, it is not formally valid.  On the Demarcater’s view, logicians who investigate the (non-formal) kind of “validity” possessed by \(\refp{chicago-north}\) are straying from the proper province of logic into some neighboring domain (here, geography or lexicography; in other cases, mathematics or metaphysics). For the Demarcater, then, understanding the distinction between logical and nonlogical constants is essential for understanding what logic is about. (For a forceful statement of the Demarcater’s point of view, see Kneale 1956.)