“A [linguistic] theory may be tested by its capacity for dealing with puzzles, and it is a wholesome plan, in thinking about [linguistics], to stock the mind with as many puzzles as possible, since these serve much the same purpose as is served by experiments in physical science.”
— Bertrand Russell, 1905, On denoting, Mind, pp. 484f., with my substitution of “linguistic(s)” for his “logic(al)”