That's silly, of course it can be taught, and it can even be measured if that's so important to you. Can this person read a text and understand the arguments that are being made? Can this person tease out subtexts and narratives and ideologies in the world around them? Can they write and make themselves understood? Can they follow an argument to its logical conclusions or pick apart failures in an argument? Can they recognize aesthetic and technical choices, or stylistic and intellectual affinities within a work of art? These are all skills necessary to be engaged in civic and cultural life, and they can absolutely be taught.