 Ryle’s express target in The Concept of Mind was the Cartesianism of the Official Doctrine, and the ontological, epistemological and semantic predicament we would be confronted with if the view were correct. Because of this target, many of his reminders about how mental expressions are used point to the kinds of circumstances and performances that would satisfy them: often these include what others suitably trained have no trouble seeing. But he was dissatisfied that in this work he left out some of the cardinal uses of concepts of thinking, in which there may be no performances for others to witness. Certainly, the concept of thinking applies to observable performances. But it also applies to the many thinking-activities we may imagine of Rodin’s Le Penseur who is merely sitting on a rock with his chin in his hand. Ryle’s professed long-range objective in much of his later work was to come to an understanding of the various sorts of thinking qua pensive without committing either the “Category-howler of Behaviourism or the Category-howler of Cartesianism” (1979a, 17). In these later articles, he suggests that what is needed besides the choice between “not muscular, therefore inner” or “not inner, therefore muscular” is a way of enlarging the domain of the mental so that it includes not only actions or performances but also certain omissions or failures to act that are conceived on a relatively high step of the ladder of sophistication of mental discourse (1979c, 119).