ABSTRACT
Descartes believed that one can discover metaphysical truths by applying a particular method. The method was simply to begin by calling into question the truth of everything that can be doubted. That which one cannot doubt must be certain, and upon these certainties all other metaphysical and scientific truths can be founded. In this century the sense-data theorists best exemplify this type of Cartesianism. They believed that indubitable knowledge of certain non-propositional items, sense-data, is the basis for all propositional knowledge about the world. Now Brian O'Shaughnessy, who claims that one has quasi-incorrigible knowledge of one's trying, is employing a similar Cartesian method. If one focuses on cases of action in which the agent is the subject of gross illusion or deception in regard to acting, then what will remain unquestionable is that the agent tried. Such a method supposedly will reveal the essence of action as this quasi-incorrigible event of trying, akin to what philosophers have traditionally called a 'volition' or 'willing.' O'Shaughnessy's strategy is thus to employ a kind of Cartesianism to establish volitionism.
