‘When we see, hear, smell, taste, feel, meditate, or will anything, we know that we do so. … Consciousness … is inseparable from thinking, and essential to it. …’John Locke, Essay Concerning Human Understanding ‘Psycho-analysis … cannot accept the identity of the conscious and the mental. It defines what is mental as processes such as feeling, thinking and … willing. … ’Sigmund Freud, Introductory Lectures on Psycho-analysis.In this paper I shall provide a novel version of a traditional epistemic criterion for (...) distinguishing mental entities from nonmental ones, and defend it from likely sorts of objections. By the phrase ‘criterion of the mental’ I mean a set of conditions which is necessary and sufficient for an entity's being mental. (shrink)