Ryle states that Descartes made a category error when explaining the relationship between the mind and the body. A category error is best described using an example. The example Ryle uses in the textbook is looking at a university building and asking where the university is. Essentially, a category error is one in which different things belonging to the same category are represented in different categories like buildings and university. The university example is a situation similar to how Descartes describes the mind and body. He describes the mind and body as distinct from each other, while Ryle describes the mind and body as part of each other. Ryle supports his claim by stating the idea of ​​the “dogma of the ghost in the machine.” He describes the ghost in the machine by saying: "Although the human body is an engine, it is not quite an ordinary engine, since some of its workings are governed by another engine within it." (Intro to Philosophy p.369). This means that the mind is a driving force within the body. This is an incorrect statement because the mind is not part of the body because the mind is not tangible and the body is tangible. If the body were to be affected by an observed event, the mind would not be, because to affect the mind one must experience an observed event.