The Problems of Philosophy advances an epistemological theory and a discussion of truth. Bertrand Russell uses an analytic method to make distinctions concerning our judgments about reality. He employs Cartesian radical doubt in the beginning as he concentrates on our knowledge of the physical world. Claiming certain beliefs about the table in his room, he wants to know if he really has any kind of knowledge through his beliefs and, if so, what kind of thing is the table. He reasons that the table consists of matter and that there is a method by which he can have knowledge of it. Seeing the table involves an awareness of something, a patch of brown that is oval. He calls this something a "sense-datum." It is not the sensation, but what the sensation is of. We take the sense-data to be signs of the existence of physical objects. From the experience of sense-data, we practice a rational process of inference to get to the physical world.