I stumbled onto this while looking for something completely different (the book by Michael Gazzaniga), and found it interesting enough to share.<p>I was intrigued by the idea in these paragraphs about three different kinds of knowledge: of the world, of one's mind, and of other minds.<p>> There are three broad domains of knowledge that, taken together, seem to exhaust what it is that we can know or conceive of knowing. The first is the simplest to describe—it is knowledge of the nonsocial environment, the world we share with others. The common-sense view is that this domain of knowledge is shared, public, and hence objective in that sense. How we come to acquire this knowledge is also no mystery—through our senses and perception of the world (although the acquisition of such knowledge already depends on learning, selection, and categorization mechanisms that are in part innate). Although the kinds of inferences that we make about the world are certainly complex, it seems that much of this domain of knowledge is shared with other animals. Like us, mice, cats, dogs, and monkeys know about objects in the world, the properties they possess, and the events they transact; they know something about which objects are good and which are bad, and they direct their behavior accordingly.<p>> The second and third domains of knowledge are more mysterious, and it is unclear to what extent, if at all, other animals have access to them. These are knowledge of other minds, and knowledge of our own mind. Although many biologists who study social behavior in animals treat their processing of social information as an issue in perception that is just a special instance of the first category discussed above, some, especially those working with primates, focus on knowledge of one's own and others' minds. Workhorse tasks have been devised to assess the abilities in question: deception as a test for knowledge of other minds, and mirror self-recognition as a test for self-knowledge.