Thomas Nagel, in “Brain Bisection and the unity of conscious”, presents a thesis on the non-existence of the self in human beings. Selves, in the case of Nagel's argument, are the physiological bases of the mind that constitute the subject of experience. The self can be seen as the fundamental person, or “personal identity.” It has been very difficult to identify the number of people present in a human being, and the initial and seemingly apparent answer "one" becomes less convincing upon examination of other evidence. (Nagel, 1971, p. 396) In particular, medical patients who have undergone partial or full body callosotomy exhibit strange behavior under specific conditions that cast doubt on the conclusion that every human has a self. The corpus callosum, the cerebral commissure between the two hemispheres of the brain, serves as a communication pathway for messages between the hemispheres. Typically, information from the sense organs is duplicated or communicated throughout the brain, regardless of where a sensation originates and which hemisphere it is directly connected to via the corpus callosum. (Nagel, 1971, pp. 396-400; Sperry, 1968, pp. 723-725; Sperry, 1984, pp. 661-663) When the corpus callosum is severed, it is often a last-ditch surgical procedure. remedy to solve a medical problem such as epilepsy, not all information can be transmitted between disconnected hemispheres, and the resulting effects provide interesting evidence that has given rise to many theories regarding the self and its countability . These effects have been demonstrated in monkeys, humans and cats using carefully designed studies and experiments. For human patients, a special device is used to stimulate each hemisphere separately....... middle of paper ......sphere dominance to understand the intentions of others: Evidence from a split-brain patient . BMJ Case Reports [doi:10.1136/bcr.07.2008.0593].Puccetti, R. (1973), “Brain Bisection and Personal Identity”, British Journal for thePhilosophy of Science 24, 339-55.Puccetti, R. ( 1989). Two brains, two minds? Wigan's theory of mental duality. The British Journal for the Philosophy of Science, 40: 137-144. Sperry, R. (1968). Hemispheric disconnection and unity in consciousness. American Psychologist, 23, 723-733. Sperry, R. (1984). Consciousness, personal identity, and the split brain. Neuropsychology. 22, 661-673. Vining, E., Freeman, J., Pillas, D., Uematsu, S., Carson, B., Brandt, J., Boatman, D., Pulsifier, M., Zuckerberg, A. (1997). Why would you want to remove half a brain? The outcome of 58 children after hemispherectomy. Pediatrics, 100, pp. 163-171.