Contrary to received opinion among philosophers, psychologists, and neuroscientists, conscious duality as a principle of brain organization is neither incoherent nor demonstrably false. The present paper begins by reviewing the history of the theory and its anatomical basis and defending it against the claim that it rests upon an arbitrary decision as to what constitutes the biological substratum of mind or person.

Many philosophers say that two or more people or thinking beings could share a single human being in a split‐personality case, if only the personalities were sufficiently independent and individually well integrated. I argue that this view is incompatible with our being material things, and conclude that there could never be two or more people in a split‐personality case. This refutes the view, almost universally held, that facts about mental unity and disunity determine how many people there are. I suggest (...) that the number of human people is simply the number of appropriately endowed human animals. (shrink)