 The first is a claim that in brain bisection patients, there is no whole number of persons. So far, we have talked as though in brain bisection we always end up with some clear number of instances of unified consciousness. Nagel (1971), one of the early philosophers to write about these cases, rejects that view. For him, there is no whole number of ‘centres of consciousness’ in brain bisection patients: there is too much unity (for example in life outside the laboratory and even in behaviour within) to say “two”, yet too much separation in the specially contrived laboratory situations to say “one”. 