 Black is a nefarious neurosurgeon. In performing an operation on Jones to remove a brain tumor, Black inserts a mechanism into Jones’s brain which enables Black to monitor and control Jones’s activities. Jones, meanwhile, knows nothing of this. Black exercises this control through a computer which he has programmed so that, among other things, it monitors Jones’s voting behavior. If Jones shows an inclination to decide to vote for [the Democrat], then the computer, through the mechanism in Jones’s brain, intervenes to assure that he actually decides to vote for [the Republican], and does so vote. But if Jones decides on his own to vote for [the Republican], the computer does nothing but continue to monitor—without affecting—the goings-on in Jones’s head.