Many themes of late twentieth century ethics are prefigured in Sidgwick’s Method of
Ethics. In particular, Sidgwick’s ‘Dualism of Practical Reason’ sets the scene for current
debates over the demands of morality. Many philosophers agree that Sidgwick uncovers
a deep and troubling conflict at the heart of utilitarian ethics. But Sidgwick’s own response
to that conflict is treated, not as a live philosophical option, but as a historical
oddity. In the twenty-first century, few philosophers see the intimate connection between
the dualism of practical reason and the investigation of psychic phenomena that
played such a large role in Sidgwick’s life. The aim of this paper is to investigate Sidgwick’s
own approach to the dualism of practical reason. Its general conclusion is that a
non-dualistic morality demands less than a theistic religion, contrary to what Sidgwick
worried - especially as concerns personal immortality and freedom.
