Can Harsanyi’s Theorem Defuse Sidgwick’s Dualism?

This paper articulates an objection to Henry Sidgwick’s dualist account of practical reason. Sidgwick claims that if egoism and utilitarianism offer conflicting advice, only “non-rational impulses” can guide our choices. In response, I demonstrate that Harsanyi’s Aggregation Theorem can be applied to conflicts between egoism and utilitarianism. By generalizing the theorem and weakening one of its premises, the recommendations of egoism and utilitarianism can be combined into a weighted sum, without the need to invoke non-rational impulses.