Preference Utilitarianism by Way of Preference Change?

This paper revisits Richard Hare's classical and much discussed argument for preference utilitarianism (Moral Thinking, 1981), which relies on the conception of moral deliberation as a process of thought experimentation, with concomitant preference change. The paper focuses on an apparent gap in Hare's reasoning, the so-called No-Conflict Problem. A solution to this difficulty which was proposed in (Rabinowicz and Strömberg 1996) is re-examined and shown to lead to a number of difficulties. The paper therefore also considers an alternative idea, due to Daniel Elstein. This new proposal may well turn out to be the best way of filling the gap in Hare's argument.
The paper also examines whether the gap is there to begin with: The problem should perhaps be dissolved rather than solved. This suggestion goes back to an idea of Zeno Vendler (1988). Unfortunately, it turns out that Vendler's move does not save Hare from criticism: It does dissolve the No-Conflict Problem, but at the same time it gives rise to another, potentially more serious difficulty.