Ethical descriptivism is the view that all ethical properties are descriptive properties. Frank Jackson has proposed an argument for this view which begins with the premise that the ethical supervenes on the descriptive, any worlds that differ ethically must differ also descriptively. This paper observes that Jackson's argument has a curious structure, taking a linguistic detour between metaphysical starting and ending points, and raises some worries stemming from this. It then proposes an improved version of the argument, which avoids these (...) worries, and responds to some potential objections to this version of the argument. (shrink)