Derek Parfit has argued that egalitarianism is exposed to a levelling down objection because it implies, implausibly, that a change, which consists only in the better-off sinking to the level of the worse-off, is in one respect better, though it is better for nobody. He claims that, in contrast, the prioritarian view that benefits to the worse-off have greater moral weight escapes this objection. This article contends, first, that prioritarianism is equally affected by the levelling down objection as is egalitarianism, but that this objection lacks force. Secondly, prioritarianism is less plausible than egalitarianism because it implies that lowering the level of equality by diffusing a quantity of welfare equally over as many recipients as possible is for the better all things considered, and that the outcome of such welfare diffusion would still be better in one respect, even if the quantity of welfare was radically reduced.