In probabilistics, reasoning at optimum entropy (ME-reasoning) has proved to be a most sound and consistent method for inference. This paper investigates its properties in the framework of nonmonotonic reasoning. In particular, we show that ME-reasoning satis es cumulativity and loop, and we focus on its connection to conditionals. Finally, we introduce the notion of a universal inference operationto generalize nonmonotonic reasoning, thus providing a frame more appropriate for linking nonmonotonic reasoning with belief revision.