ABSTRACT
The problem of having higher-level properties exercising causal influence on lower-level properties, the so-called downward causation, is one of the thorniest issue for those who want to defend the very idea of emergence. The appeal to downward causation is needed to avoid a host of difficulties. The concept of emergence has been invoked to give higher-level properties a causal status that is, placing them in the causal order. This is an ultimate consequence of Marc Bedau's first point, the fact that emergent properties are constituted by underlying processes. Ned Hall has isolated two different conceptions of causation, a productive and a conceptual one. Emergence, on the one side, pulls in the direction of making properties at one level autonomous with respect to properties belonging to a different level; downward causation, on the other side, points out that the causal efficacy of properties cuts across and holds between levels, so that levels are the tie for the efficacy of emergent properties.
