 Supervenience does not fare better, though for different reasons: It seems to be too weak a notion to capture the idea that guided reduction-talk, although it surely is a necessary condition for reduction. In a sense, if mental states merely supervene on physiological states, they exist in a straightforward sense over and above the latter. Such supervenient states are dependent; but being dependent is not enough for reduction (Kim 1998). Note that this is, up to a certain point, a matter of stipulation. However, the stipulation is driven by an intuition: An appropriate definition of the reduction-predicate should adequately mimic the intuitions that guided the use of the term. If, for example, one hope was to formulate a strictly monist position, then relying on supervenience does not serve this goal: Supervenience makes room for a weak form of dualism. For example, it is compatible with emergent property dualism. The emergent properties on such a view are something over and above the physical, but in so far they emerge from the physical base according to natural laws of emergence, they would supervene on that base. Any two cases in which the physical bases were the same would also agree in their emergent properties. Thus supervenience is generally not judged sufficient for reduction. However, many regard it as consistent with reduction or even required. With regard to the mind body case, for example, Kim argues that supervenience is needed for what he calls “minimal physicalism”, whether reductive or not. Under a somewhat liberal though well established interpretation of Nagelian reduction, there is a sense in which reduction is compatible even with emergence, that is: a theory about “novel behavior” (and, thus, emergent behavior) can be deduced from another theory (Butterfield 2011a&amp;b).