Margaret Morrison (Toronto) gives a talk at the MCMP conference "Reduction and Emergence in the Sciences" (14-16 November, 2013) titled "The Physics of Ontological Emergence". Abstract: Emergent phenomena are typically described as those that cannot be reduced, explained nor predicted from their microphysical base. However, this characterization can be fully satisfied on purely epistemological grounds, leaving open the possibility that emergence may simply point to a gap in our knowledge of these phenomena. By contrast, Anderson’s (1972) claim that the whole in not only greater than but very “different from” its parts implies a strong ontological dimension to emergence, one that requires us to explain how macro properties characteristic of emergence can be ontologically distinct from the micro properties from which they emerge. This is partly explained by using RG methods to show how the ‘universal’ characteristics of emergent phenomena are insensitive to the Hamiltonian(s) governing the microphysics. But this is not wholly sufficient since it is possible to claim that the independence simply reflects the fact that different ‘levels’ are appropriate when explaining physical behavior, e.g. we needn’t appeal to micro properties in explaining the macro behavior of fluids. The paper attempts a resolution to the problem of ontological independence by showing how a closer examination of RG methods can provide a way of explicating the relation between micro and macro properties, a relation that satisfies the requirements for ontological emergence in physics.