87Mapping as a mode of governance, as considered in the previous two chapters, has an ontology of processual emergence and depth. In contrast, Sensing works on the surface, on the ‘actualist’ notion that ‘only the actual is real’. 1 As Roy Bhaskar, the originator of the philosophy of critical realism, has argued, ‘actualism’ can be seen to be problematic in that hierarchies of structures and assemblages disappear and the scientific search for ‘essences’ under the appearance of things loses its value. 2 However, if it is understood that causal laws are so mediated by non-linear assemblages, each with their own contingent relations and processes, all the way down, then it would make sense to think less about ‘drilling down’ in ever more technically exhaustive ways and, instead, to think more about engaging with surface appearances. Once causality appears to have lost its ‘modernist’ linearity, the question of causation increasingly appears to be more a matter of metaphysics than one of relevance for governance, which needs to be much more pragmatic in relation to problems and concerns.