The return of potencies in evolutionary biology: towards an ontology of what is possibleWhereas the Modern Synthesis view of evolution has been grounded on the theoretical pillars of molecular chance and historical contingency, the randomness of evolutionary change has been challenged from a phenomenological and an explanatory perspective. The investigation of the tempo and mode of evolution has entailed an increasing interest in the directionality of evolutionary change and the logics of morphospace. From a causal perspective, evodevo has brought to evolutionary biology many dispositional terms that highlight the ‘inherency’ (vs. the Darwinian contingency) of evolution. In this paper, I explore how the introduction of dispositions into the causal structure of evolutionary biology has lead evo-devo practitioners to confront the ontology of chance and contingency underlying the inherited view of evolution, and begin to articulate a dispositional theory of evolutionary change. Firstly, I analyze how the dialectics between the actual and the possible underlies many theoretical tensions between the population and developmental approaches to evolution. In this context, I distinguish two notions of the possible associated to different epistemological goals in evo-devo: the morphologically possible (variability) and the functionally possible (evolvability). Secondly, I explore how the introduction of the possible transforms the relationship between chance, determinism and contingency in evolutionary theory