The study of chance sets some problems to the epistemology of sociological action theories. As a matter of fact the purpose of an action would remain ambiguous to an occasional observer when depending on the irruption of chance, by these cases Aristotle adopts a position that identifies the point of view of the actor to the one of the observer. At the same time theories about olistic models of action embrace this position: the acceptation of a systemic intentionality would give access to an epistemology recognizing chance, its unforeseenable irruption, by an objectivistic perspective. If for Aristotle chance imposes itself from the epistemological point of view as a third explanans to explain those events that don't happen neither by necessity nor by contingency, nowadays in social systemic perspectives the concept of risk may be assumed as a middle term that make possible to mediate between contingency and chance. That is, the happening of chance is not seen anymore as composition of independent acts among lonely actors, but as somewhat that happens in a public relational space meant for the free exchange among indivduals and at the same time it works in order to regulate the possible relations between the individuals themselves
