The demand of contingency and its irreducible nature in Aristotle

Here is expounded an interpretation of Aristotle's study of to sumbebekos contained in Metaphysics VI 2-3. This interpretation starts from the examination of the notion of steresis and deals with the modality of contingency named to endekhomenon, trying thus to face up to the statement according to which "it is necessary that there is the kata sumbebekes being" with a view to grasping it not as a doctrine but as something thought in an essential way by a Greek philosopher.