Editing Indeterminism (section)

==Necessary but insufficient causation==

{{further|Necessary and sufficient conditions}}
Indeterminists do not have to deny that causes exist. Instead, they  can maintain that the only causes that exist are of a type that do not constrain the future to a single course; for instance, they can maintain that only necessary and not sufficient causes exist. The necessary/sufficient distinction works as follows:

If ''x'' is a necessary cause of ''y''; then the presence of ''y''  implies that ''x'' definitely preceded it.  The presence of ''x'', however, does not imply that ''y'' will occur.

If ''x'' is a sufficient cause of ''y'', then the presence of ''y'' implies that ''x'' may have preceded it. (However, another cause ''z'' may alternatively cause ''y''. Thus the presence of ''y'' does not imply the presence of ''x'', or ''z'', or any other suspect.)

It is possible for everything to have a [[necessary cause]], even while indeterminism holds and the future is open, because a necessary condition does not lead to a single inevitable effect. Indeterministic (or probabilistic) causation is a proposed possibility, such that "everything has a cause" is not a clear statement of indeterminism.