  Striking a match is a causally sufficient condition of the match’s ignition in a standard sense since, under normal conditions, if one strikes the match, it will ignite. Many other conditions are causally necessary for this event to occur, however—the presence of oxygen, the match’s not being wet, and the like. But in a stronger sense, x is a causally sufficient condition of y if and only if given x alone, y exists or occurs. And in that sense, striking the match is not causally sufficient for the match’s ignition since other conditions are needed as well.