The term “a cause” is an oxymoron. What is not THE CAUSE is NO cause at all. There is only THE cause or NO cause.
Causation requires at least three things, easily remembered by the acronym, SIN
S = sufficiency. The cause produces the effect all by itself. The cause is completely responsible for the effect.
I = immediacy. The cause immediately precedes the effect. Thus, the statement “the gunshot wound to the head instantly killed him and was the cause of death” is closer to the truth than the idiotic statement “smoking causes lung cancer” (20 or more years after taking up the bad habit).
N = necessity. Two senses of necessity. One: nothing but the cause can produce the effect (this is rarely true. In my billiard ball example: the 8 ball cannot be set into motion without some type of an external force, but the external force does not have to the collision with the cue ball). Sense two: The cause necessarily produces the effect, that is, forces the effect to occur, implying that no other event can interfere with the occurrence of the effect once the cause has occurred. A Law of Nature type of connection between the two events.