Act individuation: the Cambridge theory
Token action a = token action b iff .... Well, iff what? An agent, P, bends his finger, pulls the trigger, shoots the gun, kills the Queen, and thereby reduces the world's population by one. P did each action on the list by doing its predecessor (if it has one). How many things did the person do? The alternative theories that attempt to answer this question are well known. The most austere theory says that P did only one thing, and that what the list above provides are five different descriptions of one token action. Actions are, on austere theory, movings of the body, variously described.