In retrocausation different causal events can produce different successor events, yet a successor event reflecting a particular cause occurs before the causal event does. It is sometimes proposed that the successor event is determined by propagation of the causal effect backwards in time via the dynamical equations governing the events. However, because dynamical equations are time reversible, the evolution of the system is not subject to change. Therefore, the backward propagation hypothesis implies that what may have seemed to be an arbitrary selection of a causal factor was in reality predetermined.Yet quantum randomness can be used to determine the causal factor, and a quantum random event is ordinarily thought of as being arbitrarily generated. So we must ask, when quantum random events occur, are they arbitrary (subject to their probabilistic constraints) or are they predetermined?Because psychokinesis (PK) can act on quantum random events, it can be used as a probe to explore questions such as the ...