 With respect to Spekkens’ more general understanding of contextuality, recall that it is an explicit assumption of the ontological models framework that the ontic state is independent of the measurement procedure. Thus, hypothesizing retrocausality is an unequivocal rejection of the ontological models framework. But one might wonder whether Spekkens’ principle of parsimony might be recast to apply more generally to retrocausal models.  §7.3  considers a result due to Shrapnel and Costa (2018) that indicates that retrocausal accounts must indeed accept Spekkens-type contextuality.