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Recent frameworks describing quantum mechanics in the absence of a globalcausal order admit the existence of causally indefinite processes, where it isimpossible to ascribe causal order for events A and B. These frameworks evenallow for processes that violate the so-called causal inequalities, which areanalogous to Bell's inequalities. However, the physicality of these exoticprocesses is, in the general case, still under debate, bringing into questiontheir foundational relevance. While it is known that causally indefiniteprocesses can be probabilistically realised by means of a quantum circuit,along with an additional conditioning event C, concrete insights into theontological meaning of such implementation schemes have heretofore beenlimited. Here, we show that causally indefinite processes can be realised withschemes where C serves only as a classical flag heralding which causallyindefinite process was realised. We then show that there are processes whereany pure conditioning measurement of C leads to a causally indefinite processfor A and B, thus establishing causal indefiniteness as a basis-independentquantity. Finally, we demonstrate that quantum mechanics allows for phenomenawhere C can deterministically decide whether A comes before B or vice versa,without signalling to either. This is akin to Wheeler's famous delayed-choiceexperiment establishing definite causal order in quantum mechanics asinstrument-\textit{dependent} property.

Quantum chicken-egg dilemmas: Delayed-choice causal order and the reality of causal non-separability