B.5.QD.CF:4.2 - Recover the inference and the status of its premises

Work backward from the conflict to the statements that produce it. Use B.5.RA if the argument needs reconstruction. Keep their different roles understandable: what the work requests, what was observed, what the model assumes, and which proposed operation is supposed to supply a result.

Pay attention to necessity. “To obtain A, D is necessary” means A implies D. “Doing D under conditions K obtains A” is a sufficiency claim. Success with D alone supplies no argument that every way of obtaining A requires D. The question may be whether another operation E obtains A while avoiding the condition that obstructs the other requirement.

A small set of jointly conflicting statements is often sufficient. For a finite constraint account, one can hold the requirements fixed and examine what happens when one assumption is omitted. A remaining solution identifies a candidate assumption to examine; it does not establish that the assumption is false or dispensable in the intended work.

Find a minimal conflicting set only when the smaller explanation changes the task. “Subset-minimal” means that removing any member of that set removes its inconsistency. It does not mean that the set is the smallest possible, that repairing it is cheapest, or that no other conflict remains outside it.