B.5.TC:5.3 - Agreement in observation, disagreement under intervention

An indicator X and an output Y always follow a binary controller command U. Two causal hypotheses explain the observed pairs: A uses X := U and Y := X; B uses X := U and Y := U. In A, the indicator drives the output. In B, the controller drives both directly. Both yield X = Y = U in ordinary operation.

The question is now what happens when X is forced to 1 while U remains 0. Represent this intervention by replacing the assignment to X. A gives Y = 1; B gives Y = 0. The same observed pairs leave that difference unresolved.

The next contribution could be the circuit description, an already available intervention result or a worthwhile discriminating test. If the work only predicts the observed indicator from U in unchanged operation, this causal difference need not be settled for that use. If it proposes controlling Y through X, retain the unresolved consequence until the needed causal premise is supplied. C.28 governs that intervention claim.