MMP.15:10 - Architectural Rationale

Mechanism replacement gives intervention semantics within a model. Identification adds a different construction: showing that the needed intervention consequence is common to the causal models compatible with available laws and assumptions, or exposing where it is not.

The target-first construction avoids demanding a complete causal model when a mean, contrast or bound suffices. Separating derivation from estimation lets one identifying expression support different appropriate inferential methods. Separating source laws prevents mathematical convenience from turning selected records into information about an unobserved population.