Threshold dynamics of corrective action in a population model of structural discrimination

Structural discrimination can sustain underrepresentation even when no actor explicitly excludes a group. We develop a simple population model in which current representation changes each type’s per-capita effective rate of maintaining or expanding its presence, while corrective action responds to the gap from a reference-population share. The model yields three main results. First, an exclusionary state can remain stable when corrective action is present but weak relative to representation-dependent structural feedback. Second, the corrective strength required to destabilize exclusion is greater for a focal type that is rarer in the reference population. Third, avoiding complete exclusion is not the same as attaining proportional representation: with finite corrective strength, the stable long-run share can remain below the reference share. These results connect qualitative accounts of cumulative structural disadvantage to explicit conditions for long-run stability. They also suggest that corrective policies should be evaluated by their effective dynamic strength relative to the structural feedback they are intended to change, rather than by their formal presence alone.