The paper examines one objection to the suggestion that, rather than being subjected to extended prison sentences on the one hand, or simply released on the other, dangerous offenders should be in principle liable to some form of civil detention on completion of their normal sentences. This objection raises the spectre of a, pursuing various reductivist means outside the criminal justice system. The objection also threatens to undermine dualist theories of punishment, theories which combine reductivist and retributivist considerations. The paper (...) attempts to refute the objection by holding that a wedge can be driven between incapacitation and other reductivist measures, and hints at a possibly new version of dualism in the process. (shrink)