 Retributivism seems to contain both a deontological and a consequentialist element. Its negative desert element is deontological. It is a conceptual, not a deontological, point that one cannot punish another whom one believes to be innocent  (section 2.1).  But it is a deontological point that an avenue of justification for hard treatment is opened up, making permissible what might otherwise have been impermissible, if that person is guilty and therefore forfeits her right not to be so treated.