Mill’s claim that the value of freedom of expression lies in keeping true beliefs from becoming dogmatic reflects his view that freedoms of thought and discussion are necessary for fulfilling our natures as progressive beings (OL II 20). For instance, Mill appeals to a familiar distinction between true belief, on the one hand, and knowledge, understood as something like justified true belief, on the other hand (II 22; cf. Scanlon 1972; Ten 1980: 126–28). Progressive beings seek knowledge or just