 To what extent we can defend that view will depend on how we understand the relation between the notions of harm as distinguished in  Section 3.1.  Here we will delineate two views of how to understand these notions of harm and investigate the question of the extent to which these two alternative views support Parfit’s “No-Difference View”. According to our first view, one must choose between the “single threshold” and the “single subjunctive-historical” notion of harm: to claim that rights-considerations can guide us in choosing among long-term policies we will have to adopt one of these notions of harm as specifying necessary conditions of harm; in doing so, we have to deny that the other notion specifies necessary (or sufficient) conditions of harm. In other words, the first view considers the “single threshold” and the “single subjunctive-historical” notion of harm as exclusive notions. According to the second view, the threshold notion of harm and the subjunctive-historical notion can be combined.