 There is also disagreement regarding whether avoidability is a distinct and necessary condition of unjust health inequalities. Sudhir Anand and Fabienne Peter (2000) suggest that unfairness entails avoidability and so is not really separate from it. But avoidability is cleanly separable (in the other direction) from unfairness, and that can be an analytic advantage. For example, it allows the justice of inevitable inequalities in health to be decided without having to engage the issue of fairness at all. Others question whether health differences must be avoidable if they are to count as unjust (Lippert-Rasmussen 2013: 59–60; Wilson 2011: 216). For luck egalitarians, health differences due to natural processes can be unjust regardless of whether they can be prevented or treated. Even if person A has lesser mobility compared to person B due to a genetic condition that is neither preventable nor treatable, the difference between A and B is unjust and A has a claim on society to rectify it, for example, through the provision of a mobility aid or the restructuring of the social environment. Such inequalities are examples of natural injustices—injustices caused by natural processes—rather than social injustices—injustices caused by social processes (Lippert-Rasmussen 2013: 59–60). (For a contrary view, see Wester 2018).