  And here is yet another way of looking at the matter. Suppose we  agree with Parfit and others that identity just is not what matters  for, among other things, defining and delimiting the scope of  egoistic concern; suppose instead it is Relation R. FDS, because of  her loss of memory and the like, will bear a very limited degree of  that relation to EAS. EAS will thus be strongly R-related with most  of the previous stages of her life (the chains of connectedness, let  us stipulate, are very strong), but very weakly R-related with FDS,  even though, it seems clear, FDS remains a stage of her life. But the part of her life most deeply prudentially unified – the far  larger, more dominant part of her life – is the part of which  EAS was still a strongly R-related part. Thus it might be that the  wishes of EAS to preserve a coherently meaningful and valuable life  ought to control here, given that the longer FDS lives, the worse she might retrospectively render EAS's life. That is, what is good for  the deepest, longest prudential unity will be closest to what is best for the life as a whole, so FDS's good ought to be sacrificed for the sake of the good of the whole, as articulated by EAS in her advanced  directive (see McMahan 2002, 502 for an argument like this).