[On Parfit’s view], the boundaries within lives are like the boundaries between lives. So we do not regard people as the morally significant units. This only means that if we are concerned with distribution at all, we shall be concerned with distribution between what are the morally significant units—namely, person-segments or whatever these divisions of a person are. So certainly the fact that a person has suffered more in the past will not make us give extra weight to relieving her suffering now. But if she is suffering more now, we may give extra weight to it. We may be concerned to equalize the distribution of good between person-segments. So all this argument does is remind us that we have changed the units of distribution. It does not suggest that we should be less interested in distribution between them.
John Broome, ‘Utilitarian Metaphysics?’, in Jon Elster and John Roemer (eds.), Interpersonal Comparisons of Well-Being, Cambridge, 1991, p. 94