The trouble is people begin a the rejection of universality and difference in the first instance. Both become lost in an attempt to define each other in the basis of the other.
Are we humans? Well, that universal (or rather similarity) is thought to be given by difference-- have the arms, the legs, the DNA, etc.,etc. and one is human. Lack them and one is not. Yet, this narrative always bashes up against are usage and values. We claim the genocidal manic is not human. We pronounce the entity with experiences and intelligence like us belong to humanity. The difference we thought defined the universal of human doesn't so at all-- turns out we may human robots and inhuman
homo sapiens.
A similar mistake is made with difference. How do people usually think difference is defined? By a universal of some sort. Humans are not animals because they
always have this particular sort of brain with intelligence. To understand and spot difference, it is thought we pick out a universal form an then note the different states of the world it constrains. Yet, this is never satisfactory because we find it is
different beings who are similar.
Supposedly, the universal (Willow) defines the difference (to be tortured Willow and tortured Willow) and is needed for me to care about a difference (tortured Willow), but we can see this doesn't make sense, for the two Willows are different. My to be tortured self will never experience torture. By difference it has no torture to fear.
The fear only make sense when tortured Willow matters. Concern not for the universal, but for
difference. When tortured Willow matters, it's to different Willows that proceed them. I do not fear my present self, but for the person who comes after me. Identity over time is not a universal that constrains the world, but
difference expressing some sort of link or similarity-- the body, actions and experiences of the to be tortured person are linked to the difference of tortured person.
Over time, I am many different people who's actions affect those to come, who follow from my present body and experiences. If I care which person exists in the future, I have to be careful about what's happening in the present. To be condemned to torture means that, barring some cultural change, pardon or incompetent guards, a future person linked to my body an experiences will experience torture. If I want to avoid that fate for the person who comes after me, my fear makes perfect sense.
The "problem of universals and continuity" is an illusion generated by not accepting difference and universality for themselves.