The following observation arose in the course of a critique of philosopher Derek Parfit.
"Even if the lower-level facts [that make up identity] do not in themselves matter, the higher-level fact may matter. If it does, the lower-level facts will have derived significance. They will matter, not in themselves, but because they constitute the higher level fact."
The quote is from Mark Johnstone, as part of a critique he wrote of Parfit's work on personal identity for a collection called DEREK PARFIT AND HIS CRITICS.
Parfit didn't believe in personal identity. That is, he didn't believe there is any important sense aside from social convention why an "I" of 15 years old is the same person as an "I" of 45, thirty years later, however firmly the latter has memories that might be traced ultimately to the sensory organs of the former.
Parfit can perhaps best be understood as bringing into the Anglo-American analytical philosophical tradition a touch of Buddhism, where of course skepticism about an enduring "I" is familiar stuff. He employed science-fictional thought experiments to this end, such as the one illustrated in the comic whence I stole the above illustration.
Parfit was a “reductionist,” that is, he took the view that what we think are the facts about persons and personal identity can be reduced into more particular facts about brains, bodies, and interrelated mental and physical events. The latter, upon careful inquiry, turn out not to matter all that much, so hat which can be reduced into them doesn't matter either.
That is what Johnstone was critiquing in the quote with which I began. One might say that he offers a coherentist justification for personal identity. It doesn't matter that none of the pieces seem important in themselves. They seem important and thus (given the subject matter) they are important, when seen together.