If you ask two people, do these two people necessarily tell you the same correspondence between descriptions of matter and person-parts? You keep using that word "objective," I do not think it means what you think it means :P
Sorry to be such a downer, but as a human my definition of anything complicated is imprecise and pretty inconsistent - if you ask me two different ways I can give you two different answers. I honestly do not know any particularly good ways to get definitions out of humans.
I guess one way is to stick to simple things - the "looking under the lamppost" approach. For example, the "computational me" who thinks some exact thought that I'm thinking is a better-defined idea than most. But on account of its simplicity it misses a lot of nuance in the human idea of "me," and so it's not actually very useful.
Nonetheless it's important to attend to these "better-defined" parts of you, because that's where we start to get away from the big distraction created by the freedom to self-define. This flexibility in the notion of self is mostly about what you get to include and exclude. So there's a large collection of "potential self-parts", but the potential self-parts themselves don't exist just by definition; they are the actually existing raw material in terms of which a definition of self gets its meaning - these are a part of me, those are no...
http://www.scottaaronson.com/blog/?p=1103
Eliezer's gung-ho attitude about the realism of the Many Worlds Interpretation always rubbed me the wrong way, especially in the podcast between both him and Scott (around 8:43 in http://bloggingheads.tv/videos/2220). I've seen a similar sentiment expressed before about the MWI sequences. And I say that still believing it to be the most seemingly correct of the available interpretations.
I feel Scott's post does an excellent job grounding it as a possibly correct, and in-principle falsifiable interpretation.