Full Idea
It is quite uninteresting whether, with half its components replaced, I have the same audio system, and also whether I exist if half of my body were simultaneously replaced.
Gist of Idea
It doesn't matter whether I exist with half my components replaced (any more than an audio system)
Source
Derek Parfit (The Unimportance of Identity [1995], p.302)
Book Reference
'Personal Identity', ed/tr. Martin,R /Barresi,J [Blackwells 2003], p.302
A Reaction
It is impossible to deny this, if the part replaced is not the brain. My doubt about Parfit's thesis is that while I may not care whether some modified thing is still me, my lawyers and the police might be very concerned.