Board Thread:Questions and Answers/@comment-4495539-20140531082603/@comment-24152851-20140919002808

True. Though of course they're not gonna be exactly the same.

The same can be said for Paradox and the Doctor. Paradox can't regenerate his dismembered hand, and is immortal due to existing outside of time. The Doctor can regenerate his hand, and his immortality is because he repairs any damage done, but it's possible to kill him since he exists in the Universe. Also I believe there's that trivia of Paradox believing in magic (although I don't agree with that since the Doctor believed in magic in the Shakespeare episode).