Quote Originally Posted by Burney View Post
No, I'm sorry, but the significant difference here is of potential. The PVS victim has reached a point where life in terms of their brain activity has to all intents and purposes ceased and they can only be sustained artificially. They have no potential for improvement and are alive in name only. When you turn off the machine, nature takes its course.
An embryo, by contrast, is full of potential and to end it is to snuff all of that potential out by a deliberate act of killing. The two are qualitatively different in both ethical and medical terms. One is entirely justifiable in moral terms, while the other is highly morally dubious.
You seem to think that I'm arguing from a position whereby all human life is innately sacrosanct. I'm explicitly not arguing that. I'm arguing that we should acknowledge first of all that we're ending a human life and then work from there.
In which case the embryo is only a 'potential human life' as you there is no certainty as to how it will develop.

The complexity of your reply sort of proves my point, Burney. There are so many angles to the 'human life' definition and debate that I fail to see how anyone can come up with anything definitive. And if you can't reach an agreement as to what is or is not 'human life' I also fail to see how it can be used in the argument.

The alternative is to simply be practical and not bother with nebulous definitions.