I would probably say they were dead then and so it would be fine to take them off support and let them die.
I fully agree. This is why I take exception to the idea that it's the
life that matters. To me, it's clearly
something to do with the brain. Heartbeats, muscles, etc. are all distractions. We care about the brain
However, in the case of a fetus, the DNA is ALREADY THERE, and if left alone, it will grow into a child.
I agree that the DNA is already there. And I agree that the fetus will grow into a child. (And we agree that babies are worthy of rights). However, the difference I hold with you is whether the fetus will 'naturally' grow into a baby. It won't grow into a baby all on its own. It needs a wash of nutrients and hormones, in specific combinations, or it will die. IF it's given this wash of nutrients and hormones, it will grow a 'baby brain' that - eventually - will gain a baby's sentience.
But this is the same as the headless body! IF the headless body is given a wash of specific nutrients and hormones, then it will grow a 'baby brain' that - eventually - will gain a baby's sentience.
Importantly,
even if you're responsible for the production of this headless body's state, you're still not responsible to 'regrow' the brain. There's no moral onus to do so. Now, if you chopped off the head yourself, you'd go to jail. Even if you 'regrew the brain' so that there was a newborns brain on the still-living body, you'd still be considered a murderer.
The problem in the debate is that much of the debate is regarding the
essence of humanity. The problem, of course, is that biology has really strong information regarding
essence but we don't instinctively incorporate that information. The 'naturally' doesn't matter, that's a distraction. Whether we do something 'naturally' or artificially doesn't change what our moral onus is after the consequences are realised.