@PeterCH: I will get back to the rest at a later time (out right now), i promise.
Skip to the clutch point for now:
Is one a person because of biology or because of sentience(the iRobot/'The Island'/bottle-nose dolphins paradox)?
I understand that the robots in iRobot (and all science fiction) AI are all fictional. Do we have a way to know how they would react if they were real?
Bottle nose dolphins. What about dogs? Dolphins are not human. They also can't reason as us. They are intelligent but don't approach humans.
First of all humans are biological. We are alive. As are dolphins and dogs. Robots are not. They could give the appearance of being alive or they could be programmed to give human like emotional responses, perhaps even reason. Suffice to say if we could produce such AI, we could mass manufacture it. We would then create identical AI units. We could if necessary turn them ON or OFF at will and control them.
When it comes to people, each person is unique. They are formed by their DNA and also by their environment - they are loved, taught, exposed to various behaviors. They are also like us - they are us. Robots are artificial - machines - they can be mass produced, identical, shaped in any way we want by changing their programming - one can't readily do that with a human - we humans inherently are individualistic and we have compassion, empathy, sympathy - these feelings are genuine and aren't designed for show or tailored with the change of the lines of code. We also are programmed to love and take care of other people - children, parents, relatives, friends, people who do good, people we admire, who we respect etc.
Dolphins- well they're not as smart as us, they cannot really love us, they can't really act selflessly (even though they sometimes help people). We don't understand them fully - as we can't communicate with them and their abstract abilities, appearance, habitat, values etc are different to ours. Heard of a dolphin which loves poetry or philosophy?
Why should we care when something develops human DNA, if we are to terminate it (as a full entity) before it becomes sentient?
I think we should care because 1. It is new human life. We should respect and value ourselves and put ourselves above everything else - above money, politics, science (or hunger for research budgets). We should have that fundamental belief that killing all human life is wrong - we should have no wars, therefore, do death penalties etc - as far as possible. 2. Slippery slope. Yes right now one can say that if we have centralised cloning and research it will all be under the thumb of the regulators but how far can we push the envelope? If the embryo is a new person but not worthy of support, why should a less productive but definately human adult person be supported? To me this slippery slope is dangerous. It boils down to principles.
Why should the 'fusing' really matter, if we are to decide that it won't be sentient? We certainly can't kill something(the sentience in the being as a whole) that has never or will never, planned or not, exist.
Because it's a new individual. We are playing with ourselves. And I don't have an issue with God here - He may even not mind - who knows - I have an issue that we are deciding who lives or dies. My empathy sensor does not like it. I don't think we should automate or industrialise humanity to such a point. Arguably many people say this is wrong too with medicine. We've thrown the Hippocratic Oath away for money and big pharma. Do you not agree that this is similar too?
Could we kill something (the sentient in the being as a whole), that we plan not to exist in the first place?
Yeah but we are exercising control over who is and who isn't? Aren't we?
Who, really is to say that it 'has to exist' if it is not even exist to itself?
This can be extrapolated to people with brain damage, young infants and the elderly or the demented. Also it's about us. This is a new HUMAN BEING and he we just use it for spare parts. It's strict I agree but to avoid just pushing the envelope further.
When we decide who lives or dies, even at an early stage and we create new individuals to harvest them for spare parts we are dehumanising ourselves and what it means to be human. At the end defining humans on higher attributes such as 'sentience' can lead to subjective changes to what it means to be a human. Some would say that the more primitive or less intelligent are not really human. What about concrete thinkers? Are they really human? Less intelligent people? Less educated people? People with particular circumstances?