> It's continuation of consciousness instead of consciousness.
It has to be. We need some interval of time to experience anything. Continuity also relates a lot to agency. Most people want to keep experiencing over dying.
> Consciousness throughout life takes many forms. A newborn, an adult, someone with dementia, people with various other types of mental illnesses. It makes it hard to define consciousness.
Consciousness is a very low bar honestly. Every one of the people mentioned would possess it in some form or another. You could use a different term if this one is too fuzzy.
> The fact that continuation of consciousness cannot stand by itself, it needs the other factor: humanity.
I think this is more a reflection of our current world than some perfectly ethical one. Since we’re humans, we’re always going to value our own offspring more than a dog. That’s deeply instinctual stuff. That doesn’t mean dogs aren’t richly conscious animals deserving of significant ethical consideration, but we’re not unbiased neutral observers in the matter. I’m just trying to come up with a consistent ethical approach to a narrow issue; for situations where two conscious things are being compared, you might be able to denote specific capacities, like recognition of self, by which you prioritize e.g. a person over a dog, but this is all very hypothetical and I don’t think we need it for the abortion debate.
> A sperm isn't a young human; it isn't growing into an adult human. An egg isn't a young human; it isn't growing into an adult human.
But they are? The only reason they try to fuse together at all is in service of the growth of a human.
> 96% of biologists say human life beings at fertilization. Not when the sperm and egg are nearby each other.
They’re not talking about personhood or something. They’re talking about something fundamentally classificatory, like asking “what makes a species separate from other species.” The usual answer is that they can’t breed with each other, but there are lots of kinda fuzzy exceptions and gray areas with that. To word it better, if I said “Presume the goal is to determine when, in the study of individual organisms, such organisms can be thought to come about. Tell me what stage in the development of a human comes first,” the answer would need to be around the time of fertilization because the question presumes the frame of biological study, the existence of an initial stage, etc.
> If the 3 independent beings were sitting in a room, would we call them 1 merged being? No. They're still 3 independent beings. Same with the sperm and the egg. Just because they're nearby each other doesn't make them a human life.
Right. By the same token, I don’t think a single cell constitutes a “human life”, with all the connotations that phrase carries. If it’s most appropriate to call that single cell a human life, then clearly human life isn’t the thing that determines ethical consideration. My fixation on the sperm + egg -> zygote transformation is a consequence of your belief that the left term isn’t morally significant but the right term is. I think everything that we care about is the same for both terms. Non-conscious, relatively simple mechanically compared to an adult, no nerves or brain, no awareness of the world, no hopes or dreams. The zygote lacks everything essential to personhood at this stage other than its human origin, which it shares with the sperm and egg.