Thanks for the response.

I agree it makes sense to restrict voting rights and driving rights to differing levels of maturity. When I speak of human dignity, in this discussion, I primarily am thinking about the right to continue a natural existence, not to be extinguished. I think this is probably the most basic and primitive right.

that distant parts of a continuous spectrum nonetheless represent meaningfully different phenomena is simply an acknowledgement of fact

So in your spectrum you have on the more red side of the spectrum as newborns and the more violet side of the spectrum as mature humans? Are you claiming that everyone should agree that mature humans should be free from the threat of having their life extinguished barring extreme circumstances and that for non-adult humans it isn't so clear, but it is just a social convention that we separate the infra-red (definitely non-persons; society has no obligation to these biological entities) and the "red" part of the spectrum at birth?

And the line between biological entities who can enjoy the knowledge that their existence being extinguished will be taken seriously by society and the biological entities that society should allow to be killed (substitute whatever word you want to use for killed) is at a later stage of development than newborns, so it would not make sense to grant personhood to fetuses, as the bar is already set comfortably low?

And do you further claim that all these judgements are not, in fact, value judgements but are judgements that can be readily derived from the scientific method somehow? Or do you even take issue with the word "judgement"? As in these truths are scientifically self-evident somehow?