Well, I might as well let the cat out of the bag, since nothing new is forthcoming from pale's 'tripod'. I was sincerely hoping he had something else in mind for personhood.
The standard for personhood in natural law does not come from the legal dictionary -- it comes from
METAPHYSICS. Human existence is known
by its nature, its identity and its distinctness in time and space. While individuals do change in infinitessimal increments from one moment to the next -- the changes being a function of the circumstances they are in, human existence
DOES NOT.
Even if you are not inclined to metaphysical speculation, the standard for personhood -- as seen strictly within the boundaries of natural law -- is
SELF-EVIDENT OR INTUITIVE. There is nothing wrong with such an assertion since
ALL LOGICAL CONCEPTIONS, whether mathematical, ethical or legal need to start from
AXIOMS. They are true assertions that require no formal proof. In fact, no formal proof is possible. That is why first-order logic is deemed axiomatic. And if you are still not convinced, then you might want to check out godel's 1st and 2nd incompleteness theorem.
So, when one concludes personhood as a fundamental part of human existence (no thanks to the legal dictionary), the ambiguities start to disappear.
A distinct (in nature, identity, space and time) human existence starts from conception and ends in death.
A
FUNDAMENTAL AND INDEFEASIBLE right to live is its consequence.
Abortion, capital punishment and euthanasia (in various forms) directly contradict the natural imperative --
THOU SHALT NOT MURDER.