To give just one lists of criteria of personhood proposed. Joseph Fletcher a bioethicist proposed the following 15 criteria for being a person:
1. Minimum intelligence: Below IQ 40 individuals might not be persons; below IQ 20 they are definitely not persons.
2. Self-awareness: We note the emergence of self-awareness in babies; and we note when it is gone, for instance, due to brain damage.
3. Self-control: Because a person understands cause and effect, he or she can effectively work toward fulfilling freely-selected goals.
4. A sense of time: Persons can allocate their time toward purposes; non-persons 'live' completely in the present moment, like animals.
5. A sense of futurity: Persons are concerned about their futures; persons lay plans and carry them out; they build their futures.
6. A sense of the past: Persons have memories of their pasts; they can recall facts at will; they honor the past.
7. The capacity to relate to others: Persons are social animals; they form bonds with others, both intimate and collective.
8. Concern for others: Persons always reach out to others; non-persons draw into themselves, even pathologically.
9. Communication: Persons communicate with other persons; if they become completely cut off, they become sub-personal.
10. Control of existence: Persons take responsibility for their lives; those who do not guide their own behavior are sub-personal.
11. Curiosity: Persons naturally want to know. If they lose this desire to know, they are less human.
12. Change and changeability: Persons can grow into new phases of life; If they resist change completely and totally, they are sub-personal.
13. Balance of rationality and feeling: Persons have both reason and emotion; one who is distorted either way is not whole.
14. Idiosyncrasy: All persons are different from one another; the less individuality, the less personhood.
15. Neo-cortical function: Personhood requires cerebration; if the higher brain is dead, there is no consciousness, no personhood.
notice this is broad enough to include a normal 2 year old kid, a person with schizophrenia, a person with advanced Alzheimer's disease, or someone with Autistic spectrum syndrome.
And remember: few modern medical schools give the Hippocratic oath anymore...
Luckily, Americans have rights because they are granted by the Creator, but history is full of socieities commiting genocide on those they have decided are not fully human.
Father DeLasCasas, call your office....Paul III is on the phone.