A fetus is NECESSARILY an individual, as it has a unique DNA; NECESSARILY human, as it is not a monkey or a porpoise; and NECESSARILY a being, as it exists
I am glad you brought this up. My 'official' position is pro-choice, and I do think this is an important question. Some radical pro-choice people do not. Radical pro-choice, held by very few, holds that even if the fetus is a human, it has no rights, because it is sort of parasitically dependent on someone else for it's survival. I think it is perverse to hold such a position.
So, for those of us who agree that personhood is an important factor in determining whether abortion ought to be allowed, you raise a very important question. It rests on first deciding what a human is, and then on deciding whether a fetus fulfils that definition. I think it's best to separate the two steps because then its much easier to approach the subject rationally. Because the subject has not progressed in this thread very far, it seems reasonable to me to set aside saying whether a fetus fulfils the definition of human until we've discussed what human means for a while.
You first proposed defining 'humanhood' thus:
All things that meet the following three requirements are human things:
- It has unique DNA
- It is not any other 'animal'
- It exists
But, I think you quickly made your definition more precise. You were reminded that some things that are presumably separate humans don't have unique
DNA, namely identical twins. I bet the thing that meets your requirement for item 1 is simply that a human must have human DNA.
I would quickly point out that the next two items are not necessary. No other known animals have human DNA, and everyone's definition of a human would surely only include those things that exist. So, unless you object, your definition is left with "All things that have human DNA are human things". I am not sure you would want to stick with that, without further clarification. Live human blood in a petrie dish has human DNA, and it fulfils your other requirements to boot, should you choose to stick with them.
It seems like you may have been trying to clarify this issue when you stated:
... humans can SHARE a DNA and be individual, they cannot have a seperate genetic makeup and still be the same being.
But, this does not seem to add anything to your definition. It still says at most that a thing that is human must have human DNA, and nothing more.
Would you like to clarify your definition?