The underlying premise in the arguments pro-abortionists give against fetal personhood is
that non-persons can change into persons. They are saying that a living being can undergo
a radical, essential change in its nature during its lifetime. But there is a logical
problem here. If the change was biologically inevitable from conception, given time, then
this change is not a change in essential nature.
This is because if the being naturally initiates the change, it must be in its nature
from the beginning to do so. If it is in its nature to do so, then despite any changes in
such characteristics as independence, place of residence, physical development, or
demonstration of mental ability, what the being is in later life is what the being is from
the beginning of its life.
This means that if we are persons with the right to be free from aggression later in
life, we are persons even at conception.
