This argument is developed in Beckwith (2007), and in George and Tollefsen (2008).
This presentation here is based on Beckwith’s emphasis that fetuses and the adults they often later become are the “same being.” These arguments, however, can be interpreted in a more complex way, in which we understand them as arguing that having rights, or the properties that result in having rights, is to human beings, meaning that we have rights whenever we exist (and so since a fetus and the later adult are the “same being” they have rights whenever they exist).
BIOLOGY does not settle things: if being a biological parent automatically creates al the obligations of parenting, then sperm donors have all the responsibilities "of a social father." (In other words, one sperm donor might be the biological father of a hundred children, so if being a biological parent automatically creates al the obligations of parenting, then the donor would have to pay to raise all of them!
)The decision to abort is most often a rejection of the RELATIONSHIP of motherhood & the reshaping of life that it entails.
The medical and scientific research reports that this developmental stage isn’t reached until after the first trimester, or, more likely, until mid-pregnancy.
But aren’t our futures plausibly valuable, in part, because we can, presently, look forward to them?
While some people see abortion as murder, others believe that abortion should be allowed in the case of ‘unwanted’ pregnancy.
This is when the pregnancy was not planned, and the mother is either not ready to have a child, or the birth of the child may pose a danger to the mother and the child.
This more sophisticated argument is not discussed here.
Nathan Nobis is an Associate Professor of Philosophy at Morehouse College, Atlanta, GA USA, and author of many articles on topics in bioethics, including abortion.