Final answer:
The liberal position on abortion generally regards the fetus as lacking the full moral status of personhood until birth, thereby making abortion morally permissible, as it prioritizes the rights of the pregnant person.
Step-by-step explanation:
The liberal argument presented suggests that if an unborn person is not considered a person until birth, then it is not wrong to terminate a pregnancy since it is wrong to kill a person only after they have obtained personhood at birth. However, the question appears to conflate the liberal position with the specific view of philosopher Mary Anne Warren, who argued that a fetus does not satisfy the characteristics essential to personhood and that abortion is always morally permissible. Broadly speaking, liberals argue for a pregnant person's right to bodily autonomy, weighing it against the rights of the fetus, which they may not recognize as having the same moral status as a birthed person.
The perspective that Warren and many other liberals hold is that the rights and considerations of the person carrying the pregnancy almost always override the moral consideration for the fetus. Importantly, this view recognizes the value of potential life but places the pregnant person's rights and welfare at the forefront. It is also worth noting that views on abortion can vary even within liberal circles, where some may posit restrictions based on developmental stages or viability, as seen in the Planned Parenthood v. Casey Supreme Court decision.