A political leader recently shared a story where he nicknamed his unborn daughter "Bean" because of the shape on the ultrasound, a nickname that stuck through her life. His opponents grabbed that phrase, saying that fetuses are not humans, but seeds. They are not life, but potential life, just like a bean is only a potential plant.
Whether or not a fetus is a human being is the core of the abortion argument. If a fetus is not a separate, distinct, living organism, removing it is no worse than removing a tumor. If the fetus is a human being, its own person, than killing it is wrong no matter the circumstance, no different than murdering a child, an elderly person, the handicapped, or any other human being. There is no gray area.
I would like to bring up a couple points from botany, building upon the "fetuses are like beans" statement.
First of all, a seed contains an embryo. This embryo is a distinct living organism from the parent. In both humans and beans, the embryo is formed from the fusion of DNA from each parent. Each parent created a reproductive cell which contains half of the parent's DNA. This means that the offspring may have genes that were masked in the adult, and therefore have traits that neither parent possessed. The two parents' reproductive cells come together and the DNA fuse together to become a separate, distinct being. The main difference between these two embryos is that the bean has the ability to go dormant and wait to be "born" until conditions are favorable.
Second of all, plants have an interesting trait called "alteration of generations". In a nutshell, this means that the plant's children look nothing like it, while its grandchildren do. The plant's daughters (which have only the half-set of DNA) live inside the ovary and create both the egg for reproduction and later the "food" inside the seed that will sustain the embryo. The plant's sons become pollen, which transport, bore into the ovary, and produce the sperm. The embryo, which is the fusion of egg and sperm, is technically the grandchild of the parent plant. But the big question in all this is: why do scientists consider the pollen and the female gametophyte to be separate living things, a completely different generation than the parent plant or the seed? The answer is simple: because they are multi-cellular. In this case, merely having more than one cell is enough to make you a distinct living organism, as far as science is concerned.
The main point here is that both beans and babies are distinct organisms, not merely parts of their parents. Indeed, in the plants' case they are not even parts of their parents. An embryo is a separate entity from the moment it is formed. A fetus, therefore, is its own distinct person, regardless of where it happens to be. Neither the bean nor the baby is a "potential life". Both are, in fact, lives with potential.
If you look at different cultures from all history, you will find that murder is considered wrong by the great majority. Killing another human being is a crime in almost every culture. Obviously, murders still happen, including ones sanctioned by the leaders of the culture in question. This happens most often when the victims are labeled "sub-human", so that in the minds of the aggressors they do not count. Countless examples of this exist through history, from Nazis to US slavery to Rwanda's genocide. The same is happening now. Pre-born babies are considered subhuman, even sub-animal (there are laws against killing many animals without a viable reason), so it is no crime to murder them for any reason.
Our culture prides itself on not being racist or sexist. Perhaps we should take the next step and stop being developmentalist and agist.