Having been in a number of abortion debates, on and off the politics forum, it always seems like the winning position is an abortion cutoff in the mid-late 2nd trimester. The most radical positions that are common among Pro-Life and Pro-Choice organizations seem to be obliterated almost immediately. Very rarely is the position that abortion should be illegal from the moment of conception taken seriously, and likewise almost no one argues that abortion should be legal up until the moment of birth. Yet these are the positions that major Republican and Democratic candidates take.
Just out of pure boredom, I decided that it would be fun to play devil's advocate and try to create arguments to defend the two radical positions.
Defense of complete ban on abortion from the moment of conception
The laws of the United States are based on the principles of personal liberties and freedom of choice. People have the right to make choices, but the government exists to prevent people that make choices which violate another person's liberties.
The legal value and personhood of an individual is related to both the person's current state and potential future state. Consider the issue of euthanasia. If you agree that it would be ethically permissible to end the life of a terminally ill cancer patient, then you must agree that a person's legal value is determined by both their current state and their future potential.
The stem cell immediately following conception is worthy of basic legal protection because it will
eventually grow and become a person.
A common argument made against the potential value argument is the claim that the non-united sperm and egg are a person. This, however, is absurd because there is a significant difference between a sperm and an egg and the fertilized egg. The blueprint for how the person will develop cannot be reliably predicted from just that sperm and egg, and likewise the outcome of a collision of many sperm and a single egg is highly chaotic. There is no single, most likely, set outcome from that event.
To support this with an analogy, let's say I own a stock of a new start up company called Stall Mart. At this point, Stall Mart is an idea that a few friends have thrown out. They have a bunch of different models and ideas being thrown around, and there is still no consensus on what the store will actually be. None of the concrete has been laid down, and very little research has been done into the market. How much would you pay for such a stock? Very little, I'm guessing. How many investors on Wall Street do you see putting real money on companies where there isn't even a developed business plan?
Now, a few years later, Stall Mart has a few researches together, there's a solid business plan, and the first store is built and ready to open. How much would you pay for a stock of the company? Obviously not as much for a company that's already open, but you still would be able to find some investors. It has some value because development is underway and a business plan has been developed.
Note that even though both companies are just potential businesses, the one that has began development and has a single plan is more valuable than the one with multiple potential plans, and no development underway.
Likewise the stem cell after conception and the sperm/egg are both potential persons, but the stem cell after conception has significantly more value because the person's DNA (the plan for development, if you will) is laid out, and most of the development that will lead to the baby is underway and set in stone. The person is worth more in the eyes of the law, just as a stock is worth more in the eyes of the market if its futures are more predictable.
Therefore, abortion after the moment of conception violates the natural rights of the developing person, and should be illegal under law.
Defense of legalization of abortion until the moment of birth
The central moral issue in abortion is the person hood of the zygote/embryo/fetus. If the fetus is not a person, then there is no sensible reason why the woman should not be allowed to abort it.
What a person becomes is determined by both their DNA and their environment. A person is not a unique person because they have unique DNA. If I took a strand of your DNA, made some changes to it, and then put it back into a cell, would you consider that to be a unique person? And likewise two people with identical DNA are not considered to be the same person.
Therefore, the basis of person hood does not come from unique DNA, but comes from having a unique DNA and a unique environment.
A fetus, until it is born, is simply a function of its DNA, since it has no contact with a substantive environment. If we are to be consistent with our attitude that identical twins are unique persons, and that unique DNA does not constitute person hood, then we must conclude that the fetus is not a person.
When the fetus is born it becomes a function of its environment as well as its DNA, and is therefore a unique human being worthy of rights.