OK, so we've heard the rhetoric on abortion. According to one side, their opposition is made up of misogynistic sadists hell-bent (or would they say heaven-bent?) on telling women what they can and can't do with their own bodies. The other side says their opposition is made up of infanticidal maniacs with a thirst for blood that would make Hitler puke.
They obviously both can't be right (unless it honestly is a fight between misogynists and infanticidal maniacs; in which case they both suck). How do we reconcile this? I'm glad you asked, because I have the solution. Well, if not the solution, at least the only logical question that need be asked:
At what point does human life begin?
This is the hinge point upon which the entire debate turns. If something is a human life, to end it would be to kill it. If something is a mass of cells within the body, to end it would be to simply separate a piece of the body; like one might a mole or tumour. By proxy, if the thing growing within the womb is a human life, to destroy it would be killing a human life (I won't say "murder," because that would depend on context). If it is not a human life, to tell someone they cannot destroy it would be limiting one's personal liberty.
So the only question that has any significance is that of the point at which a person becomes a person. Is it the zygote? The embryo? The sperm and egg? Live birth? Ability to survive outside the womb? The answer to this question is the only thing that matters in this debate.
This has been thought of as a 14th Amendment issue, but it's actually a 5th Amendment issue (same wording and applicability as the 14th, in case you were curious; it's just that the 14th is more fun to use): No person shall be . . . deprived of life, liberty, or property without due process of law. If a fetus is alive and is killed (not by accident nor by medical expedient, such as to save the life of the mother) without due process of law granted to all other people in these United States, it is a violation of this amendment in that someone's life has been taken without due process. If, however, a fetus (or embryo, or zygote) is not alive, depriving a woman of her right to do with her body as she pleases would be a violation of this amendment as it deprives her of liberty without due process. And you thought the Constitution was just an outdated document written by a bunch of old fuddy-duddies; silly fascist!
With the preamble out of the way, on with the arguments! We're going to consider the scientific arguments for when a person becomes a person. There are various other angles with which to attack this debate, but none with as much rationality and objectivity (such as the religious argument, the historical argument, the cultural argument, etc.). There still exists ample room for interpretation in every view, but I'll try to cover the intrinsic problems therein. We'll go from furthest out from conception to closest into conception (I'm not touching any of the pre-conception arguments because I think they don't fall within scientific bounds, weak arguments to the contrary notwithstanding).
One argument for the beginning of human life centres around the concept of the fledgling organism being able to live outside the womb. I will refer to this as the Viability Argument. Its proponents advocate a person becoming a person when they are able to autonomously live outside the womb. The current point of gestation for this argument is 21 weeks and 6 days. I say "current" because this is technologically limited. Should technology advance to the point where a premature baby of younger than 21 weeks and 6 days is able to survive, this definition will, obviously, change.
Herein lies the major issue with the Viability Argument: consistency. Whereas the definition is quite specific (able to live apart from the mother), it is not constant. If a person is a person at 21 weeks and 6 days or beyond, what happens if medical science is able to advance to the point where they can save a 20 week old? Is that organism not granted rights until 13 days later? If someone purposely kills a premature infant, who was delivered at 20 weeks of gestation, at 21 weeks and 5 days, is it murder? You can see the problem. This argument's inherent weakness is that it is limited by technology, and not definitive of the organism itself. While it has some good points (and is in use in places), it is too weak to be conclusive. Also, by defining a "human life" as one able to live on its own, would this redefine others as not alive? A person on a life-support system, or a toddler unable to fend for themselves; would these become non-life?
I don't think it would go to that extreme, but suffice to say there is a logical problem with the definition should it apply to all human life (as it must should it be used for this purpose).
Next up: the Neurological Argument. Proponents of this viewpoint define life as starting when the brain is developed, anywhere from 8 to 25 weeks. The earliest (8 weeks) argue that basic brain formation is the start of human consciousness, while the latest (25 weeks) argue that consciousness begins when the organism displays an individual EEG pattern. There are also some in-between who argue for around 20 weeks because this is when the thalamus is formed, thus the organism has the capacity for rational thought (though, as we know from Congress, "capacity" and "ability" are often two separate animals).
The EEG argument seems to make the most sense of the three for no other reason than consistency. This is a common measure used to determine the end of life for a human individual, so it seems consistent to also use it as the measure of the start of life for a human individual. The problem comes in when we look at the youngest premature baby to have survived (the aforementioned 21 weeks and 6 days). If life does not begin until there is a specific EEG pattern, could someone have killed the youngest premie on the basis that it was not yet alive? I hardly think anyone would argue for that. Still and all, the Neurological Argument has quite a bit more logical credence than the Viability Argument.
On to: the Embryological/Gastrulation Argument (use that word at your next party; nothing gets girls like nerdy sciencey-talk). This argument puts the beginning of human life at about twelve days after conception. At this point, the possibility for "twinning" (the super-creative phrase they came up with for "making twins") is exhausted. The argument states that, prior to this point, the existing zygote may or may not become more than one individual life form. Should we grant "humanity" to the zygote prior to this point, thus labeling it an individual, how will that label stand should the zygote undergo twinning? Would the twins be classified as a single entity? To offset this potential pitfall, the Embryological/Gastrulation Argument posits that we cannot call a zygote a human individual prior to roughly twelve days after conception because we might erroneously label two or more people as a single life form.
The problem with using this argument as a timeline for abortion ought to be manifest, but I'll pretend that it isn't and explain it. Nothing in the argument shows that the zygote is not alive, but rather that we don't conclusively know how many lives will result from said zygote. While it might make a nice litmus for labeling "individual," it's a poor choice for labeling "life."
Our penultimate argument to view: the Genetic Argument. This argument places the beginning of life at about 24 hours after conception. This is roughly the time it takes for the egg/sperm mix to form a new, unique genome. This argument states that, since the organism has a separate genome than either parent, and the genome is human in nature; it is a separate, individual human life form. This argument is both clean and fairly definitive, but it does have a few potential issues in today's "letter of the law," litigious society.
First, if human life is defined as an organism with a unique, human genome; what of twins? They have identical genomes (at least, identical twins do). Would they be labeled as a single life form? Second, what of cloning? Should a clone be made with a genome identical to the parent being cloned, is it not considered alive? Third, what of the dead? Aren't they entities with unique, human genomes?
There is some obvious room for fine-tuning, but I find the Genetic Argument to be the most logically sound (other than the last argument, which we'll get to momentarily). Of course, the other arguments have quite a bit of merit; but I have yet to see this one definitively disproven.
All that being said, there exists an inherent problem with each of the foregoing arguments: time and individuality. In order for a definition to be made law, one must put some real, tangible numbers to it. Let us take, for example, the formation of the thalamus at 20 weeks. Does everyone have a fully formed thalamus at exactly 20 weeks? What if someone gets theirs at 137 days? Would we make verification surgery mandatory for every abortion performed before, say, 18 weeks? Would we simply perform an autopsy on aborted fetuses and see if they had a thalamus, then charge the doctor and/or mother with murder if they did?
Obviously, whatever definition we arrive upon, in a legal sense, would have to allow room for the individual. Otherwise, it is not a true definition at all (in the aforementioned example of thalamus formation, if we arrived upon 20 weeks but were OK with aborting an 18 week old with a fully formed thalamus; then we are not really classifying it as a life since we are comfortable with ending it without due process).
This brings me to the final argument: the Reagan Argument. It's already awesome because it references The Gipper, but I'll go on to explain it anyway. In 1983, then President Ronald Reagan said the following in an article he wrote for The Human Life Review:
"If you don't know whether a body is alive or dead, you would never bury it."
This, to my mind, is the heart of the issue. The debate rages on as to whether this is a right-to-life or right-to-liberty issue, but it all hinges on whether or not the thing growing inside of a woman's womb is alive. Though I cannot say that a fetus is definitively, beyond a shadow of a doubt alive; I also cannot say that it is definitively, beyond a shadow of a doubt not alive. Not in any stage of development.
The real question, then, is this: on which side do you err when life is not clearly, indisputably shown one way or the other? Do you risk being a potential misogynist, or a potential murderer?