Richard at Philosophy, etc. has provided a post that contains a slew of bad pro-choice arguments for why abortion should be legal based on philosophy so I thought I'd respond.
His comments will be in blue.
Secondly, the question of whether abortion should be illegal is a separate matter from whether it is immoral. Some conservatives have fundamentally misunderstood the relation between law and morality - they do not recognise that sometimes immoral things should nevertheless be legal. But it should be obvious that this is sometimes true - consider lying, breaking promises, adultery, or (to a Christian) worshipping false idols. So the only question is whether abortion, too, is such a case. I think it is. Outlawing abortion would not stop it from occuring. It would merely drive the practice 'underground', making it far more dangerous. To outlaw abortion would put women's lives at risk. Even those with moral qualms about abortion should not be willing to pay the hefty social costs of such legislation (or, at the very least, it should give them pause).
Richard feels that abortion is immoral but that it shouldn't be illegal in the same way that lying, breaking promises etc. are immoral but not illegal. The question I would pose to Richard is "why is abortion immoral?" If abortion is immoral because it intentionally takes the lives of innocent human beings, shouldn't it be illegal? Are there other times when the intentional taking of innocent human lives should be legal?
Second, his defense of his reasoning doesn't match up with his reasoning. The immoral things that aren't illegal that he lists are acts that don't physically injury another human being. Abortion does.
Third, the question of whether an act will still happen even if it is illegal is no reason to keep something legal. For example, rape occurs every single day. Outlawing rape hasn't stopped it from occuring. Does that mean that rape should be legal? If rape was legal wouldn't it occur in "safer" places under "safer" circumstances? Another example - robbery - should we make picketpocketing legal so criminals won't be forced into attempting dangerous armed robberies? Of course, not. That position assumes that robbery is a good thing that should be legal in the same way that Richard's argument assumes that abortion is something that should remain legal. He is assuming what he is trying to prove.
More controversially, I think the reasonable person should agree that conception is not a metaphysically magical moment. The idea that 'life begins at conception' is contradicted by biology (a point powerfully made by Prof. Lord Robert Winston in a lecture I heard last year - I only wish I could remember it better). Scientists have created healthy mice that were never 'conceived' as such - the egg was artificially stimulated into replication and growth despite not being fertilized (I don't recall the exact details - possibly two of the mother's eggs were fused together to get the chromosome count right). And what to say of identical twins? Two persons formed from a single zygote - you do the math.
Who said anything about magic? Sounds like poisoning the well. Since Serge has spent ample time and energy refuting this argument here, I'll refrain myself and provide his illustrative work.
Perhaps most telling of all is the sheer fact that "between 60 and 80 percent of all naturally conceived embryos are simply flushed out in women's normal menstrual flows unnoticed". How does the proponent of life-at-conception deal with such a fact? Or, as Jason asks, "Why aren't they doing something about the 60-80% of all innocent human lives that nature spontaneously terminates? This stuff makes the tsunami look like nothing at all."
For one, Richard fails to mention that the same site where his information comes from also says, "It is estimated by multiple sources and authors and has been for decades that at the very beginning of life, of human development, of conception, about 50 percent of all potential human beings have a chromosome abnormality, mostly a lethal chromosome abnormality. Chromosome abnormalities are the commonest cause of death in humans. They kill at the very minimum two-thirds of potential humans, more likely 80 to 90 percent and they mostly do so through these lethal aneuploidies."
These embryos/zygotes die because they have lethal chromosome abnormalities, not because they were intentionally killed. It's very difficult/impossible to do something about lethal chromosome abnormalities in zygote/early embryos. The vast majority of abortions intentionally kill innocent human beings that would develop into healthy infants, toddlers, adolescents, etc.
Proponents of life deal with these facts because we recognize that because large percentages of human beings die naturally that doesn't logically lead one to the conclusion that it should be legal to intentionally kill human beings at the same or later stages of development. If I'm in a developing nation where large percentages of infants die relatively soon after birth, does that give me the right to intentionally kill infants?
Single-celled zygotes are not persons, nor are they somehow "morally equivalent" to persons in any sense that entails a 'right to life'. To suggest otherwise would seem to entail that we have a moral duty to constantly monitor all sexually-active women, to save those "human lives" that would otherwise get flushed away without anyone ever knowing. But we have no such duty, and any suggestion to the contrary is absurd. Menstruation is not manslaughter. Those cells are no more 'persons' than are the cells in my fingernail clippings.
His first sentence is a complete assertion that has no basis in fact or reasoning. He doesn't even arbitrarily define "personhood" for us. Nor does he tells us why they're not "morally equivalent."
How would we "save" the lives of week-old embryos with lethal chromosome abnormalities that haven't attached to their mother's uterine wall when we don't have the medical technology to save most children born at 22 weeks? His example is simply ridiculous. No one is saying that menstruation is manslaughter. This is a strawman argument.
He then goes on to confuse parts and wholes. His fingernail clippings are part of a larger human organism, Richard - philosophy student - they aren't guiding their own development- while an unborn child is a whole human being guiding its development.
These examples are also attempts to focus on the zygote/early embryo. He's defending abortion which intentionally kills older embryos/fetuses who have legs, arms, heartbeats, etc. but yet he's describing the unborn as "cells." Proponents of legal abortion can't defend killing 8-24 week-old fetuses so they spend time attacking zygotes, an entity which is never aborted.
Pharyngula offers some helpful diagrams to illustrate this point, and comments:
Figure 1. These are children. Figure 2. These are embryos. I can tell the difference between 1 and 2. Why can’t you?
When you tell me you think an embryo is the same as my kids, you cheapen the worth of my children. They are much, much more than that small thoughtless blob. You reduce the value of family to mindless chemistry and metabolism.
Imagine the pictures.
Figure 1. This is me - a 6'1, 170 man
Figure 2. This is my niece - a month and half old baby who weighs around 10 pounds.
I can tell the difference between 1 and 2. Why can't you?
It is true that Pharyngula's children are more developed mentally and physically than an unborn child but I am more developed than my niece or his children. Does saying that his children, my niece, and myself have the same right to life cheapen the my worth or reduce my value? Of course not. Since when do we grant the right to live based on mental or physical development or on how a human being looks? Should I have a greater right to life than his children and my niece because I'm larger and more developed?
I also find it interesting that he posts pictures of day-old embryos and not an 9 week old fetus or a 20 week old fetus - then the difference between his born children and unborn children might appear less drastic.
Richard then goes on to quote David Velleman from the Left2Right blog.
Lastly, there is everything David Velleman says, from which I'll quote a few key points:
When we ask whether the fetus has a right to life, we make it sound as if there is a single thing, life, to which some beings have a right and others do not, or to which some beings have a stronger right than others. Yet what gives persons a stronger right to life than penguins, and penguins a stronger right to life than petunias, is precisely that these beings live very different kinds of life: the life of a person is a different process from the life of a penguin or a petunia. The reason why different creatures have different rights to life is that some kinds of life-process require stronger justification to end than others and result in greater wrongs when ended without justification So there is no one thing, life, to which different creatures have different rights; rather, there are different kinds of life, with different entitlements to continue.
The belief that a human conceptus is not yet a person in the early stages of gestation rests on the fact that it is not yet capable of the beginnings that make a person's life wrong to end. It is incapable of those beginnings because it does not yet have any mental life.
Here are some of the relevant developmental milestones.1 Synapses do not begin to form in the cerebral cortex until the 12th week after conception, and neurons continue migrating into the cortex until the 20th week, which is the first point at which electroencephalographic activity appears. The fetus's EEG doesn't coalesce into "waves" until in week 26, or develop the patterns characteristic of waking and sleeping until week 30. Synapses begin to connect the spine to the thalamus in the 20th week and reach the cerebral cortex between weeks 24 and 26; not until the 29th week do peripheral stimuli evoke measurable potentials in the cortex, indicating the completion of functional sensory pathways.
Most importantly, Velleman fails to note that human fetuses and born human beings are the same kind of creature. A human fetus isn't a penguin or a petunia - she is human being. Different creatures do have different kinds of rights but human creatures should all have the right to life. His whole notion is based on the incorrect opinion that certain kinds of human beings are different types of creatures.
He then goes on to assert an arbitrary meaning of "personhood" and provides no reason why anyone should accept his reasoning over the reasoning of someone who says that "African-Americans are persons because they have a darker shade of skin."
Do newborn infants have a "mental life?" Not as far as I can tell. What are they thinking about? Do they have conscience memories? Nope. Are they self-aware? Nope. My cats have a greater mental life than newborn infants - does that mean they should have a greater right to life.
Velleman, why are your "milestones" any more "relevant" than other arbitrary "milestones?" For example, being able to talk or walk or think at high levels. Why do neural connections and synapses (something we don't control) matter compared to my "milestones?"
Richard then goes on to state that he's not even sure if infants are "persons." Which shows us exactly down what kind of road this arbitrary defining of "personhood" takes us.
I apologize for the ridiculous length of this post.