It's the destroying of a genetically unique individual human that is the issue. No matter how far along the continuum of development they are.
Humans are just self-replicating collections of atoms that emerged through chance and evolution, and pain is just an emergent phenomenon formed by electrical impulses travelling over neurons to signal things that we evolved to avoid. So there is no absolute moral reason to protect the coherence of a particular collection of atoms over another, or to favour a doctrine of hedonism over pain.
Ultimately, to optimise for something, we need a criterion on which to optimise. For the above reasons, I consider preserving human biodiversity, or some kind of hedonic pleasure-pain balance as a fairly meaningless thing to pick as a fundamental thing to optimise for in the scheme of things (although it may emerge as a result of another more meaningful optimality criterion).
I consider the diversity of information / knowledge (that is, information that encodes something true about the world, not just random entropy) recorded in the universe in a form that can be processed by intelligently acting constructions to be a more fundamental thing to optimise for. Obviously, picking what to optimise for is completely arbitrary - it is used to justify everything, but it is like an axiom - there is nothing else to justify it in terms of.
Optimising for such knowledge means protecting the intellectual independence of constructions that create, process, and support the construction of such knowledge. Since this is primarily humans at the moment, this means ensuring that humans are not oppressed. Pain and fear of death are means of oppression of humans, and so it makes sense to ensure that living, thinking humans capable of knowing fear and feeling oppressed do not have to fear that they will be subjected to arbitrary death or pain for their intellectual activities.
One way to do this is to strictly enforce a no humans killing humans older then some certain amount of time after conception. If the amount of time after conception is too high, an age at which the person can know that they are at risk of death and fear it, then it will be oppressive. However, an embryo or fetus is very unlikely to be know that abortion exists, or to do anything differently to avoid it, and therefore abortion cannot be oppressive like murder or torture is. Anyone capable of knowing about abortion is too old to be killed deliberately by it.
No one would really know about or have reason to fear getting killed for at least a few years after birth at the earliest...
Please do not commit a red herring and a straw man by arbitrarily assuming that it would "require gods or souls" without providing any logical reason as to why it would.
2. Combinatorics, Not Morality.
Genetic uniquness is the complete antithesis of a "moral, supernatural, superstitious, spiritual" judgement - it is instead a cold hard evolutionary reason - see https://news.ycombinator.com/item?id=5393246 in these comments for why. In fact, you later support this - as noted below.
3. Pain, Fear, Death, and your Contradiction.
You assert that "oppressing and killing humans" is bad. Then you invent a new criteria - not based on oppressing and killing humans, but just whether they know they are being killed and oppressed. This has the following errors:
A. It contradicts your objective criterion of information. (Because it logically has to, as seen by 2)
B. It is more subjective, because it depends upon the human being aware of their oppression/death.
C. Not all humans are aware of their oppression or death (gunshot from behind) - your standard would then mean it is okay to let all those people be oppressed and die. I do not think that was what you were going for. (Note: this sounds like a ridiculous argument, and it is because I'm intentionally pointing out the rational absurdity of your vague criterion.)
D. You then conveniently "oppress" a human embryo by assuming that it is indifferent to dying - despite that its biological function is to keep itself alive (whether conscious or not).
E. Yes, so per your very own criterion, there would be no problem with defining that line as "0 days after conception" - so why not? Better safe than sorry.
Genetically unique? So it's ok to kill an identical twin?
Edit: Also, what is suffering and is it different from pain?
I had two qualifiers in there: unique and individual. Each twin is its own individual.
Once the egg is fertilized and becomes a zygote it is genetically unique.
(An ovum wouldn't implant. That would be a zygote.)
Ethics and morality in philosophy are generally based on minimizing the experience and perception of suffering, not promoting diversity - though diversity can certainly help reduce suffering.
Disclaimer: I have no expertise in the field of ethics and morality.
My girlfriend is however (has worked under Paul Bloom at Yale specifically in moral development, and is in a fully funded PhD program for moral development), and "minimizing the experience and perception of suffering" is not the "general basis".
Note: The author of the parent comment was not trying to make a moral judgement, but a biological and evolutionary one. That abortion is mathematically not beneficial - so there is no need to make a moral argument when there is a scientific one. (That is, not to say, that a moral one ought not be made.)
Certainly you can argue about a billion types of ethical frameworks, some of which may differ from this statement, and you can argue about the definition of ethics and morality. The prevailing basis of morality and ethics is most certainly minimizing suffering. Without sentient experience, ethics are meaningless. That's why in most frameworks we don't worry about the treatment of non-sentient things outside the context of the sentient experience of them, and we debate whether ethics apply to things based on whether they are sentient. Notwithstanding issues relating to these objects relationships to other sentient beings, we don't worry whether it's ethical to sit on a chair or pee in a toilet.
The parent comment was drawing an ethical conclusion from a biological fact, and certainly did not say anything about abortion being or not being "mathematically beneficial," whatever that means.
I am sure you were discontent with the summary, and had to scroll down to some other section which was closer to your bias.
I am also not sure how you can claim to know that the author /was/ drawing a moral conclusion, when he (just as you note about math) never said anything about it.
You asserted morality to trivialize his comment, I was merely pointing out the logical error in jumping from "biology and genetics" to "morality".
Throw morality out the door, and the point still remains.
I scrolled down to the part titled "Defining ethics," which happened to be the first section, thinking that would be applicable to defining ethics.
If you read author's comments in the thread, you will see he is clearly making the point that destroying a zygote is a moral issue, as he says:
> It's the destroying of a genetically unique individual human that is the issue
in response to a question about whether destroying a zygote is "wrong".
Throw morality out the door, and he is stating that a zygote is genetically unique for some strange reason in a thread about the morality of abortion.
Besides, his implicit point is also wrong - that a zygote is distinctive in being genetically unique. Each sperm is also genetically unique, so it's a rather inapplicable statement to the context of the thread, unless masturbation is also a sin against the universe.
I don't do much voting honestly.
> I don't understand how if one is viewing the subject from a evolutionary genetic perspective, why it is wrong to say that mechanisms that go against evolutionary development (abortion) are wrong
If anything goes against "evolutionary development" it is using technology to increase genetic diversity without regard to fitness.
Anyway, abortion does not go "against evolutionary development" any more than celibacy or monogamy.
Directed evolution is a whole different ball game that presupposes an active god or a detailed master plan. Either way, that is not evolution as most scientists would view it or as Darwin theorized. And regardless, humanity is not at risk of spoiling such plans.
Each sperm is also genetically unique.
And your definition would allow the abortion, or even adult slaughter, of a twin, or two of a triple. That is an interesting opinion.