| Agreed about "first principles". This is how I'd frame the abortion debate: 1. Nearly everyone agrees that a normal adult has a rights over his/her own body. Eg, a tumor cell has no right to life and the host has every right to kill it.
2. Nearly everyone agrees that the parent of a toddler may not kill the toddler for any reason. Given these principles, at what point in existence does one qualify as having human rights and on what basis do we identify that point? Possible criteria include unique DNA (eg, from conception), heartbeat, ability to feel pain, a particular level of cognitive ability, etc. If a zygote is essentially like a tumor - not yet a human life - then abortion at that stage would be no different morally than having a tooth removed. If a fetus at 38 weeks is essentially like a newborn, then abortion at that stage would be no different morally than infanticide. In establishing the criteria for human life, we should consider as many implications as possible. Eg, if humanity is determined by cognitive development, do intelligent people get more right to life than average or impaired people? If we agreed on these principles and criteria, we could have consistent law. Currently we (in the US) have a hodgepodge; eg, abortion by punch to the abdomen is murder but by scalpel and consent at the same stage of development is just an elective procedure. |
That's an important piece of the argument. Is personhood innate (in which case it must begin at conception, sicne there are no other bright lines in development that make universal sense across culture and time)? Or is it a social construct (in which case we have no right to see abortion as different from Roman infanticide)?
In other words, is personhood and human rights innate, in which case you must be a pro-life extremist if you are willing to seriously argue that? Or is personhood socially recognized and constructed, in which case you must accept that abortion is infanticide but also that infanticide is ok if the culture says so? The thing is both of these are relatively extreme viewpoints. Very few on the right want abortion to be punished the same as infanticide, and very few on the left are willing to acknowledge that if abortion is ok, then infanticide must be too (but there are some, see NARAL and Planned Parenthood's defence of killing fetuses born alive after failed late-term abortions).
> In establishing the criteria for human life, we should consider as many implications as possible.
Doesn't that mean we should leave it up to local cultures to sort this out for themselves? If Rome wants to mandate infanticide in the case of severe birth defects, bully for them.