When Does Human Life Begin?

The essence of the pro-life argument against abortion is their belief that “life begins at conception”. They declare that this isn’t just their opinion; science itself says so. They claim that biologists are in broad agreement on this fact. And if we’re simply talking about the organism itself, they’re 100% correct. When an egg is fertilized, and becomes a zygote, it is unquestionably a new life – one that (if all goes well for it) will eventually develop into a living, breathing person.

So, since the zygote is alive, and since we’re talking about human zygotes, they reason that the zygote is a human life, and that abortion is therefore the intentional taking of a human life (i.e. murder).

But this argument pretends that there is no significant qualitative difference between the “humanity” of the zygote, and that of a living, breathing person, when in fact, the differences are enormous and profound. So the more critical question is whether the zygote is truly a “person”. That’s a question that science alone can’t answer, because determining what truly defines a person, is a philosophical, not a scientific question. Science can only describe the qualities and nature of a zygote (or embryo or fetus).

Pro-lifers will argue that our humanity/personhood is defined by our DNA. Our DNA IS different from all other species, but some fairly significant mutations can occur, and the person is still considered to be human. But at conception, the function of DNA is to manage the workings of the cell, but more significantly, it provides the instructions that will cause this cell to eventually develop into a baby. The DNA is not the person, it’s the instructions for creating the person.

Humans are complex beings, with numerous traits that distinguish us from other animal species. Many, of course, are physical traits. Our bodies have a variety of features that are obviously different from even our closest related species, but those physical traits don’t define our personhood. We could lose all our limbs, and have numerous internal organs transplanted (sometimes with animal parts) or have organs replaced with mechanical substitutes, and few, if any, would argue that we are no longer persons.

Carrying that to the extreme, there is only one feature that is inextricably linked to our personhood – our minds. If a person suffered severe trauma, such that most of the body could not survive, but we could transplant their brain into a machine which could keep it alive, allowing it to interact with the outside world, that PERSON would still be alive. Conversely, we already have numerous examples today in which a person may lose all brain function, with their body otherwise unharmed. We can keep that body alive through the use of machines, but unless there is some reasonable hope of recovery, we don’t. Instead, we decide that their human lives have effectively ended, and we unplug them.

A person is the sum total of their experiences, memories, personality, intelligence, emotions, values, etc. When someone loses all brain function, those things are lost with it. The “person” is gone.

I’ll note that this is not the case for someone who is unconscious or in a temporary vegetative state. They may no longer be aware of their environment, potentially being temporarily non-sentient. But in this case, the “person” still exists within the unresponsive brain.

So if personhood ends with the loss of the mind, it follows that personhood doesn’t begin until the mind exists. So when does that happen? Unfortunately there is no black and white answer to that. On one extreme, the zygote clearly has no mind. On the other extreme, a newborn baby clearly DOES have one, as evidenced by (among other things) the fact that it’s capable of learning.

The fetal brain begins to develop at about 3 weeks, with the first neurons forming. At 5 weeks, a neural tube has formed. Electrical activity in the brain begins at about 8 weeks, which begin to initiate involuntary muscle movements in the womb. By 10 weeks, there is a recognizable brain structure, but it’s smooth, without the characteristic folds of a fully-formed brain. The fetus still has no cerebral cortex, and is non-sentient (i.e. unaware of either itself or its environment). While it may respond to external stimuli, the reactions are purely reflexive. It can feel no pain.

The onset of sentience occurs around 24 weeks. It is only then, that the fetus begins to become AWARE of external stimuli, including feeling pain, etc. But while the fetus is sentient, it is not yet sapient. It can feel, but it cannot think. It has no memories, no emotions, no personality, etc. It is still not yet a “person”. For that, the fetus requires not only sentience, but some degree of sapience.

And this is where things become VERY gray. Gradually over about the next 16 weeks, the fetus evolves from being merely sentient to becoming sapient. That evolution continues after birth, and in fact, the brain takes decades to fully mature. There is no single moment that defines the transition to sapience. Therefore there is no clear-cut moment at which we can say that the fetus’ human life (aka its personhood) has begun. But we know it’s not before about 24 weeks,

In my discussions with abortion opponents, they will commonly argue that these aren’t the same. If someone is in a persistent vegetative state, and it’s determined that there is little to no hope of recovery, that’s entirely different from the fetus, which has a pretty good chance of becoming a fully functioning person. While that’s true, that doesn’t change the fact that the early term fetus is NOT YET a person. Terminating the pregnancy does not kill a person, just as terminating life support for one who is brain dead, does not kill a person (that person is already gone).

Between the 1973 Roe v Wade and the 2022 Dobbs v. Jackson Women’s Health Organization decisions, the various states allowed unrestricted abortions until around 24 weeks (give or take, depending on the state), with later exceptions for severe fetal abnormalities, or to protect the life/health of the woman. The 24 week threshold is not entirely a coincidence. Those laws have typically been based on fetal viability, but it’s not surprising that fetal viability would be correlated in part to brain development. While advances in medical technology will likely continue to improve the viability for younger (earlier-term) fetuses, these are unlikely to accelerate the onset of sentience.

But given those laws, my perception is that they gave plenty of time in the overwhelming majority of cases, for women to become aware of a pregnancy, to decide if they wanted to carry it to term, and to get an abortion if not.

At the risk of inviting the “no uterus, no opinion” reactions from women, I personally think those laws were pretty good, and I’m uncomfortable with suggestions that abortion ought to be completely unrestricted, because I agree with abortion opponents, that the personhood status (from a philosophical and scientific perspective) isn’t materially changed when a baby leaves the womb and takes its first breath. (Though obviously the LEGAL personhood status DOES change at that moment).

A primary argument from many pro-choicers, is the right of women to bodily autonomy. I absolutely agree with it, but I think the argument becomes weaker as the pregnancy continues. The woman has that right, but early in the pregnancy there is, as yet, no “person” in the womb that could have any competing rights. Late in pregnancy, however, that’s not the case. At that point, there are valid ethical questions as to whether bodily autonomy should take precedence over protecting the life of a sentient being.

I draw an analogy to a situation in which I’m holding onto someone to prevent them from falling off a cliff. At that moment, the other person is completely dependent on me for their survival. But do I have an obligation to give up my own autonomy, and continue holding them? If I can do so without risking my own safety, most people would agree that it would be unethical to let that person fall to their death.

It’s really not much different than if one is driving along, and a person walks in front of your vehicle. Even though you have the legal right of way, you also have a legal obligation to attempt to avoid hitting that person, IF you can do so without significantly endangering yourself or others.

These competing interests were overtly recognized in the Roe decision, and resulted in laws that adopted a reasonable balance between those interests. Since the Dobbs decision, many states have abandoned that balance, and rejected any notion of a right to bodily autonomy, while absurdly granting rights to a single cell.

It is my opinion that we need to restore the balance that was established by Roe. I believe that women should have an unrestricted right to abortion for about the first 24 weeks, with later exceptions for cases of severe fetal abnormality, and to protect the life and health of the woman. The approximate 24 week threshold is not based on viability considerations, but rather the criterion of sentience discussed above.

I do not support unrestricted abortions throughout pregnancy. And for what it’s worth, I believe that those who push for this are hurting the greater cause, by shifting the debate to that extreme position, rather than focusing energy on the more moderate position that has pretty widespread support. I see little chance that pro-lifers will be persuaded by any argument that denies personhood considerations for late term fetuses, or declares that those considerations are completely irrelevant in the face of rights to bodily autonomy.

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