David Farrar of Kiwiblog weighs in on the abortion debate. I have met David a couple of times and worked with him on several issues and I have a lot of time for him but on this issue we disagree. Given how widely read Farrar’s blog is, and seeing the ethics of killing a fetus was my PhD thesis topic, I will endeavour to spell out why I think he is mistaken.
Now my personal position on abortion is it should be legal, safe and preferably rare. As cessation of brain activity is what effectively marks death, I tend to regard life as the start of such brain activity (as measured by ECG, not just electrical activity) which is at around 20 weeks.
Farrar’s argument here appears to consist of two premises (some which are more implicit than explicit). They are  If the loss of a property results in something going out of existence then the acquiring of the same property results in it coming into existence  the loss of a functioning brain (measured by an EEG) results in living human being to go out of existence and  A fetus acquires functioning human brain (measured by a EEG) at 20 weeks. Now  and  entails that a living human being comes into existence when it receives a functioning brain measured by EEG, and this conjoined with  entails that a living human being comes into existence at 20 weeks
I think Farrar’s argument is unsound because  is clearly false. Consider a functioning car. A functioning car ceases to exist as a functioning car when it looses a motor. Does it follow that then that all a car needs to become a functioning car is a motor? No, More than just a motor is needed to get a car to function, one needs petrol, a driver, wheels etc. The loss of a motor will stop it functioning but the presence of a motor is not enough to make it function. The point is that often there can be a series of properties each of which is necessary for something to exist but none by themselves enough to make the object exist. Something can be necessary for X but not in and of itself sufficient for X. Farrar’s argument confuses these separate things, it assumes that if something is necessary for X ( its absence causes X to not exist) then its sufficient for X (its presence causes it to exist) and this is simply an error.
There is however an analogue of Farrar’s argument which has more promise and it has been proposed by ethicists such as Goldenring, Hans Martin Sass and Baruch Brody. This argument suggests that we already have criteria which we use after birth to determine whether a human body on a life support system is a living human being or merely human tissue (a corpse). This is the famous “Brain Death criteria”. According to this criteria if a human body posses a functioning human brain then it is a living human being and killing it (by harvesting its organs for example) constitutes homicide. On the other hand if it does not have a functioning human brain then it is dead, it is not a living human being and one does not commit homicide if one slices it up.
These ethicists suggest that we apply this criteria to pre born situations. Early in the pregnancy a rudimentary human body emerges. The uterine environment is moreover analogous to a life support system. We want to know whether this body constitutes a living human being or a mere tissue. They suggest we apply the Brain death criteria. If the fetus posses a functioning human brain then it is a living human being and killing it is homicide. If it does not then abortion only destroys human tissue.
So, suppose I be charitable and reconstruct Farrar’s arguments along these lines. Do we have an argument that a fetus is not human until 20 weeks gestation?
No, the reason is that Farrar appears to not understand the brain death criteria. According to this criteria a human body is dead (as opposed to alive) if it posses a brain that has irreversibly ceased to function. It’s not enough that there be no brain function it must also be the case that such function will not come into being in the future. For reasons like this, many ethicists like Goldenring, Sass and Brody who appeal to the Brain death criteria conclude that a fetus is a human being from very early in the pregnancy around 6-8 weeks gestation. The reason is simple, around this time a fetus has developed a rudimentary brain, it posses some function and full function will come about in the future through natural brain development. Hence the fetus cannot be said to have irreversible lack of brain function.
The application of brain death criteria then in fact brings about precisely the opposite result to what Farrar contends. It leads to the conclusion that at the time most abortions occur a fetus is a living human being and abortion is homicide.