Debates about abortion, euthanasia, and the recent case of Alfie Evans all turn on the question of personhood.
We all agree murder is wrong, but what counts as murder? Most of us don’t think murder and killing are per se identical or morally equivalent. After all, if you eat meat, you most likely believe that taking life is not in principle wrong; and our current laws reflect this presumption.
Perhaps, you’d suggest, it’s not taking life that is in principle wrong, but taking specifically human life. Or perhaps taking innocent human life (since for most of human history, things like corporal punishment and just war have been relatively uncontroversial matters).
Modern ethical and political thought since the Enlightenment has developed a distinct way of talking about this issue: the language of “rights.” Government is founded for the sake of preserving rights; and the most fundamental right is usually agreed to be that of life.
Most Western legal systems operate on the assumption that rights are not predicated of humans qua humans, but humans qua persons. It is personhood, not humanity, that grants one rights, at least to many of our courts and governments.
So how we answer the question of what a person is, and what counts as a person, determines quite a bit.
Today, the notion of personhood is closely associated with concepts of individuality, intellect, will, emotions, desires, etc. For our sake, we can include all of these under the general label of “conscious mental activity.” On this view, a certain minimum level of conscious mental activity is a necessary prerequisite for attaining the status of personhood.
In all honesty, this view carries with it a certain initial plausibility. After all, when we speak of “persons” colloquially, something related to this notion is most often what we have in mind. Think, for instance, of common derivatives of the word person: personal, personality, personally, etc. Wherever you stand on the abortion question, it’s admittedly difficult to conceive of a fetus having a “personality.”
The problem is that our colloquial use of the word “person” does not accuratley reflect its historical meaning or significance. Traditionally, the word “person” has not been predicated of specific attributes, but rather of that which grounds those attributes. So Saint Thomas Aquinas defines a person as an “individual substance.” In particular, a person is an individual substance of a rational nature.
Human beings have rights/dignity/value/worth because human beings are rational creatures. Given this, what difference does it make if we define a person as an individual substance of a rational nature as opposed to an individual which possesses a certain minimum level of mental activity?
For one thing, the latter view is extremely problematic. How do we determine what that minimum level of mental activity is? There does not seem to be any non-arbitrary method of determination. Perhaps, one might say, if rationality is what gives humanity dignity, then the ability to utlize or realize rationality should be considered a minimum standard for personhood. But then we run into several problems: first, infants and young children don’t have developed rational abilities. Are we prepared to say that infants are not persons and have no right to life? And what about the fact that adult humans are not always in positions where they are actually using or realizing their rational potentials, e.g. such as while they sleep? Are we prepared to say that humans cease to be persons (and hence lose their right to life) while they are asleep? One could, of course, attempt to modify the principle such that it fits these various difficulties, but then it becomes difficult to see how the formation of the principle is not, as we’ve suggested, ad hoc or arbitrary.
The better approach is to say that human dignity is grounded in human nature; and human nature is possessed by any living human organism. An individual organism which possesses a specific nature is an individual substance within that nature, and hence is, in the relevant sense, a “person.” The implications, then, are that fetuses are both human beings and human persons, and as such have a “right to life,” meaning that killing them is wrong and thus that abortion is gravely immoral.
. Aquinas. Summa Theologiae. I, Q. 29, Art. 1. http://dhspriory.org/thomas/summa/FP/FP029.html#FPQ29OUTP1