4.6 Actuality and Potentiality
The second great distinction we need is the distinction between actuality and potentiality — or, in the language of the tradition, between act and potency. This distinction also goes back to Aristotle1, and it too is of lasting significance.
4.6.1 What Does “Potentiality” Mean?
Imagine an acorn. It is an acorn — but within it lies the potentiality of becoming a mighty oak. It is not yet an oak, but it has the inner disposition to become one.
This “in potentiality” is of the greatest importance in philosophy. For it shows that potentiality is not nothing. It is something entirely real. The acorn really does have the disposition toward the oak within it — and not, say, the disposition toward an elephant or a stone.
And this is the core: potentiality reveals something about the essence of the entity. What an entity can become in potentiality shows what, in essence, it already is.
4.6.2 Three Kinds of Potentiality
But here we need to be more precise. The tradition distinguishes three kinds:
First, passive potentiality: a piece of wood can be made into a chair. But of itself it does not strive to become a chair. The potentiality lies in the material, but the actualization comes from outside.
Second, the active disposition (or, as the tradition says, active potency): the acorn strives from within to become an oak. No carpenter needs to shape it. The direction of its development lies in the acorn itself.
Third, the learnable ability: a human being can learn to play the piano. Before he learns it, he possesses the active disposition for it (as a human being with hands, ears, and understanding). After he has learned it, he possesses a new ability that he did not have before — but one toward which he was disposed by nature. A stone cannot learn to play the piano, not because it lacks lessons, but because it lacks the disposition.
These distinctions are of decisive importance for our question about personhood. For when someone says, “The embryo is not a person because it cannot yet think,” he is confusing the active disposition with the learnable ability, or even with passive potentiality. But the embryo does not merely have the passive potentiality to think one day. It has the active disposition for it: it strives from within toward the unfolding of its capacity to think, to will, and to love.
4.6.3 What This Means for the Embryo
Consider the human embryo. It cannot yet think, speak, or judge. But it possesses the active disposition for all of this. It is directed from within toward developing all of it.
This means the embryo is not first made into a human being. It already is a human being — and merely unfolds what it already is. For the active disposition is the expression of what a being is by its essence, not of what it is yet to become.
“On the way to becoming human” would mean: at some point, at a particular moment, the non-human turns into the human. But when would that be? At the first heartbeat? At the first brain activity? At birth? Any such point is arbitrary, because the development is continuous. There is no moment at which a non-human becomes a human. There is only the moment at which a new human being comes into existence: the fusion of the germ cells. From then on, someone is there.2
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Fußnoten
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Aristotle, Metaphysics (2009), Book IX; Aristotle, Physics (1987), Book III, chs. 1—3. ↩
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Against this thesis the objection of monozygotic multiple formation (identical twins) is sometimes raised: up to about the fourteenth day after fertilization, the cells of the embryo can divide and become identical twins or multiples. From this it is concluded that before this point the embryo cannot yet be an individual being — and therefore cannot be a person. This objection is unfounded. First: the mere possibility of division does not count against actual individuality. What is decisive is not what can happen to a being, but what it is. Second: within the undivided cell cluster the individual cells are not, in fact, totipotent, but parts of a unified biological whole, ordered to one another. Only when they are separated from one another do they gain their independence. The undivided embryo is thus a unity from the very beginning, not a mere aggregate. Third — and this is the decisive point: what happens to the person in multiple formation? The indivisibility of the spiritual person must be granted. But it does not count against personhood from the very beginning. For two possibilities are conceivable: either the original person continues to exist and a new, second person comes into being — or the original person ceases to exist and in its place two new persons come into being. In neither case does it follow that no person was there before the division. It would be arbitrary to conclude from the mere possibility of a later multiple formation that the human being is not a person until this possibility no longer exists. For the person is, as we have seen, first actuality — not the result of a change, but of a coming-into-being. And this coming-into-being takes place with the fusion of the germ cells. ↩