Although Aquinas’s Treatise on Human Nature extends from question 75 through to question 102, one often finds commentaries on this treatise curtailed at question 89. This marks what might be seen as a boundary between Aquinas’s “philosophical” treatment of man and his scriptural or theological treatment. Modern tastes might see the first part of the treatise as having more lasting importance that the second, but Aquinas probably thought of this first part as preparatory for the second part. Such neglect of the second part is regrettable since even if one were to disagree with the conclusion of the master, one would be very foolish to neglect his method.
Aquinas breaks this section of the treatise into four parts. In the first three questions, Ia.q90-2 he considers the origins of human beings, in Ia.q93 he considers the goal of the production of humans, in Ia.q94-101 he will consider their status and condition when they were first produced and in Ia.q102 he will consider their location when they were first produced.
Why this Question Matters
As the human being is a composition of body and soul as form and matter, the first line of enquiry that Aquinas takes about the coming to be of humans is to ask about the origin of the soul. He will turn to the production of the body in the next question and will pay particular attention to the initial production of woman in the question after that.
The Thread of the Argument
A1: The first article deals with the question of whether the human soul originates as part of God’s substance; one might read Genesis 2:7, wherein God breathes life into Adam, as supporting this point of view. But as Aquinas points out, this is a claim that is, on the face of it, implausible. At the very least one must observe that the human soul is in potentiality with respect to certain things; something that is not true of God’s substance. Clearly Aquinas, in raising this strange idea, is dealing with an opinion current in his day and wishes to squash it with no further ado.
Aquinas identifies the erroneous opinion as arising from two ancient positions. Firstly those who considered that all things in the world are bodies would naturally be drawn to an opinion that the soul must be a body that is derived from the body of God. Secondly, those who realised that immaterial substance exists but did not progress beyond the idea that the form of God provided the form of everything (a sort of world soul) would also hold this opinion. The discussion of Ia.q3 demolished these positions and therefore such an idea of the origin of the human soul vanishes as well.
In the reply to the first objection, one should note Aquinas interpreting the breathing of Adam’s soul as figurative language for the production of the soul.
A2: When we think about a material object we can think of the object in terms of various compositions: matter and form, actuality and potentiality, essence and existence. For such an object we think of its potentiality in terms of the matter out of which it is made and of its actuality in terms of the form that makes it what it is. Similarly we can think of the form of the object as that which gives being to the object. If we turn to something like the human soul, then we might be tempted to transfer this reasoning without change and think of the human soul as being made out of some sort of spiritual matter, made to be what it is by a spiritual form suited to such spiritual matter. This latter theory, often associated with figures such as St. Bonaventure, is rejected by Aquinas. As we have seen in Ia.q75 & q76, Aquinas considers the human soul to be a subsistent form that informs the human body; the composition of actuality and potentiality in the soul is not a composite of matter and form, rather the soul is a form that informs the body. A subsistent form is not made of anything; it either subsists entirely on its own (in the case of the angels) or it is what makes something what it is (in the case of the human being).
So whereas we can rightly think of material objects coming to be by being made out of something that previously exists, we cannot transfer this reasoning to immaterial subsistent forms such as the soul. Such forms have to be created out of nothing. Something material comes to be by its form being received into an already existing material object that is in potentiality to receive the new form. This cannot happen for the human soul (and for angels); there simply is nothing pre-existing to receive anything.
A3: One might ask whether the human soul is created directly by God or whether some form of intermediation occurs. The human soul lies at the lowest point of the hierarchy of immaterial being and therefore one might think that the beings higher up the hierarchy bear some of the labour of creation.
Aquinas rejects this as contrary to the faith: God alone is able to create ex nihilo. If angels were involved as intermediaries in the creation of the human soul then they would be making the soul out of something received from higher in the hierarchy. This would no longer be a genuine creation but a making out of something pre-existing.
A4: Was the soul of Adam created before his body and are the souls of subsequent human beings created before their corresponding bodies? Throughout history, there have been those that claim the soul is created first and then fitted into its body. Most famously Origen held this view, believing souls to be metaphysically complete in themselves and then subsequently tied to human bodies. As Aquinas points out, even St. Augustine can be interpreted as supporting some form of this view.
Aquinas argues that God “instituted the first things in a state of natural perfection” and that as the soul is naturally the form of the body then the soul is not created before, and in isolation from, the body. He handles the obvious objection, that the soul is subsistent and remains in being after the death of the body, by observing that the death of the body is a defect of the body, a defect that is not supposed to exist when the soul is created.
- The human soul is created immediately by God out of nothing.
- The human soul does not pre-exist the body as this would create the soul in a state lacking its natural perfection.
- In the fourth article, Aquinas puts a lot of weight on the principle that God creates things in a natural state of perfection and that the soul, although subsistent in its own right, requires a body to be in such a state of perfection. The state of the soul after death and before the general resurrection is in a strange state of tension; naturally able to subsist, but in a state not natural to it.
- The fourth article argues that the soul does not pre-exist the body, but does not touch upon the question of whether the body pre-exists the soul! Aquinas took the view that matter could only receive a form if it was in a state suitable to that reception. On the basis of the biological understanding of that period, such a reception would not occur at the point of biological conception; instead there would be a succession of vegetative, animative and finally rational souls in the development of the embryo. Modern biological understanding has shown that the developmental course is set as soon as the embryo’s DNA is established; put in medieval terms, such a newly conceived embryo can be receptive of its rational form even if many of its powers are obstructed until bodily development proceeds. The Church has never given a doctrinal definition of the point at which the human soul is infused, but most modern Christian philosophers would now argue that it is at the point of biological conception.