Almighty and everlasting God, who hast given unto us Thy servants grace by the profession of the true faith, to acknowledge the glory of the eternal Trinity, and, in the power of Thy Divine Majesty, to worship the Unity; we beseech Thee, that by our steadfastness in this same faith, we may evermore be defended from all adversities. Through Christ our Lord. Amen.
One of the difficult to understand, yet vital, aspects of Catholic theology is to correctly identify what is meant by the term “person” (persona). In our experience of created reality, we possess such a strong intuitive knowledge of personhood, yet the ability to express the definition of such seemingly escapes us. To strengthen the difficulty, we are awash with psychological notions of personhood, rooted in intellection and identity, rather than the clearly defined metaphysical notions of personhood that Catholic theology has developed and defined rigorously. Therefore, such a simple term as “person” ought not to be glossed over quickly.
There are many so called “theologians” today who are rooted more in Descartes, Freud, and Jung on this question of personhood, rather than that sense which the Catholic faith holds so stringently to. The height of theological error and pernicious heresy is wrought by those who err on this point; therefore, the Catholic ought to hold fast to this definition of person as he would his very life, being most essential to the defense and propagation of our faith. This error brings forth ridicule on the Catholic faith by our Mohammedan opponents.
There is a two-fold error brought about by this essential corruption of the faith (there are examples too numerous to number). First, they err in Christology. For, if person is a locus of intellection and willing, then Christ must have a single will and mind, which results in the heresy of the Apollinarians (and the children of this heresy, such as Monothelitism and so called “Neo-Apollinarianism”). Second, they err in their Trinitarian Theology, for, on the supposition above, the Trinity will be a mere moral communion of individual loci of intellection and will, falling into the heresy of the Tritheists (and the children of this heresy, such as the Social Trinitarians).
Now that introductory matters have been dealt with, what, then, is a person?
To do such, I will set forth a process of deduction from the universal to particular, adding detail at each step until we arrive at our definition of person (persona).
Fundamentally, a person must be a “being” (for, if not, it would be non-being, and therefore would be “nothing,” which would be absurd).
Being can either be a “substance” (being in itself) or an “accident” (being in another). Clearly, personhood is not accidental to a certain thing, therefore, it is a substance.
Substance can either be “prime substance” (concrete and individual substance), or “secondary substance” (abstract and general substance). Self-evidently, a person is something which is concrete and individual, incommunicable to any other.
Here, we have arrived at what St. Thomas will term a hypostasis, i.e., an individual substance. Yet, many things may be a hypostasis, yet, not a person. For, hands, feet, and the like, are “individual substances.” Therefore, we can add a further note, that of integrity or completeness.
Now, we have arrived at a definition of an “integral and individual substance,” yet a difficulty arises. For, Christ’s humanity is said to be an “integral and individual substance,” yet we do not say that Christ’s humanity is a person. Therefore, we can add another note that it is not only integral, but not a part of another, whole in itself. Therefore, the “plain” definition of Pohle arrises, “an individual substance, separate and distinct from all other substances of the same kind, possessing itself and all the parts, attributes, and energies which are in it.”
A Further difficulty arrises, there are many things which are “integral and individual substances, whole in itself,” that are not persons, such as a rock, book, pair of scissors, cigar, and the like, yet are not persons. Therefore, we add the note of “of a rational nature.” The nature which is possessed by the Person is a rational one.
Here, the common error outlined above arises. It is VERY important to note that there is a STRONG difference between the “possession of a rational nature” and adding “consciousness/will/intellectual activity” as a note of personhood. The person is the ego which is the possessor and principle of such intellectual activity and not the intellectual activity itself. A natural example will suffice to understand the problem present with the confusion. For, let’s consider the case of a newly conceived child, such ought to be regarded by all as a “person” (only the defenders of infanticide differ in this regard). Yet, all agree that such is devoid of consciousness. By what grounds can he be referred to as a “person?” He has not yet reached the age of reason. With our definition of “person” he certainly can be referred to as a “person,” for he is a possessor of a soul which has rational faculties and can be said to be the principle of a rational nature, and, in a real sense, a possessor of rational acts in habitu, non in usu (in habit, not in use), from which will arise self-consciousness and volitional activity in actu (in actuality). The person is that root of the operation of self-consciousness and will, not the self-consciousness and will itself.
This example of an error clears up the true relationship between nature and person, thus clarifying Catholic Trinitarian/Christological thought. For, the person is a possessor of the nature. This is self evident in our language about personality, for, we do not say that “I am a human nature,” but, “I have a human nature.” The “I” (person) possesses human nature. The person operates through the nature and is the principle of operation in the nature. Thus, the operations of the nature (including will and intellection) is not the person, but is referred to the person as its subject. Thus, the operations of the Divinity and Humanity of Christ are referred to the person of the Son as its subject and principle, while yet, there are two wills, intellections, etc. Further, there is one will of the Trinity, yet such can be predicated to three subjects, the Father, Son, and Holy Ghost.
C.f., Joseph Pohle and Arthur Preuss, The Divine Trinity: A Dogmatic Treatise, Dogmatic Theology (St. Louis, MO: B. Herder, 1915), 220–228.