What is the Communication of Idioms?

I. What is “The Communication of Idioms?”

When the phrase communication of idioms refers to Christ, communication should be understood to mean what communicatio means in Latin, and idiom should be understood to mean what ἰδίωμα (idíōma) means in Greek. Therefore, the communication of idioms means the sharing (communication) of properties (idioms). In Christ, the properties of divine nature and human nature are held in common by the divine person of the Son; hence there is a “coming together” of the things proper to each nature in a personal union. A wondrous exchange happens whereby a man has divine attributes, and God has human attributes.

The communication of idioms initially sounds like it should mean something like the transmission of linguistic terms, which is not the original intention behind the phrase, which focused on the communication of such “properties” in Christ Himself. In fact, discussions about the communication of idioms center around what is said and thought, truly or falsely, about Christ. There are three notions that can help in the understanding of how to think and speak correctly about Christ when including elements of both natures:

1. The distinction between formal and material predication;

2. the distinction between concrete and abstract names;

3. reduplication or restricting the consideration to one nature only.

II. Material and Formal predication

The subject of a sentence indicates something or someone in such a way that leaves it open to some determination or speciation by the predicate. For instance, I can say the engineer (subject) dances a waltz (predicate). By using the term engineer to indicate someone, I am not restricted to saying only things about him that are concerned with engineering as such. He does not dance precisely as an engineer, but still the engineer dances. There is no linguistic restriction such that it is only true to say dancers dance, or engineers work mechanisms. The way the scholastics indicate this is by saying the subject of a sentence indicates something materially, broadly, or indeterminately with respect to the predicate that formally determines it. One could say the rail splitter was the 16th president, or the patent clerk discovered the theory of relativity. Those statements, while surprising, are perfectly true, and one might want to put them that way in order to convey something interesting about Lincoln or Einstein.

Of course, the communication of idioms in Christ is a unique case. Only He is one person with two unmixed and unconfused natures. However, the general rules about formal and material predication still apply to Christ. When one says, for instance, the divine person of the Word, what is indicated materially is the entire Christ, including His human nature, even if the human nature is not explicitly signified. One can therefore predicate human properties as formally determinative of the divine person of the Word. For instance, the divine person of the Word was born of Mary, lived on earth, died, and rose again. One can also predicate divine properties of Jesus of Nazareth or other names stemming from His humanity. For example, Jesus created the world and will be our ultimate happiness.

To further help our understanding of the use of language and thought around the communication of idioms, we will look at concrete and abstract names.

III. Concrete and Abstract Names

Since the communication of idioms is the sharing of properties in the one subsisting person of Christ, and not a mixture or confusion of the natures, saying something about Christ that moves from the human to the divine or from the divine to the human must start with a concrete word or phrase indicating Christ. A concrete term is one that indicates nature in a particular, in this case, the particular Christ, like the man Jesus, or God. An abstract term is one that indicates a nature considered in itself and not in a particular, such as humanity or divinity.

Speaking of Christ, we would not say that divinity died or divinity was born of Mary. We would not say humanity was all-powerful. These statements circumvent, as it were, the subsisting concrete person of Christ in which these attributes have a common home. We can say God died, and the Son of Mary is all powerful, indicating things about the particular person of Christ, but we do not attribute human properties to the divine nature itself, or vice versa.

We also would not predicate humanity abstractly to Christ. Christ is not humanity, but He is a man. However, since in God there is not a real distinction between the concrete and abstract, God being perfectly simple, one can say that Christ is the Divinity, which amounts to the same thing as saying Christ is God.

Sometimes, though, even concrete names, through qualifications, can be considered only according to nature, as will be explained presently.

IV. Reduplication

Reduplication is the logical practice of qualifying a statement so as to specify precisely the perspective from which one is viewing a given term. Thus, to follow our examples above: the engineer as an engineer designs physical systems; the engineer as a human is rational. Such reduplication is used in predication related to Christ using the qualifiers as man or as God. Equivalent qualifiers, such as in His humanity, or inasmuch as He is God, could also be used. Reduplication effectively makes the consideration about what is proper to one nature or another of Christ. So, it is not admissible to say that Christ died as God any more than it is admissible to say divinity died. We also would not say that Christ, as man, is omnipresent.

Reduplication can clarify a statement. If someone simply cannot understand how it is true that the carpenter from Galilee has no beginning in time, then one can say that the carpenter from Galilee, as God, has no beginning in time. Though helpful at times, this kind of clarification is not strictly necessary. If such clarifications were always used, there would be a risk of habitually thinking about Christ only as man or as God and not simply of Christ who is man and God, a single subject of actions and attributions.

In other words, it remains true for St. John to say, Jesus—this person whom we have touched and seen—has no beginning in time. Or, as the Fifth Ecumenical Council stated, approving the formula of the Scythian monks: One of the Trinity suffered in the flesh, meaning, Christ suffered in the flesh. To put it another way, we could say, Christ as man suffered. However, if we only understand this statement in terms of the reduplication “as man,” we risk only focusing on Christ’s human nature to the point of treating it as the subject of attribution, as though Christ’s human nature were a subsistent subject (hypostasis or supposit) that suffered. This would amount to a form of Nestorianism. We must remember that the reduplication here is helping us to formulate this truth: the one subject (hypostasis or supposit) of this suffering is indeed the Word, the Word Incarnate; the Word Himself has suffered, in His assumed human nature.

There are statements in which the predicated human term makes it sound like one is referring to the whole person of Christ as such, effectively denying something true about the divine person. For instance, it is false to say that Christ is not divine without qualification, even though Christ has a human nature that is not divine. One can say that Christ, as human, is not divine. Likewise, we would not say simply that Christ is a creature. That would generally be taken to mean something about the personal supposit of Christ. We may say that Christ is a creature as human. It is important to note that some statements should be avoided because of a historical association with error. Statements about Christ being a creature have an Arian savor.

Knowing whether a statement is correct on the basis of the communication of idioms—or even guessing correctly—might be difficult even for a well-catechized person of deep faith, especially regarding statements using reduplication or ambiguous or complicated terms. Occasional difficulty should not be a source of discomfiture for the faithful who would assent to true statements about Christ if such statements were adequately explained and understood.

V. Why is the Communication of Idioms Important?

One can look at the communication of idioms as providing a set of rules we can discern for determining whether certain statements or thoughts about Christ are orthodox or heterodox. Such was the case during the Nestorian controversy, for instance, when the teaching that Mary is the Mother of God was being defended. It is good to have a reasoned account about how to say human things of divine names for Christ and divine things of human names for Christ and what to avoid. Beyond those rules, however, it is also important to realize that predications based on the communication of idioms naturally spring up in faithful Catholic use, in Scripture, creeds, liturgy, and theology, as apt and forceful expressions of who Christ is, what He does, and who does what He does. The communication of idioms lends itself to a way of speaking and thinking about Jesus that reflects the reality of the Incarnation. Acknowledging the communication of idioms in language is a testimony of faith that the Word became flesh and dwelt among us; a studied and principled rejection of statements based on the communication of idioms is a strong indicator of a deficiency of faith. Something of the wonder of the mystery of the Incarnation is conveyed in statements like God died so that sinners may live and The babe who sat in the lap of Mary held her in being.