Friday, 3 December 2010

Question 33 - The Person of the Father


Aquinas has dealt with the Persons of the Trinity in general in Questions 29-32 and will return to a more detailed comparison of the Persons in Questions 39-43. In the meantime, as the next step in this subsection, he looks at each individual Person. He devotes one question to the Person of the Father (Question 33), two to the Person of the Son (Questions 34-35) and three to the Person of the Holy Spirit (Questions 36-38).

Why this Question Matters.

Devoting questions to each individual Person of the Trinity allows Aquinas to go into greater depth concerning questions particular to each Person. For the Father, Aquinas introduces the idea that He is the principle of the other Persons of the Trinity and discusses and disposes of objections to the notions of the Father introduced in the previous question.

The Thread of the Argument

A1: One of the ancient Trinitarian errors that Aquinas wishes to avoid in his account of the Trinity is that of subordinationism. This error is a collection of ideas that suggests that the Persons of the Trinity are not co-equal: one may be prior to another; one may be cause of another; one may be superior to another; with many variations on this theme. However, we do wish to acknowledge that there is some sort of structure, of ordering, within the Trinity. In this article, Aquinas introduces the idea that the Father is the principle of the Son and of the Holy Spirit and he explains the sense in which the term “principle” can be used in an orthodox way.

Aquinas’s argument is very brief: used in this theological sense, a principle is simply that from which something proceeds. As the Son and the Spirit proceed from the Father, we can truly say that the Father is principle of the Son and the Spirit. The bulk of the article is taken up in answering objections that are designed to hone the precise meaning of what Aquinas has stated. Maintaining Augustine’s teaching that “the Father is the principle of the whole divinity”, the key is that “principle” used in this sense does not imply “inferior” or “posterior” or any other terms that imply subordination.

The first objection is that Aristotle teaches that a principle is the same as a cause and that we do not call the Father a cause of the Son. Aquinas replies that the Greek theologians use the words we translate as “cause” and “principle” interchangeably but that Latin theologians use the corresponding Latin terms more precisely. For the latter a principle is more general than a cause. As more general terms are more appropriate to God (Question 13, Article 2) it is appropriate to use the term “principle” of God. With this distinction we can see that “cause” implies a dependence of one thing upon another but that “principle” does not.

Another sense of the word “principle” suggests that something is the principle of something else if it is responsible for the beginning of that thing. This cannot be the case with the Father as principle of the Son as the Son has no “beginning”. Again, there is a difference in terminology between Greek and Latin theologians: this sense is not allowed in Latin theology. The Latin theologians are willing to go so far as saying that the Father is the “author” (Latin auctoritas) of the Son, but insist that this term does not imply any subordination.

Finally, the term “principle” is related etymologically to the term “priority”; this would seem to be a problem. However, Aquinas insists that the signification of “principle” here relates to priority in the sense of origin and not in the sense of prior/posterior.

A2: Scripture applies the term “Father” to the first Person of the Trinity. Aquinas is happy to build on this by asserting that proper names signify that which distinguishes an individual from other individuals. Since the Father is distinguished from the other Persons of the Trinity by his paternity, the proper name of the first Person is “Father” as this is the name that signifies that paternity.

Although the term “Father” is a strictly relational one as far as we are concerned, this is no objection to applying it to the first Person of the Trinity on the basis that it is not a term pointing to an individual substance, because relations in God are subsistent. Similarly, although we speak metaphorically of a word being begotten by its “father”, when we apply the terms to the Trinity they are applied properly and not metaphorically.

The final objection suggests that the notion of “generation” and therefore of “father” is derived from its application to creatures and subsequently applied to God. This would contradict the proper application of terms to God that are said primarily of God and subsequently of creatures by analogy. Aquinas denies this order of priority, teaching that the more perfect notion of generation is where the thing generated has numerically the same form as that generating (i.e. God generating the Son) as opposed to simply the same species as that generating (i.e. as in creatures).

A3: When we pray the Lord’s Prayer, we pray to the entire Trinity, yet we pray to “Our Father”. It would seem that the term “father” can apply both to the individual Person of the Father and to the whole Trinity. Which of these applications really has priority? One might argue that a common term (i.e. applied to the whole Trinity) has precedence over a personal term (i.e. applied to one Person of the Trinity). Similarly, one might argue that there is no priority of one application over the other; the term applied to the relation between the Father and the Son is applied on the same basis as it is applied to the relationship between the Father (as God the whole Trinity) and us creatures.

In a move that might remind us of how analogical predication works, Aquinas claims that priority is to be given to names applied in situations where the whole meaning of the name is exhibited in its use rather than where it is exhibited in a certain respect. We might call a man a “lion” because of his character, but this meaning is secondary to the application of the term to the large feline animal. In the case of the terms “father” and “son” it is clear from previous arguments (Question 27, article 2; Question 28, article 4) that these are most perfectly found in the relation between the Divine Persons. Aquinas brings a number of scriptural arguments to bear to prove that the term applied to the relationship between God and creatures is derivative of this Trinitarian application.

In reply to the objections, Aquinas points out that although common names do take priority over proper names, the argument that he has just made shows that common names associated with a relation to creatures are posterior to proper names associated with relations between the Divine Persons. This mirrors the fact that the procession of creatures from the mind of God is posterior to the procession of the Word through which those creatures are created.

A4: In Question 32, Aquinas introduced the notions of the Persons of the Trinity. In this article, he concentrates on the notion that the Father is unbegotten. Connecting this idea with that of principle introduced in Article 1, he observes that the Father is unbegotten in the sense that He is a principle-not-from-a-principle just as the Son is begotten of the Father in the sense that He is a principle-from-a-principle.

There are still a number of problems with the term “unbegotten” and the corresponding property of innascibility that have to be addressed. The first is that these terms appear only to deny something of the Father rather than posit a positive property. But Aquinas replies that first things and simple things are known through negation, so that this really is no problem.

Trickier is the problem that a term like “unbegotten” can either be taken as a privation or a negation. The former is ruled out because privations correspond to lacks of perfection and this cannot be said of God. However, if “unbegotten” is taken as a negation then we can surely apply it to the Spirit who, although He proceeds, is not begotten. This would mean that the term is not proper to the Father. Aquinas answers that this reasoning depends on too shallow an analysis of “privation”. There are some uses of the term “privation” which do not imply imperfection: a mole is blind whereas other animals are not but this does not imply that a mole is an imperfect mole as it has no need of sight for its perfection. In this sort of sense, it is no problem to consider being unbegotten to be a privation. However, this still leaves the problem that the Spirit might be considered unbegotten. This may be addressed in two ways: the term “unbegotten” may either be associated with the idea of not-from-a-principle or with the idea of not being from another in any way (and not just by generation). Either of these approaches makes the term proper to the Father.

Another problem is that “unbegotten” is not a relational term and therefore if it is applied to the Trinity it must denote the substance rather than a particular Person. This would have some difficult consequences. Aquinas identifies two senses of the term “unbegotten”, one of which can be taken as referring to the substance of God and whose application simply implies the uncreatedness of the Divine substance. The other sense of the term can be taken relationally, as it gains its reference from the term “begotten” which is relational. So, for example, the Father and the Son are distinct because a particular relation holds for one but not for the other.

The Father is not begotten, but also He does not proceed, so why is non-procession not a notion of the Father? The point here is that the Father’s not-being-from-another is fully described by reference to the Father-Son relation in which the Son is begotten and the Father is not. The procession of the Spirit presupposes the generation of the Word, so once we have denied being begotten of the Father, it follows that the Father does not proceed.

Handy Concepts

  • The Father is principle-not-from-a-principle in the Trinity.
  • Orthodox Christian theology avoids any idea of subordination amongst the Persons of the Trinity. Although the Father is principle-not-from-a-principle, this does not make Him superior to the other Persons of the Trinity.
  • Although the name “Father” is proper to the first Person of the Trinity, it is also used to refer to the entire Trinity as when we pray to the Father in the Lord’s Prayer.

Thursday, 2 December 2010

Question 32 - Our Knowledge of the Divine Persons

Why this Question Matters.

Aquinas believes that the fact that God is Trinity is purely a truth of revelation indemonstrable by human reason. However, although indemonstrable it is not unreasonable, as he has shown in previous questions. So far, we have seen how a metaphysical picture of God as Trinity can be built up consistent with (and possibly implied by) the data of revelation. This still leaves open questions about what we can know of the underlying reality of God as Trinity (the question of epistemology rather than ontology). In this question, Aquinas introduces facts about God that allow us conceptual access to the Persons of the Trinity; the notions in God that allow us to characterize and distinguish between the Persons.

The Thread of the Argument

A1: Aquinas has shown (in question 12) that our natural knowledge of God (i.e. the things that we can know about God in the absence of revelation) is derived purely from our knowledge of creatures. This means that our natural knowledge of God is restricted to what we can know of Him as causing the being of creatures. However, God’s creative power is common to the entire Trinity and is therefore associated with His essence rather than with the distinction of the Persons. Hence, our natural knowledge of God does not extend to a demonstrable knowledge of the Persons.

Aquinas goes further, saying that attempts to prove the Trinity of Persons are actually damaging to the faith. On the one hand, truths that are purely of the faith by their very nature surpass and excel human reason; to bring them down to our level is to undermine their dignity. On the other hand, attempts to prove such truths of faith (which are bound to have metaphysical holes in them) bring the faith into disrepute amongst unbelievers because it would appear to the latter that Christians base their beliefs on nonsense. Truths of the faith, such as the Trinity of Persons in God, should be received only through authority; theologians should concentrate their arguments on showing that such faith is not metaphysically impossible.

In the replies to the objections, Aquinas gives a forward reference (Question 39) to the idea of the appropriations: some attributes of God which are really associated with His essence can be appropriated to one of the Persons of the Trinity with which this attribute has a special affinity. We appropriate God’s power to the Father, His wisdom to the Son and His goodness to the Holy Spirit, for example. Aquinas is willing to admit that philosophers are able to infer the existence of such essential properties amenable to appropriation to the Persons.

In the reply to the second objection, Aquinas discusses the nature of explanation. In doing so he gives a nice illustration of a sophistication in medieval science that some may find surprising. He points out that an “explanation” can, on the one hand, have the nature of a proof or, on the other hand, it can simply provide a consistent description of matters of fact and that there may be other equally valid consistent descriptions. As an illustration of the former, Aquinas claims that the uniform motion of the celestial bodies is amenable to proof. For the latter, he describes the fact that although epicycles and eccentrics give a consistent explanation of the observed behaviour of astronomical objects, some other explanation may be superior.

A2: Aquinas now introduces the twin ideas of the Properties and the Notions in God. Simply put, the properties in God are what belong to each Person, as a Person, which allow them to be distinguished one from another; the notions are these distinguished characteristics inasmuch as they are known by us and allow us to distinguish the Persons (with a technical caveat concerning the common spiration of the Holy Spirit by the Father and the Son). This article considers whether it makes sense to posit notions (and therefore properties) in God. The usual objections can be made: scripture does not talk explicitly of such things therefore neither should we; such ideas confuse the already complex distinction between essence and personhood in God; one shouldn’t start to posit such things about a purely simple being. Despite the objections, Aquinas is able to rally patristic support in favour of the idea of the properties and notions: we simply do recognize that there are paternal, filial and processional properties and that we can know about them.

In the medieval period there were a number of solutions to this question offered by a variety of theologians. The “classical” position had been put forward in the standard textbook of the time by Peter Lombard. This stated that there are five such notions in God: the Father’s unbegottenness (or innascibility) and paternity; the Son’s filiation; the procession of the Spirit and the spiration of the Spirit common to the Father and the Son. Aquinas begins his answer by introducing the figure of Praepositonius of Cremona (Chancellor of the University of Paris at the start of the thirteenth century) as representative of those theologians denying such notions in God. Praepositonius identified statements such as “the Father distinguishes Himself from the Son through paternity” as simply being the equivalent of “the Father is the Father”. Statements such as the former are simply ways of speaking that actually say no more than that the Persons are distinct and that God is one.

Aquinas will have none of this! He recalls that we name in the way that we understand and that we understand things as concrete realities (named by concrete words) or as principles or forms of such things (described by abstract words). Applying our use of language to God does not destroy Divine simplicity: we can still apply abstract names when we talk of God’s essence and concrete names when we talk of the subsisting relations. If we were unable to do this, then we would be completely unarmed to argue against Trinitarian heretics: we need to be able to talk of God’s substance as a “what”; of the Persons as a “who”; and of the relations as a “that by which”. Within the Father there is no real difference between what He is, who He is and that through which He is; but in order to understand and describe Him we must be able to perceive and distinguish these three. A further consideration is that if we were unable to distinguish notions in such a way, we would not be able to distinguish between the two relations that the Father has with the Son and the Spirit respectively. However, it’s important to note that the filiation and the spiration are not distinct realities within the Father so the corresponding notions do not divide the Father but simply distinguish His relations.

A3: Having introduced the notions in the previous article, Aquinas now sets about defending the “classical” list. In order to account for the notions, Aquinas claims that Divine Persons are multiplied by their origin and that this can arise in two ways: by being source of another or by being from another. The Father is known by being not from another, the notion of innascibility (or unbegottenness). He is also known by the facts that the Son and the Spirit are from Him and these give us the notions of Paternity and Common Spiration. Similarly the Son is known by His Filiation and also by the Common Spiration and the Spirit is known by the Procession. There are thus five notions in God, only four of which are relations (innascibility is not relational, for which, see Question 33, Article 4). Similarly, only four of the notions are properties (as the common spiration is not a personal property). Aquinas completes his account with the rather obscure distinction between “notions of persons” and “personal notions” (which will be explained further in Question 40, Article 1) to claim that three of the notions are personal (Paternity, Filiation and Procession) whereas the other two are simply notions of persons.

A4: It might have seemed so far that Aquinas defends the notions in God as being of the Faith itself, especially in the light of his argument in favour of the notions based on the need to be able to refute heretics. But this would leave Aquinas in a difficult position: many distinguished theologians of the recent past disagreed with the account that Aquinas gives. Does this mean that Aquinas considers them all heretics?

In order to address this problem, Aquinas makes a distinction. One can identify those things that pertain directly to faith as revealed to us. For example, that God is both one and three. To deny any of these truths would be to fall immediately into heresy by the very nature of the denial. On the other hand, there are matters that pertain indirectly to the faith rather than directly. For example, a denial that Samuel was the son of Elkanah is not a direct denial of a truth of the faith, but the denial implies the proposition that sacred scripture errs in places which is a direct denial of the faith. In this case, the inference is pretty straightforward but in many cases the chain of reasoning from a particular proposition to a direct denial of the faith may be highly complex (and, indeed, inaccessible to many people). If this is so, then one cannot accuse of heresy those who hold such mistaken beliefs because the proof of their erroneous nature was not available to them.

Handy Concepts

  • Our knowledge of God, derived from created causes, reveals the essence of God, but not the Persons as created causes are actions of the entire Trinity.
  • The notions are distinct characteristics of the Divine Persons by which we can distinguish between them. We can go on to distinguish notional acts (where we think of the Divine Nature from the point of view of its relations) and essential acts (where we think of the Divine Nature absolutely).
  • Cajetan identified that “This question does not concern the reality considered absolutely in itself, but the reality insofar as it is described and apprehended by us”.
  • One cannot accuse of heresy those who were not in a position to be able to comprehend that a particular position implies a denial of the faith.


  • Relations, notions and properties are all the same reality, differing from one another only conceptually. This distinction is not available to reason alone but is itself guided by revelation.

Wednesday, 17 November 2010

Question 31 - Terms Referring to Unity and Plurality in God

Why this Question Matters.

Aquinas has established that the persons of the Trinity are subsisting relations, the relations being derived from the scriptural data concerning processions. He now moves on to discuss what we can say about various aspects of the Trinity. The character and focus of this question may, at first reading, appear to be slightly odd. However, it reflects the keen interest that medieval philosophy took in the functioning of language and in the relationship between language and the traditional areas of philosophy. (In these concerns, medieval philosophy shows a fascinating similarity to many aspects of the linguistic philosophy of the twentieth century). The choice of subjects for the articles of this question reflects some of the most important and lasting controversies in the Middle Ages about the use of language when applied to God. Aquinas’s immediate concern in this question is revealed in the body of the second article: “heresy arises from words that are used incorrectly” (quoting St. Jerome) and “There is no other place where error is more dangerous, where questions are asked more rigorously, or where anything more fruitful is found” (quoting St. Augustine). So then, what can we say about God as Trinity and what must we avoid saying?

The Thread of the Argument

A1: Aquinas has shown that we can attribute a plurality of persons to God; in this article he demonstrates that we can be more specific and attribute the name “Trinity” to this plurality of persons. The argument is very straightforward: the name “Trinity” simply signifies determinately what the word “plurality” signifies indeterminately. The bulk of the article is devoted to answering a number of linguistic objections to this attribution.

As an example, the first objection suggests that names must either signify the substance of God or a relation within God. The word “Trinity”, taken as a name, can’t signify the substance because this would attribute the substance of God individually to each person (leading to tri-theism). However it can’t signify a particular one of the relations because it clearly is not a referential word. Although Aquinas admits that etymologically the word “Trinity” would appear to refer to the single essence of the three persons, as it is used in the context of God it refers to the number of persons in the single essence. The objection has set up a false dichotomy.

A2: The question of whether we may say that the “Son is other than the Father” had a lengthy pedigree in medieval times; it almost became a standard scholastic exercise. The fundamental dichotomy is that we want to be able to say it in order to distinguish between these two persons of the Trinity, but we must beware of the possibility of it expressing the idea that the Father and the Son are different in the sense of being substantially different. Aquinas uses this background to chart a terminological course between the Arian error of dividing the substance of God and the Sabellian error of conflating the persons. In thinking about Arianism, Aquinas teaches that we must avoid words like “diverse”, “different”, “separate”, “divided”, “disparate”, “alien” or “discrepant” because all of these are too suggestive of various erroneous positions. However, we can use the word “distinct” especially if we note that it is referring to the relations. He comes up with a similar list when considering Sabellianism. Essentially, Aquinas is attempting to build a list of allowable words and their definitions in order to avoid the sort of misunderstandings that arose frequently in the past.

In addition Aquinas applies the principle of expositio reverentialis by saying that when we come across an orthodox authority who uses language imprecisely we must recognize that we have to understand that language in an informal sense, substituting correct formal terminology as we read.

Having considered such terminology, Aquinas concludes that it is reasonable to say that the Son is other than (alius) the Father because the word implies only a distinction of supposita rather than of substance. It’s worth noting that in the reply to the fourth objection Aquinas is so precise as to say that alius (i.e. the masculine grammatical gender) refers to the supposita and therefore acceptable whereas aliud (i.e. the neuter grammatical gender) refers to the common essence and therefore cannot be used.

A3: The next article tackles the linguistic question of how the word “alone” can be used when talking about God’s essence. In order to address this question Aquinas introduces the grammatical ideas of categorematic and syncategorematic terms: a term is categorematic if it can stand as the subject or predicate of a proposition. So in the phrase “a white elephant” the term “white” (acting as a predicate) signifies something absolutely with respect to the subject “elephant”. On the other hand, a syncategorematic term is one that is not categorematic. Words like “of” and “and”, “all” or “none” are usually (always?) syncategorematic. A word like “alone” can act in both ways: compare “Socrates is alone” with “Socrates alone is writing”: in the first proposition “alone” is functioning as a predicate describing the fact that Socrates is on his own. In the second proposition Socrates need not be alone; we simply learn that Socrates is the only one writing.

Aquinas observes that we can use “alone” syncategorematically when speaking of God’s essence (“God alone is eternal”, for example) but not categorematically (“God is alone” for example). To do the latter would contradict the conclusion reached in the previous article.

A4: Having dealt with the question of how the word “alone” may be used in propositions about the divine substance, Aquinas now asks the same question of propositions about the divine persons. If we take the proposition “The Father alone is God” then we can immediately see that a syncategorematic reading does not work as it attributes solitariness to the Father (against the teaching of Article 2). Even when we read it syncategorematically, we have to be aware of different possible meanings. The correct meaning is equivalent to “He, being the only one who is Father, is God”. Aquinas points out that this is such a subtle use of grammar that it is dangerous and that such phrases should not be left to stand on their own but should have explanations attached. Aquinas provides precisely such explanations for a number of common examples in the replies to the objections.

Handy Concepts

  • Aquinas is guided again in this question by the need to sail between the twin Trinitarian errors of Arianism and Sabellianism.
  • Aquinas practises and preaches the doctrine of “expositio reverentialis”: we must read orthodox authorities with sympathy and reverence, realizing that although the terminology may be misleading, or the ideas insufficiently developed, the kernel of the ideas presented is correct and what the authority writes should be built upon rather than demolished.
  • A term is categorematic if it can stand as the subject or predicate of a proposition. Otherwise it is syncategorematic. Words such as “alone” can only be used syncategorematically of the substance and persons of God and even then should be used with care and glossed precisely.


  • Why does Aquinas not refer to the idea of transcendental multiplicity in the first article?
  • This question may appear to be reserved only to grammar nerds, but the underlying principle that sloppy use of language can make a complete hash of theology is a vitally important one.

Monday, 15 November 2010

Question 30 - The Plurality of Divine Persons

Why this Question Matters.

God is one and yet God is three. In this simple statement of Trinitarian faith lays one of the greatest mysteries of Christianity. That it is true is a matter of faith and, Aquinas believes, it cannot be demonstrated on purely metaphysical grounds. Still, we can ask whether it can be considered coherent. Aquinas has identified that scripture reveals to us that there are real subsisting relations within the Godhead and that we can identify these with the “persons” identified in the creedal statements of the Church. Aquinas now focuses on the question of plurality in the Godhead with respect to the persons: is there plurality? How many persons are there in the Godhead? In what sense can we even think about using number when it comes to the persons of the Godhead?

The Thread of the Argument

A1: In the light of the Christian teaching on the unity and simplicity of God, the first question to ask is whether it makes sense to talk about a plurality of persons in God. Of course the Christian Tradition, here illustrated by the Athanasian Creed, insists upon such a plurality and Aquinas aligns his teaching with this. As the notion of “person” corresponds to a relation subsisting as a reality in the Godhead and as there are a plurality of such relations, then it makes sense to talk of a plurality of persons in God.

The reply to the first objection sees Aquinas continuing his explanation of the possibilities for confusion in the Greek and Latin terminology. The second objection asks why, when the absolute properties of God (such as goodness and wisdom) do not lead to differentiation, relations do lead to such distinctions. Aquinas recalls the fundamental difference between absolute and relative properties: the very being of relations is founded in their pointing to something else; they exist in opposition. It is this that creates the multiplicity from relations. Continuing this theme, for the third objection Aquinas points out that a plurality of absolute things (such as goodness, wisdom) does not create plurality in God because of His simplicity. But relations, because of their pointing-to-the-other, do not create the type of composition of thing-and-property that would contradict simplicity. Finally number, by its very definition, would seem to create parts-within-a-whole. Aquinas replies that, at the very least, we can attribute number as an intellectual construct to God because such a construct exists in the intellect rather than in the thing itself. He postpones until Question 42 Article 4 a discussion of why number existing in things (as when we count parts of a whole) does not pose a challenge when we apply it to the Trinity.

A2: Having accepted that we can reasonably talk about persons in the Godhead, we must continue the enquiry of Question 27 Article 5 and Question 28 Article 4 and check that Aquinas’s Trinitarian theory gives us the “right” number of persons. Aquinas argues that the real distinctions among the persons arise from their being in relational opposition to one another; therefore all he has to do is to count the genuine relation oppositions. The technical difficulty arises from the doctrine that the Holy Spirit proceeds from the Father and the Son (the famous filioque clause of the creed). Unless care is taken over the relational opposites associated with the Holy Spirit, there will be some double counting.

The relations to sort out are the spiration and the procession (the latter in the sense specialized to the Holy Spirit). First Aquinas points out that procession cannot be associated with the Father and/or the Son, since if this were so the relations of paternity and sonship (based on intellectual procession) would be founded on the procession of the will. Therefore procession is associated with the Holy Spirit and spiration is associated with both the Father and the Son. In the reply to the first objection, Aquinas goes a little bit further and explains that whilst paternity, filiation and procession are personal properties (i.e. they constitute the persons), spiration is not as it neither belongs to a single person nor constitutes a single person.

A3: When we talk about plurality or number in the Godhead we are faced with one of the central mysteries of the Trinity: how can there be just one God (who is absolutely simple) and yet there be these three “persons” in the Godhead. So far, we may have been unconsciously assuming that we apply the concept of number univocally to God and to creatures; but is this valid? What does it mean to apply number to God? Do numerical terms imply some reality in God?

Aquinas observes that the notion of plurality arises in two ways. On the one hand, material things can be divided into subsets and from this we associate number with quantity. On the other hand there is a transcendental notion of plurality that arises from dividing being into the one and the many. This latter is the only sort of plurality that makes sense for immaterial things. Aquinas claims that previous authors have become muddled on this issue by attempting to apply the first notion of number to God. Aquinas rejects this line of thinking, suggesting that if it is followed one can only make sense of numerical claims about God in terms of metaphor.

Aquinas therefore considers number as applied to the Godhead in terms of the transcendental notions of unity and multiplicity. Aquinas has already applied the transcendental notion of unity (convertible with being) to God’s essence in Question 11 Article 1: When we say that God is one, we are positively affirming that His being is an undivided reality. Here Aquinas applies transcendental multiplicity to the Godhead: what this affirms is that each person is undivided and that each person is not some other person. Put in this way, Aquinas claims that we can then affirm number to the Godhead as a reality and not just as a metaphor or simply as an intellectual construct. Moreover, as Aquinas lays out in his reply to the third objection, unity does not exclude multiplicity but rather excludes division. Similarly, multiplicity does not exclude unity but rather division between the realities out of which the multiplicity is formed.

A4: The final article in this question is a somewhat technical exploration of how the notion of “person” can be considered common to the three persons. That there might be a problem is explored in the objections: for example, only essence is common to the three persons, therefore personhood cannot be common to them. Similarly, if “person” is common to the three then it is either a real or conceptual commonality. If it is only a conceptual commonality then there is really only one person; if it is a real commonality then this would seem to set up “person” as being a universal with God possessing particularity, or genus and species, with respect to this universal (see Question 3 Article 5).

Aquinas points out that when we talk about creatures such as men, the name “person” is common to them, but it is a different sort of commonality than that implied by saying that they share the same essence. It is not a real commonality, but the type of commonality that it is has been something over which various authors have disagreed. Aquinas argues that this commonality is a commonality of concept, pointing towards the notion of an indeterminate individual (such as we refer to when we say “a man” without any particular man in mind). Even with this vagueness, in the example of “a man”, we point towards a common nature, together with a particular mode of existing as a per se individual. Now when we use the term “person” (as opposed to “a man”) things are slightly different: we are pointing towards a reality that subsists in a particular nature. This is what is conceptually common to all of the divine persons.

In answer to the objection against conceptual commonality, Aquinas points out that even when we consider creatures, commonality of personhood does not set up commonality of genus or species, so the objection fails. Moreover, things are simply different when we consider the divine: the persons share a common being whereas creatures particularizing a universal have different beings.

Handy Concepts

  • “Persons” in the Godhead correspond to subsisting relations and therefore we can talk about a plurality of such persons.
  • Spiration is a real relation in the Godhead but does not belong to or constitute a person; therefore the four real relations in the Godhead correspond to three persons.
  • In considering number and plurality to arise out of the division of being into the one and the many, Aquinas is following Aristotle’s Metaphysics.
  • The discussion of number as applied to the Godhead had rumbled on for many years during the middle ages. A good discussion of the background to Aquinas’s treatment can be found in Chapter 7 of Emery’s “The Trinitarian Theology of St. Thomas Aquinas”.


  • In the sed contra of Article 2, Aquinas quotes the famous Johannine Comma as an authority in favour of the tri-personality of God. Although the canonicity of this writing is disputed, it can still be considered at the very least as an ancient authority.
  • Aquinas’s reduction of the four real relations in the Godhead to the three persons may seem a bit of an ad-hoc sleight of hand to accommodate the filioque. However, one might note that the problem doesn’t simply go away if one insists that the Holy Spirit proceeds only from the Father, and even might be considered worse if this were the case. Having two real relations (paternity and spiration) associated with the Father would seem to associate two persons with the Father!
  • In the de potentia (Q.9 A.5) Aquinas writes that “The plurality of persons in God is an article of faith, and natural human reason is unable to investigate and adequately understand it.” We emphasize again that Aquinas is not trying here to derive this truth of faith from reason but is trying to show that it is at least rationally coherent.
  • The difficult notion of transcendental multiplicity is discussed at more length in Aquinas’s de potentia Q.9 A.7.

Saturday, 13 November 2010

Question 29 - The Divine Persons


Aquinas has now established that there are real relations in God and that, as a consequence of divine simplicity, these relations are substantial. He has also identified the connections between the notions of procession and relations. Having dealt with these highly abstract concepts, Aquinas now devotes Questions 29-38 to an understanding of the idea of “persons” within the Godhead, connecting this notion with those of procession and relation, and providing a detailed discussion of each person. In Questions 39-43 he will then discuss in more detail the relations between the persons of the Godhead.

Why this Question Matters.

Aquinas is now aiming at a metaphysical elucidation of the classical Christian affirmation that God is three persons (Gk. hypostases) in one substance (Gk. ousia). The next step in this process is for him to address the question of what is meant in this context by a “person”. Aquinas has available to him a number of different definitions of personhood current in medieval theology; the one he favours is that of Boethius: “The person is an individual substance of a rational nature”. One of the major strengths of this definition is that it applies not only to human persons but can also be applied, by analogy, to angels and to divine persons; it is an expansive and inclusive definition. However, Aquinas has to explain carefully what the terms of the definition mean as it is easy to misunderstand what it is driving at. Having established a metaphysical definition of “person” he then has to discuss the various Greek and Latin terms used in Trinitarian theology, as to avoid later confusion. Finally, Aquinas delves into how the notion of person applies analogically to God: from this discussion will emerge the critically important idea that the persons within the Godhead are the subsistent relations identified in the previous two questions.

The Thread of the Argument

A1: Aquinas first addresses the suitability of Boethius’ definition of person. He observes that if we consider substances in general (i.e. the genus of substance) then we quickly recognize the fact that we can identify individual substances. Individual substances have the property that they subsist in themselves: they do not require some other substance to specify their being. Contrast an individual substance like a ball with the whiteness of the ball: the ball subsists in itself, but the whiteness (which we are quite entitled to call this whiteness) depends for its being on the ball. Aquinas identifies such substances as primary substances or hypostases. Further, there is a more perfect mode of particularity to be found amongst those substances that are rational; they are in control of their actions. These rational individual substances are what we call persons.

The objections to this article mostly focus on technical issues involved with the definition. For example, if we are taking “substance” in the definition to refer to primary substance, then it would seem redundant to refer to an individual substance. Aquinas replies that the addition of the word “individual” is justified because it adds the property of “not being assumable by another”. Although this may seem odd, Aquinas is thinking of the special case of individuated human nature in Christ: from the definition of Chalcedon we know that Christ is not a human person; His personality is that of the second person of the Trinity. Similarly one might object (on Aristotelian grounds) that the definition should use “essence” instead of “nature”. Aquinas replies that the sense in which “nature” is being used here (slightly different from Aristotle’s use), which is the essence of each particular thing, is better appropriate that the more general term “essence”. The reply to the fifth objection looks forward to Aquinas’ teaching on the soul: a separated substance (such as the soul of a human after death) is an individual with a rational nature but is not a person. Aquinas replies that the soul is a part of a human person and therefore cannot be identified as being a primary substance. It may be an individual, but it is not an individual substance.

A2: Terminology has always provided an obstacle to the understanding of Trinitarian theology. Even when the Doctrine of the Trinity was approaching its definitive conciliar form there was confusion between different theological schools that were using the same words to mean subtly (and sometimes not so subtly!) different things. Therefore, it is always a good idea, before embarking on Trinitarian speculation, to have a session devoted to the defining of terms. In the objections to this article Aquinas gathers together arguments and counter-arguments to suggest that a person, an hypostatis, a subsistent and an essence are really the same things. In a twist of scholastic humour, Aquinas gathers arguments for and against this position from a single author, Boethius, who is also the author from whom he has acquired his definition of person!

In his reply, Aquinas identifies two senses of the word “substance”. In the first sense, the substance of a thing tells us what that thing is: it is a thing’s what-ness or its quiddity. In this sense, substance is the same as the Greek ousia and can be identified with essence. (As an example of this use, in the creed we affirm that the Son is consubstantial with the Father; consubstantial is translating the original Greek term homoousios).

The second sense of the word “substance” is a bit more complicated, but basically refers to an individual thing within the genus of substance. As such, it can be described in a number of different ways. It can be referred to as a suppositum, which is a logical term referring to the thing that underlies some attributes (so, for example, the ball is the suppositum that underlies the property of roundness). Secondly a substance can be called subsistent insofar as it exists as a thing-in-itself and not in another (so the ball subsists but the roundness does not, as it exists in the ball). Thirdly, a substance is a thing-with-a-nature (the ball exhibits the nature of what it is to be a ball). Fourthly, a substance is called a hypostatis or substance in that it underlies its accidents (so the ball underlies the whiteness of the ball).

All that is left to Aquinas now is to specialize these words to the genus of rational substances.

A3: The Athanasian Creed explicitly attributes personhood to the Father, Son and Holy Spirit, but one might ask whether this is a reasonable thing to do. Aquinas replies by saying that subsisting in a rational nature is the most perfect thing in the created world and by the teaching of Question 13 Article 3 it is therefore quite reasonable to attribute personhood to God. We do, of course, have to remember that such an attribution is by way of analogy and that the personhood attributed to God is attributed in a far more excellent way than it is to creatures. Aquinas’s answer to the question set in this article is quite straightforward; the bulk of the interest comes in his replies to the objections.

First of all, one might object that scripture gives us various words and formulations to describe God and that we should not go beyond these. Aquinas admits that “person” is not said of God in scripture but he claims that what personality describes is used many times of God. Moreover, if heretics are to be refuted, then new ways of expressing the ancient faith are quite appropriate. In a similar line, one might object to the very word “person” because its etymological derivation is quite inappropriate to God. But this is to fall into the etymological fallacy; because a word originates in one way this does not imply it necessarily retains such a meaning (especially when it is being used, as here, in a technical sense).

In the reply to the third objection, Aquinas adds an important qualification to what he said about hypostatis in Article 2. In the created world, a substance is called a hypostatis insofar as it underlies its accidents: but in God there are no accidents, so surely we cannot apply the notion of hypostatis to God. Aquinas replies that, when applied to God, we are not thinking of hypostasis in this way but in terms of signifying a subsistent entity. He also relates some history of the terminological arguments in the early Church: as the Greek term “hypostasis” used to be translated as the Latin “substantia” (that is, “substance” or “essence” rather than the later understanding of “subsistence”), confusion arose as the Latins thought the Greeks were attributing three essences to God.

Objection 4 collects together some terminological problems. A rational nature would seem to imply discursive cognition, which is not true of God (Question 14 Article 7); individuation would seem to imply individuation by matter, again not applicable to God; God does not have any accidents, so how can we call Him a substance? Aquinas answers the first and third of these by pointing out that rationality can be thought of in a much wider sense and that substance refers, more fundamentally, to per se existence. In answering the second objection, Aquinas introduces the important idea of individuation as incommunicability. An individual is one for whom it makes no sense to attribute its properties to something else. So, for example, it would make no sense to attribute my thoughts to some other person.

Aquinas’s answers to objections 2-4 emphasize the importance of understanding that in Trinitarian theology terms are borrowed from the metaphysics of created reality and are given subtly modified technical definitions when applied to divinity. Failure to realize this will lead to failure to understand the analogical way in which personhood is applied to God.

A4: Aquinas leaves the hardest problem until last! How are we to understand personhood when it is applied to God? How does the analogy with created personhood work? The fundamental problem lies with our use of the word “person” in everyday language: when I talk about “that person, John”, I am referring to a concrete individual, to a primary substance. When I talk about a “group of people”, I am pointing to a plurality of individuals; the concept of relation doesn’t seem to enter into view at this point. Aquinas recognizes this and recalls that some theologians (including St. Augustine) took the word “person” as signifying the essence in God. They took the relational aspects defined by conciliar decree as a sort of ad-hoc “add-on” intended to confute heretics. Aquinas is not satisfied with this explanation, arguing that it simply leaves the door wide open for further misconceptions.

Another way of looking at the use of the word “person” when applied to God is to consider that it simultaneously points to both substance and to relation. The question remains as to which is primary: does “person” signify substance primarily and relation indirectly, or does it signify relation primarily and substance indirectly? Aquinas is happy with neither of these approaches but affirms that the second is closer to the truth; still, more work needs to be done.

To do this, Aquinas notes that we have to distinguish between what we signify when we talk about a “human person” (“this flesh and these bones and this soul which are the principles that individuate a man”) and what we signify when we talk about a “divine person”. When we talk about divinity, we remember that there are no accidents in God: the divine relations subsist in exactly the same way that the divine essence subsists. Therefore Divine Paternity (relation) is God the Father (person) is divinity (essence). Therefore, “divine person” signifies a relation as subsistent. For Aquinas, when we are talking about divine personhood, relation and essence are tightly interwoven and although we might assign priority to one, we have to remember that such identification is wrapped around with provisos.

So, Aquinas notes that his solution is, in a sense, consistent with the two previous ideas about relation and essence suggested above. However, it is important to note that he has welded the two ideas of relation and essence together much more closely than the previous theological solution would have it. It is true that “person” signifies relation directly and essence indirectly but we must note that it signifies “relation” as an hypostatis when we are talking about divinity. Similarly, it is correct to say that “person” signifies essence directly and relation indirectly but we must remember the proviso that this is insofar as hypostasis and essence coincide.

Handy Concepts

  • Aquinas adopts the definition of Boethius: “The person is an individual substance of a rational nature”. It’s a good definition from his point of view as it is (i) accurate and (ii) amenable to a strategy of analogical predication.
  • Individuals are characterized by their self subsistent existence. They are also characterized by the property of incommunicability.
  • It is important to grasp the technical meaning of the terms used in Trinitarian theology and to recognize that their analogical use when applied to divinity can mislead us if we are not careful.
  • Personhood in God corresponds to subsistent relation. Later on we will see that, in a sense, we should say that God is Father not because he has brought forth a Son; rather He has brought forth a Son because He is Father.
  • In article 4 Aquinas challenges St Augustine and corrects him. It’s interesting to note the way in which he does this: he has the confidence to take on an argument of one of the greatest of the Church Fathers but he also has the humility to do this is in a very gentle way. Augustine is correct insofar as he is using the theological language available to him, but Aquinas sees the need, and has the ability, to develop what the saint has done. This is a recurring pattern in Aquinas’s work.

Tuesday, 12 October 2010

Question 28 - The Divine Relations

Why this Question Matters.

In the previous question, Aquinas identified as foundational to the explication of the Trinity the scriptural affirmation of processions within the Godhead. The fundamental points were made that these processions are immanent to the Godhead and that mistaking these immanent processions for the economic activity of the Trinity was at the root of the two important ancient heresies of Arianism and Sabellianism. Aquinas is now faced with the task of putting metaphysical flesh on the bones of this traditional interpretation of scripture. The basic tool that he has available to him is that of the category of relation. The strategy is quite straightforward: the processions within the Godhead define relations; as there are no accidents in God, these relations must be substantial rather than accidental; these relations are the persons within the Trinity. Aquinas will lay out the foundations for this strategy of persons-as-relations in this question and will complete it and elucidate the detailed consequences in the subsequent questions. All the while, he will navigate between the heresies of Arianism, Sabellianism and Tritheism.

The Thread of the Argument

A1: Aquinas is immediately faced with a fundamental problem in applying the category of relation to the processions in the Godhead. In the Categories, Aristotle identified relation as an accidental category. We know there are no accidents in God; hence such a category is inapplicable to God. This problem was well known by the time of Aquinas and had led to a realization that Aristotle’s notion of relation (set out in the Categories) had to undergo development and modification if it was to apply to the divine substance. Therefore Aquinas’s first question: “Are there any real relations in God?” is an entirely natural one to address. The objections home in on the obvious problems: there can be no accidents in God and it looks as though the relations involved here are actually “relations of reason” rather than “real relations”. The sed contra points out that if paternity and sonship are not real relations then God is not the Father or the Son in reality but only as a construct of our minds; an obvious lapse into a form of Sabellianism. In his reply, Aquinas observes that it is only in the category of relation that we find terms that express what is conceptual as opposed to real. Sometimes the relations between things are of the very nature of the things involved; sometimes, though, they are simply because of our understanding of the world. The processions in God are of the former type, because what proceeds from the Father has the same nature as the Father; this is paradigmatically a real relation.

A2: Having established that there are real relations in God, Aquinas now spells out the consequences of this by asking whether these relations are identical with His nature. One might doubt that this is so because in the normal course of events relations are something different from the substances in which they inhere. One might also point out that if God’s nature is fundamentally relational, this would seem to make His nature dependent upon something other than itself, which is clearly wrong. The sed contra points out that anything that is not the divine nature is a creature and yet, in the liturgy, we worship these relations as co-equal to God.

Aquinas briefly discusses two aspects of the accidental categories when we are talking about created things: their inhering in a subject (that is, their being is a being-in) and their specific character (or their essence). In the accidental categories other than relation, the specific character of an accident also inheres in its subject. So the accident of height inheres in a subject and is to do with the subject alone. For the accident of relation, though, things are different: the relation inheres in a subject but its specific character is associated with being directed to something outside the subject. One possible mistake to make here (which St Thomas ascribes to Gilbert de la Poirée as the reason for the latter’s condemnation by the Synod of Rheims) is to take account only the essence of a relation whilst neglecting its being-in a subject. If one does this, then a relation appears to be something that is not intrinsically associated with a subject.

Once one has realised this double aspect of the accident of relation, then the consequences of transferring this notion from creatures to the divine substance is that the being of a real relation can no longer be accidental, it has to be substantive. Therefore a real relation in God has the being of the divine essence and is therefore the same as the divine essence.

It might be objected at this point that in identifying the being of the real relations in God to be identical with His essence we have collapsed the persons of the Father, Son and Holy Spirit into one another. But we have to remember here the dual aspect of relations: they have a being-in a subject (which has here been identified with the divine essence) but they also have a specific character to do with going-out-to (or pointing-to) something (its “relational opposite”). So the being of the relations are the same, but their pointing-to their relational opposites differ. This fact is taken up explicitly in the next article.

A3: It would appear that since the relations in God are identical to His substance, then they cannot be distinct. Similarly, one might view the only real relation in God to be that of procession (or origination); any two examples of such could not be really different, but only conceptually so. Aquinas’s answer is disarmingly simple: if we attribute something to a thing then we attribute to it everything that is contained in the definition of the attribution. In the case of relation, the definition doesn’t only include the being-in of the relation but also the pointing-to of the relation. It is by the latter that the relations within God are distinct. Therefore we can quite happily affirm that when we think of the being of God, then unity follows on this being; when we think of the relations in God, distinction follows.

A4: Having established that there are real relations in God, now is the time to count them. Aquinas has already implied that there are four: those associated with Fatherhood, Sonship, Spiration and being-Spirated. The objections list a number of putative examples which would seem to suggest a multiplication of relations even as far as infinity. Equally one might object that Fatherhood and Sonship (respectively Spiration and being-Spirated) go together as a pair and should therefore only be counted once, giving us less than four.

When Aristotle discussed relations in the Metaphysics (as opposed to the Categories) he identified that relation is either founded on quantity or upon action (or being acted upon). As there are no quantities in God, the real relations in God must be founded upon action. Therefore the real relations in God are founded upon the internal processions in God (because the external relations with creatures do not define real relations in God). Therefore, from the investigations of Question 27, there can only be two opposite relations each corresponding to the two immanent processions within God. The procession of the Son from the Father gives us the relations of Paternity and Filiation; the Procession of the Holy Spirit gives us Spiration and being-Spirated). These pairs of opposed relations are genuinely distinct as each member of a pair has a different pointing-to. The examples of possible other relations presented in the objections fail, as they each boil down to a misunderstanding of God in His single act of being.

Handy Concepts

  • Following the tradition that he inherited, the fundamental metaphysical tool that Aquinas uses to build his theology of the Trinity is the notion of relation. Although the category of relation is not the most immediately given datum of revelation (that place belongs to the processions), Aquinas sees it as inevitable that any orthodox theology of the Trinity will necessarily be resolvable to one of relation.
  • The real relations in God correspond to the procession revealed in scripture.
  • In the created world, relations do not only have their being in some subject, they also have a going-out-to or pointing-to their “relational opposite”. We can distinguish between their being and their specific character. This twofold aspect of relations becomes critical for distinguishing the persons in the Trinity, when we generalize the notion of relation to the divine substance.
  • In using relations in this way, Aquinas has explained the unity of the substance (their being-in is the same) as well as the distinction of the persons (their pointing-to is different).
  • There are four real relations in God because that is what scripture reveals to us.
  • The connection between the real relations in God and the person of the Father, Son and Holy Spirit will be made in the next question.


  • It was well known by the time of Aquinas that Aristotle’s conception of relation as set out in the Categories needed to be developed in order to deal with the divine substance. (Indeed, Aristotle himself carried on developing the theory in the Metaphysics.) It is reasonable to ask whether the theory of relation was adequate by the time Aquinas applied it in his Trinitarian theology. Some would argue that his conception of relation was inadequate; others would say that it’s been downhill all the way since his time.

Saturday, 9 October 2010

Question 27 - The Procession of the Divine Persons


It used to be standard practice to divide the summa into a number of “theological treatises” and on that account, we are now moving from the “Treatise on the One God” to the “Treatise on the Blessed Trinity”. It’s now less fashionable to make such a hard and fast division, and more in keeping with the times to emphasise the unity in the work as a whole and the intimate connections between the different parts. There’s truth in both approaches: to cut the summa up into pieces risks losing the unity that is undoubtedly there; but equally we must note that the character of the work changes at certain key points, which Aquinas himself often signposts. At this point in the summa, Aquinas tells us that we are now to turn from considering the oneness of the divine essence to those things that pertain to the Trinity of persons in God.

It is important to note that, although this is not a hard division, we are moving from the realm of “natural theology” (where metaphysics can conclusively demonstrate facts about the existence and being of God) to the realm of “revealed theology” where facts about God are discerned by reason applied to the data of revelation. Aquinas firmly believed, in opposition to a number of prominent theologians of his time, that the truths of the Trinity cannot be demonstrated by means of metaphysics; they are purely truth of revelations. This does not mean that he believes that metaphysics has no role to play; on the contrary, the role of metaphysics is to show that arguments against the truths of faith are not proofs. Metaphysics can be used to show that the truths of the faith can be explained in a rationally coherent way consistent with other scientific (in the widest sense of the word) truths.

One consequence of this is that there may be many ways of approaching and expressing the truths of the Trinity; unfortunately not every way of approaching the Trinity, however attractive it may be, is rationally consistent in this way with the truths of faith and of reason. Aquinas will spend much of his time in this part of the summa showing how it is possible to misunderstand the data of revelation and how this has led people into error throughout the ages.

Aquinas’s presentation of the doctrine of the Trinity does not arise out of thin air. He is indebted to the Fathers of the Church who came before him and especially to St Augustine (in the West), the Cappadocian Fathers (in the East) and the some of the documents of the early ecumenical councils. However, it is also true to say that Aquinas produces a creative synthesis out of the tradition that is handed on to him that goes deeper and further than that tradition.

Why this Question Matters.

One of the most fundamental questions in the consideration of the Trinity is: where to start? What are we to make of the data of revelation; what in it is most foundational for Trinitarian theology? The Christian doctrine of the Trinity is revealed in scripture but, as is well known, it took some centuries before the Church was able to elaborate and define what it meant by the claim that God is one substance in three persons, by an extended reflection on the meaning of scripture. St. Thomas starts his teaching on the Trinity by identifying that the most fundamental notion that scripture gives us is that of an “immanent procession” in the Godhead. We are quite used to the creedal claim that the Holy Spirit “proceeds from the Father and the Son”; what Aquinas notes is the scriptural teaching that, in sense, both the Son and the Holy Spirit “proceed” from the Father and that the “procession” of the Holy Spirit has a double meaning (which he will elaborate in later questions). In this question, Aquinas starts his meditation on the Trinity by elaborating the notion of “procession” and by introducing two ancient and fundamental heresies (Arianism and Sabellianism) that demonstrate how misunderstanding the idea of procession can lead to theological shipwreck.

The Thread of the Argument

A1: Following his standard practice, Aquinas first of all asks whether it makes any sense to talk about “processions” in God. The idea of this question, of course, is to understand the correct meaning of the word in this context and to point out how it can be misunderstood. In everyday life, “procession” usually means something like “a going out from”. The objections build on this observation to claim that such a notion of procession is incompatible with the divine essence. There is no motion in God, so there cannot be a “going out”; if something “goes out”, it is different from what it goes out from, but there is no diversity in God; if God goes out from God, it would seem that the first “God” referred to cannot be a first principle. The sed contra observes that scripture tells us about this “going out” from God; what then does it mean?

In his answer, Aquinas introduces a distinction between what we now call the “immanent” and the “economic” processions in the Trinity. To do this, he introduces us to the Arian heresy, which took the Son to be first among the Father’s creatures and the Sabellian heresy which took the Father, Son and Holy Spirit to be different modes of existence of the one God. He does this because he identifies the root of their mistakes to lie in their identification of procession purely with “economic procession”. This latter refers to the going out of the Son and the Holy Spirit into the created world from the Father. Aquinas claims that what the Arians and the Sabellians missed was the fact that this economic procession is founded in an “immanent procession", a procession that goes on within the Godhead itself. To help us visualize this idea, he gives us the analogy of the intellect understanding something; such an understanding, in a sense, both goes out from the intellect but also stays within the intellect itself. The intellect may present such understanding to the will so that (economic) action may follow upon this immanent understanding. Later on, Aquinas is going to push this analogy further; here he hints at by introducing the phrase “the word in the heart” to describe such a process of understanding. That Aquinas intends the reader to make the connection with the opening of St John’s Gospel should be clear.

The answers to the objections should be clear; the objections make the same mistake of identifying the economic processions of this world with the immanent processions within the Godhead. However, the reply to the third objection hints at a future theme. We’ve already seen that creation goes forth from God’s creative knowledge; itself a kind of procession. It is no coincidence that Aquinas will consider creation immediately after his teaching on the Trinity, as he sees the creation as an act of the whole Trinity.

A2: Having established the fundamental nature of procession within the Godhead, Aquinas immediately turns to the tasks of specializing this notion to the cases of the Son and of the Holy Spirit and of relating procession to the other words that scripture and tradition use to describe the relations between the persons of the Trinity. In this article, he looks at the description of the Son as “begotten of the Father before all worlds” (as the Nicene Creed puts it); the notion of “begetting” or “generation”. Applying the notion of “generation” to the Son might appear troublesome: we use the word “generation” to refer to the coming to be (and decay) of material things, this would clearly not work as far as the Son is concerned. Similarly, if Aquinas is going to push his analogy of procession with the conception of an idea (or word) in the mind of God, then how does he explain that we simply don’t apply the word “generation” to this mental process? Finally, if something is generated from another thing, it receives its existence from the latter. But if the Son is fully God, then He must be self sufficient existence and not receive His being from another.

Aquinas points out that “generation” can be used with a very wide meaning corresponding to a general notion of coming into existence and going out of existence but that it can also be used to refer to a process whereby something living comes into existence with the same nature as that that generated it. It is this latter use that carries over by analogy to the case of the Son being “generated” by the Father.

Replying to the objections, Aquinas points out that the first objection is founded upon the wider meaning of the word “generation”. The second objection is trickier. When we form an idea in our minds, that idea does not have the same nature as our minds, so in this sense the analogy fails. However, God’s act of understanding is His very being; hence the Son that is generated in this sense does have the same nature as the Father. Finally, and trickiest of all, one has to accept that the analogical use of the word “generation” has its limits. When we are talking about the generation of the Son, we have to understand that whilst He is generated by the Father, He doesn’t receive existence into some subject but rather He receives His existence as from some principle. The concern here is to avoid any notion of “subordination” in the Trinity (that the Son and the Holy Spirit are in any sense inferior to the Father) whilst recognizing that there are relations of order in the Trinity (so that the Father can be said to be the principle of both the Son and the Holy Spirit).

A3: Aquinas has connected the fundamental notion of procession with the generation of the Son and now he turns to the procession of the Holy Spirit. There are objections to the idea of more than one procession in the Godhead: if two, then why not three and four and so on? There is only one nature of the Godhead to be communicated, so how can there be more than one procession communicating that nature? The third objection is an excellent example of Aquinas anticipating an objection to the solution that he is going to propose: the procession of the Son corresponds to the going forth of a word in the intellect of God; the only other similar possibility would seem to be that the procession of the Holy Spirit corresponds in some way to the will of God. But in God, the Will and the intellect are the same thing, therefore there cannot be two processions.

Aquinas does indeed turn to the will of God as the solution to this question. In our minds, the intellect proposes something to the will as a good and the will is drawn by its nature to this good: there is a coming forth of love, immanent to the will, towards that good. By analogy, the immanent procession of the Holy Spirit corresponds to the procession of love towards the word in the intellect of God. The first objection is met as there is naturally within the Godhead, this structure of intellect and will, and no more. However, Aquinas will devote Article 5 of this question to a further consideration of this issue. The second objection is met by observing that what is true in the created word is not necessarily true of God. In God, any procession would be a means of communicating the divine nature.

The third objection goes to the heart of the difficulty of the doctrine of the Trinity; it challenges any notion of there being “structure” within God, as everything in God is in some sense “convertible”. Aquinas, of course, spent a lot of time showing that we can talk about things like intellect and will in God and that these notions, though imperfect, have some correspondence with reality. So here he is not going to give up so easily! Nothing can be loved by will unless it is conceived in mind so these processions, although they are related in being the same substance, are distinct as processions.

A4: Having established that it is fitting that the procession of the Son be called generation, Aquinas now has to face the awkward consequence of his argument that one might also call the procession of the Holy Spirit generation as well. This would be rather embarrassing, as Christian tradition (here Aquinas quotes the Athanasian Creed) holds that generation is unique to the Son. To answer this, Aquinas points out that intellect and will differ from one another in the following way. The intellect understands something when there is a likeness of the thing in the intellect for it to ponder. The will wills something not because the something is present in likeness but because it tends towards that thing. Therefore the procession that corresponds to the intellect carries within itself the very notion of likeness and thus corresponds naturally to the notion of generation (whence like comes from like). The procession corresponding to the will, on the other hand, carries with it the notion of tending-towards. We don’t have a particular name for this procession immediately to hand, but scripture indicates that we can liken this to the breathing of a spirit and so we can call it “spiration”.

A5: Returning to the first objection to Article 3 above, Aquinas now shows why there are only two processions in the Trinity. Given the way that Aquinas has explained the notion of procession, he seems open to the objection that over and above intellect and will we might attach a procession to God’s power or to His goodness. Similarly, we observe that created minds have many more than one single idea and therefore surely God must have many ideas, each of which would correspond to a procession. To meet these objections Aquinas returns to emphasize the fact that we are considering immanent processions in this question. We will see later that many things do proceed from the Godhead externally but as for immanent processions, he observes that in spiritual beings (and therefore by analogy in divine beings) there are only two actions that remain within the agent, those of intellect and will. Consequently there can only be two immanent processions that correspond exactly to these.

Handy Concepts

  • The fundamental data of revelation concerning the Trinity lies in the notion of immanent procession within the Godhead. Although our experience in the world is of the action of the economic Trinity, we do not have to work backwards from this (as we did when we inferred God’s existence from his action in the world) to the immanent Trinity as the latter is revealed directly in scripture.
  • Two of the “great” early Christian heresies were rooted in a misidentification of the economic Trinity with the immanent Trinity. Plus ça change, plus c'est la même chose.
  • The procession of the Son corresponds to the idea of a word in the intellect; the procession of the Holy Spirit corresponds to the loving movement of the will towards that word.
  • The procession of the Son can fittingly be called “generation”.
  • In the case of the Holy Spirit, the word “procession” is overloaded. The word is used in common with the procession of the Son but is also used as a particular name for the procession of the Holy Spirit (which can also be called “spiration”).


  • The idea that we can use the methods of metaphysics in order to discern truths contained purely in revelation (as opposed to natural theology) may seem troubling, if not repugnant. Aquinas was well aware of this objection and gives an extended apology for his approach in the opening two questions of his commentary Boethius’s “On the Trinity”.

Thursday, 7 October 2010


One of the important metaphysical concepts that Aquinas makes use of is that of a “relation”. He uses the concept in Ia q.13 in talking about how we are related to God and how God is related to us. When he comes to consider the Trinity, the notion of a relation becomes central. Aquinas will develop an exposition of the Trinity that maintains metaphysical coherence between the idea of God as “one” and God as “three” by identifying the “hypostases” (or “persons”) within God as “subsisting relations”.

This article is intended to give a brief overview of how medieval philosophers thought about relations as an aid to understanding how Aquinas uses the notion.

There is a superb article on “Medieval Theories of Relations”, by Jeffrey Brower, over at the online “Stanford Encyclopedia of Philosophy”.

In many ways, this article simply condenses and simplifies what is said there, so if the reader finds what is written here intriguing, puzzling or simply infuriating, relief may be had by going on to read Brower’s article.

We’re thoroughly used to using the notion of a relation in everyday language. For example:

  • “James is taller than Richard.”
  • “This potato is heavier than that tomato.”
  • “Hannah is my daughter.”

These examples seem quite benign, but when one starts to consider the metaphysics underlying such expressions of relation one is rapidly exposed to some surprising difficulties. For example, it would seem quite reasonable to think that “James is taller than Richard” expresses an objectively real fact about the world rather than simply being a consequence of how our minds organize their thoughts about the world. This being so, it would seem that a relation has to be some sort of real thing in the world as opposed to something that only exists in the mind. Where then does this relation exist? What is it? Does it have form and matter?

Medieval philosophers started their thinking about relations from Aristotle’s treatment in the Categories (which we mentioned in our Introduction to Metaphysics). In this work, Aristotle divided what we can express about things into two classes: substance and accident. Aristotle characterises substance as that which cannot be predicated of anything or said to be in anything – “primary substances”; or as that which can be predicated of something but cannot be said to be in anything – “secondary substances”. On the other hand, accidents are predicated of things in the sense of being (or inhering) in things. There is a primary division between being in a subject (accident) versus not being in a subject (substance).

So, for example, when we say that “that cat is white”, we are predicating something (whiteness) of some thing (“that cat”). The whiteness inheres in the cat as an accident, whereas the phrase “that cat” points to that particular cat rather than being predicated of it, and certainly does not inhere in the cat. So in our sentence, “that cat” points to a primary substance and “white” is an accident inhering in that particular cat. Similarly, in the sentence “that animal is a cat”, “that animal” points to a primary substance and “cat” is a secondary substance, a universal.

In the Categories, Aristotle went on to divide up the class of accidents into nine subclasses. One of these subclasses is what we are considering here, the notion of “relation”. Aristotle’s original Greek described “relation” as “pros ti” (“towards something”) and this description gives us an important clue about the metaphysical opportunities and problems associated with relation. The other eight accidental categories are all naturally associated with a thing-in-itself: we can happily say that “the ball is big” (the category of quantity) or “the ball is in the sandpit” (the category of place) but when we come to talk about relations involving the ball, we need something else there as well: the thing that enters into the relation with the ball: “the ball is bigger than the ant”.

When we think of our original examples, a sentence like “James is taller than Richard” seems to involve a number of aspects. First of all, each of the participants in the sentence has a particular height; the relation between the heights of James and Richard is said to be founded in the heights of each individual. Next, there is a comparison between the heights that dictates whether the relation holds or not. Finally there are the questions of where this relation exists as an accident and the sense in which we can say that the existence of this relation is real.

In the Categories, Aristotle held that a relation is not a separate thing to which the participants in the relation are jointly attached but is really explained by the foundational accidents involved. This idea bears a sort of similarity to Aristotle’s approach to universals; universals are instantiated in their exemplars, there is no Platonic third realm of universals where they have a totally separate existence. However, for Aristotle, relations (as universals) are still real entities with their own existence.

In the Middle Ages, although philosophers followed Aristotle in teaching that relations are real entities explained by foundational accidents, there was a dispute between those that held that relations amounted to no more that these foundational accidents (“reductive realism”) and those who held that although relations were founded on these foundational accidents, relations were sui generis accidents (“non-reductive realism”). These latter (including Aquinas) held that we should distinguish between such a thing as the accident of height and the accident of pointing-towards other heights founded upon the accident of height.

There’s a major distinction to be made between some modern approaches to relations, where they are considered to be things that hold between two or more things and the Aristotelian (and medieval) approach in which they inhere in one thing pointing towards another.

Medieval philosophers were also willing to recognize a distinction between propositions and situations that define real relations (so called “relations according to being” or “relationes secundum esse”) and propositions and situations that simply express relative terms (“relations according to speech” or “relationes secundum dici”). In other words, a distinction was made between what serves to relate things and what simply stands in some relation. For example, if we were to come across a decapitated body with its head by its side, we might say “this is a head” and “this is a body”. “Body” and “head” would appear to be relative terms related to each other, but do “this is a head” and “this is a body” express real relations? The problem is that if so this would appear to identify substances with relations, but according to Aristotle relations are accidents. The solution is to recognize that these relative statements are describing parts of substances and not relations. If we were to go on and say “this is the head of that body” we would now be expressing a relation between two substances whose accidental situation indicates that they originally came from one substance. Aquinas refers to this distinction in Ia q.13 a.7 ad1.

Let’s consider another problem: think about the relation of “equality”. “James is the same thing as James” seems to express an obvious fact about reality. If this relation is a real thing, which we’ll call “R1”, then we can immediately observe that “R1 is the same thing as R1”. This is itself a real relation which we’ll call “R2”. We can then apply this reasoning to R2 to get R3, and so on. We soon see that our simple notion of the relation of equality implies an infinite sequence of “real things” associated with one apparently simple relational statement! This would seem the sort of hopeless mess that would have William of Ockham rubbing his hands in glee. The way out of this conundrum is to observe that when we say “James is the same thing as James”, we’re not really saying anything about James. We could quite happily substitute the word “James” with any “x” that named a substance and we’d still have a true statement. Statements like this do not express real relations (“relationes reales”) but what the medieval philosophers called “relations of reason” (“relationes rationes”). In this example, we notionally posit a relation founded on the unity of the substance concerned.

There are also problems in other directions and Aristotle seems to have identified some of these problems in his Metaphysics, suggesting that he himself knew that the treatment in the Categories would not ultimately be sufficient for all circumstances. Much of the medieval debate about relations amounts to a debate about how to relate the theory of relations given in the Categories with that advanced in the Metaphysics and then how to square this resolution with the data of revelation about God.

As we saw, our original examples given above seem to be based on accidents in both the objects appearing in the relations concerned. “James is taller than Richard” depends upon a fact about James’ height and a fact about Richard’s height and a comparison between the two. However, this need not be the case.

  • “Richard is thinking about Fiona.”

This sentence seems to express a relation between Fiona and Richard that only depends upon some fact about Richard (that he is currently thinking about Fiona). There would seem to be nothing about Fiona that is involved in this relation. (If one argues that “Fiona is known by Richard” is the underlying fact about Fiona that grounds this relation, one should consider that this is just another way of saying “Richard knows Fiona”).

  • “I have arrived at a position to the right of the column”.

Similarly, this sentence provides another example where it is a fact about me that founds the relation rather than any fact about the column. In both of these examples there is a profound asymmetry. Medieval philosophers dealt with these examples by using the idea of a “relation of reason” that we saw above. They considered that even if there were no case for considering one side of the relation being real (or extra-mental) we should consider it as if it were so, projecting the mental relation onto the subject concerned. In examples such as these, there is both a real relation and a relation of reason involved. Philosophers such as Aquinas were quite happy to consider that certain relations did not introduce something in extra-mental reality. The discussion in Ia q.13 a.7 gives a clear example of Aquinas exercising these concepts of real relation and relation of reason simultaneously.

  • “I am thinking about those two chairs.”

This sentence would seem to set up a relation between two chairs (as well as a relation between me and the two chairs). But surely this relation expresses no facts inherent in the chairs themselves. Here we have an example where the relations involved are purely those of reason.

Finally, we come to the examples that motivated much discussion in the middle ages about the nature of relation and about whether the notion of relation put forward by Aristotle was adequate when dealing with the metaphysics of theism.

  • “God the Son is the son of God the Father.”
  • “The Holy Spirit proceeds from the Father and the Son.”

We already know from Aquinas that when we talk about God, we often talk analogically. Does this apply here, when we talk about relations involving God? Or are these statements literally true, and if so, how are we to understand them?

If we take the statement “Jesus is the Son of God” as being true, then it appears to set up a relation between God the Father and the God the Son. If we were to consider this relation to be purely one of reason, then we would fall into the heresy of Sabellianism (the idea that the distinction between the persons of the Trinity is purely notional). If we were to suggest that the relation is real in the Son and a relation of reason in the Father, then we would be falling into the error of Arianism (that the Son of God is a creature) because the reality of the relation in the Son would correspond to an accident in the Son which would imply that the Son was a creature. If the relation were real in both God the Father and in God the Son then we would seem to have set up accidents in both of them, contrary to the doctrine of divine simplicity.

Aquinas’s solution is simple and bold: when we consider relations concerning the divine persons, those relations can correspond to substances rather than accidents. Aquinas will spend much of Questions 27-43 of the first part of the summa developing the idea that the persons of the Blessed Trinity are subsisting relations within the Godhead.