Thursday, 31 December 2009

Question 4 - God's Perfection

Why this Question Matters.

Matthew 5:48 tells us to “Be perfect, as your heavenly Father is perfect”. This is always something of a puzzle for those that hear this teaching, as we are so aware of our imperfections before God. Later on in the summa, Aquinas is going to enquire into what it means for us to be perfect and into how the life of grace forms us in such perfection. But first of all, he is going to ask about what perfection is in general and in particular what it means when we ascribe perfection to God. Aquinas will conclude that the notion is to do with how God is the first efficient cause of every created thing; since effects resemble their causes, it is natural at this point for him to also inquire into it means for a creature to resemble God.

In the preamble to this question Aquinas notes that there is a relationship between the idea of perfection and the idea of the good. As he is going to discuss the latter in the next question, it makes sense to see these two questions as a doublet.

The Thread of the Argument

A1: If we look at the etymology of the word “perfect” we see that it carries meanings like “thoroughly made” or “completed”. Since God is not in any sense made, then surely we should not apply the idea of perfection to God. Similarly, if we consider God to be the origin of all things and we observe that origins tend to be less perfect than the completed beings to which they are directed (an acorn being less perfect than an oak tree, for example), then it is hard to attribute perfection to God.

Aquinas answers by making a distinction between meanings of the word “origin”. One should observe that God is the origin of a thing in the sense that He is the first efficient cause of that thing, sitting as the foundation of the chain of causes bringing it from potentiality to actuality. This is in contrast to the notion of origin, exemplified by the acorn, which refers to something material which is in potentiality to become the actuality of the completed thing.

Everything created is a composition of actuality and potentiality and God is the first efficient cause of the movement of such beings from potentiality to actuality. Since the first efficient cause of everything has to be the most actual thing possible, it is reasonable to identify this thing as the most perfect of all things. Indeed, we can go on to extend this notion of perfection by analogy from God to creatures by saying that something is perfect when it has achieved actuality in all that makes it what it is.

Returning to address the objections, we must admit that in ordinary use the word “perfect” does refer to things that are made. But if we are to have a vocabulary that refers to God, we must be able to extend ordinary meanings into the sphere of the transcendental. Indeed, we might even consider that the notions and meanings we apply to created things themselves are better derived from analogies that we make between God and created things. Likewise, if we think about material origins, like the acorn as the origin of an oak tree, we have to remember that the acorn has an origin too! Anything that is in potentiality must have derived its being from something in actuality, and only something actual can actualize something that exists in potentiality. God lies behind all this as the first efficient cause.

A2: God is not only perfect, but His perfection contains the perfections of everything else. Aquinas argues for this point of view by observing that since God is the first efficient cause of created things, and since causes contain their effects, therefore God must contain the perfections of all created things in the highest manner possible.

We saw in Ia.q3.a3 that effects resemble their causes in that something of the nature of a cause must be expressed in the effect that the cause has. If we think about efficient causes, then we can say more: the perfection found in an effect must derive from the cause. After all, it is the efficient cause that moves the thing from potentiality to actuality and is therefore the source of the perfection of the thing. What is more, we can identify this happening both when the efficient cause is the same sort of thing as the effect (i.e. when the cause generates the effect formally) and when they differ (i.e. when the cause generates the effect eminently).

Aquinas goes on to offer a second argument in favour of this position by observing that God is a self-subsistent being, containing the full perfection of existence. Since the movement of potentiality to actuality involves the coming to be of that actuality, created things are perfect inasmuch as they exist in some way. God, being the efficient cause of that being, must contain that being most perfectly within Himself.

A3: There is a profound distance between God and His creatures, but it is reasonable for us to ask how a creature might be considered to resemble God. After all, we are the effects of God’s causality and effects resemble causes. We also have the backing of scripture (Genesis 1:26 & 1 John 3:2) that tells us that we are like Him in some way.

Aquinas answers by observing that similarity is founded in some sort of sharing of form. Therefore to answer the question of the similarity of creatures to God, we must first look into the different ways in which forms may be shared. Then we may identify if any of these ways of sharing form can be applied to the case of creatures sharing form with God. Aquinas rejects a couple of cases of sharing a form, (for which he gives examples of things being identically white and not-identically white), before he settles on the answer that he considers adequate for this question. When two things share a genus or, even more closely, share a species, there will be a closeness of resemblance between them that corresponds to this sharing of genus or species. For the case of God, outside of any genus, the similarity has to be far more remote. What God and creatures do share is being. Now, God is being by His very essence and creatures participate in being in receiving their being from Him. It is in this way that creatures can be considered to resemble God, by participation in the being that He is by essence.

The third objection argued that there can be no resemblance between God and creatures on the grounds that resemblance is founded upon similarity of form and there can be no similarity of form between creatures and that whose essence is to exist. In answering this objection, Aquinas makes the fundamental point that, once we have identified what it means for a creature to resemble God, we have to recognize that there is a profound asymmetry in the resemblance between God and creatures. Creatures can be considered to resemble God, but God cannot be said to resemble creatures.

Handy Concepts

  • God is the most perfect being in the sense of being the first efficient cause of the being of all things and therefore the most actual of all things. Perfection in creatures may be thought of as actualized potentiality; similarly, it may be thought of as fullness of their being.
  • God, because He is the first efficient cause of all created things, contains all the perfections of all these things within Himself.
  • As effects resemble causes, so God’s creatures resemble Him. But this is a remote resemblance founded on the fact that creatures participate in the being of God. There is a profound asymmetry in the resemblance: creatures resemble God in this way, but God does not resemble creatures.


  • At this stage, Aquinas’ notion of our similarity to God may seem not to do justice to the scriptural account. However, Aquinas will develop this account over the next few questions, so it is important to not leap to conclusions quite yet. Questions Ia.q12 and Ia.q13 will be very important in this regard.
  • In this question we get strong hints of Aquinas’s doctrine of the Analogy of Being. Creatures receive their being from God and participate in that being, but as the being of the creature is not identical with being, this being is analogical to God’s being. For more details on the analogy of being, please refer to the bibliography. For a modern, short, but quite sophisticated treatment of the subject, take a look at Steven Long’s book Analogia Entis.

Revised 18/03/2101


  1. very hard concept to understand, i have to keep reading over and over and over again. thanks for making it a bit clearer though

  2. Steve & I had a little discussion about this question and the next:

    1a.4.1 I thought St Thomas said that there was no composition of genus and difference in God (1a.3.5). Yet here he says ’However, God is posited not as the first material principle, but as the first principle in the genus of efficient causes; and the first efficient principle has to be absolutely perfect.' It looks as though God is back to being part of a genus. What's going on?

    I think that this is one of those awkward issues of translation. The latin reads: “eus autem ponitur primum principium, non materiale, sed in genere causae efficientis, et hoc oportet esse perfectissimum.” The issue here is what Aquinas means by “in genere”. This is one of those cases where Aquinas has used a very general (if you’ll forgive the pun) latin word (“genus, generis”) and Freddoso has chosen to translate it as “genus”. I’m not so sure that this is a wise choice among the wide range of possibilities! The old Dominican translation reads “Now God is the first principle, not material but in the order of efficient cause”. Davies and Leftow translate “But we take God to be the first source insofar as he is an efficient cause, not insofar as he is something material”. The point that Aquinas is making here is that we need to shift our thinking away from the “order of material things” to “the order of efficient causes” when thinking about God; he’s not using “in genere” to stick God into a genus but rather to talk about how God is first cause.