A famous medieval debate concerned the possibility of either, on the one hand, proving that the created universe must have existed forever or, on the other hand, whether it could not have existed forever. The relationship of this argument to the creation account given in the book of Genesis is manifest: if the eternity of the universe is provable, then the Genesis account has to be interpreted very broadly indeed. Aquinas held to the position that neither the eternity nor the non-eternity of the universe could be proved and that the non-eternal creation of the universe is therefore purely an article of faith. In this question, Aquinas lays out his reasoning on both these questions and discusses the relation between creation and time.
The Thread of the Argument
A1: Ten supporting objections are given to the thesis that the universe must have existed from eternity. Rather than go through these each in turn, it suffices to point out that many of them are based on the same difficulties that Aquinas had to answer in Ia.q45 when dealing with the very notion of creation ex nihilo. In particular, our observation of the created universe suggests that any change or being has to be preceded by a previous change or being. Similarly, if we make the mistake of seeing creation purely in terms of being a change, then it has to be considered a change in some subject which would have to appear to pre-exist the act of creation.
Aquinas argues that the existence of the world is a consequence of God’s will and that, as argued in Ia.q19.a3, there is no metaphysical necessity constraining God from holding the created universe in being for whatever type and length of duration He wills. Having set forth his position Aquinas, showing due deference to the reputation of Aristotle, argues that the latter’s arguments on this subject were not attempts at a proof of the eternity of the universe but were demonstrations that earlier accounts of the coming to be of the universe were faulty.
The fourth and the eighth objections demonstrate a lack of appreciation for the utterly radical nature of creation ex nihilo; Aquinas takes the opportunity to amplify just how radical this idea of creation is. The fourth objection suggest that before the universe exists there would have to be a vacuum in the place where the universe comes to be (and it was widely believed that a vacuum was impossible); the eighth suggests that if God existed before the universe was created then time must have existed before the universe existed in order for there to be a “before” and an “after”. Aquinas replies that a vacuum is not nothing (something modern physics would applaud!) but rather a space capable of holding a body; not even this exists before creation. Likewise, time did not exist before the creation of the universe; when we speak of God being in eternity, we are claiming much more than that God exists in a temporal forever.
A2: Conversely to the arguments of article 1, the idea that the universe could have existed forever would seem to be troubling. If we think of the universe as co-eternal with God then it’s hard to think of it being created, even if its being depended entirely upon Him; if there never was a time when the universe didn’t exist then we can’t say that it came to be, which is surely what we mean by creation. Likewise, if the universe has always existed, then time would have had to traverse an actual infinity to arrive at now. Aquinas answers these objections by pointing out that “ex nihilo” refers to “out of nothing” rather than “after nothing” and that it is hard to make any sense of the idea of a traversal with an undetermined point in the infinite past.
Aquinas’s major argument is similar to that given in answer to article 1: the existence or otherwise of the universe is entirely dependent on God’s will, but we cannot know the content of God’s will by natural arguments but only by revelation. He also offers a supporting argument from the eternal existence of universals; their eternal existence demonstrates that we cannot show that concrete particulars have not always existed.
The reply to the seventh objection gives us a succinct summary of Aquinas’s teaching on the difference between per se and per accidens series of causes that we discussion in the Introduction to Metaphysics and which Aquinas uses in the proof of the existence of God in q2.a3.
A3: In modern physics, time is considered to be part of the space-time continuum that comes to be in the big bang. This immediately poses awkward questions that bear a surprising similarity to some of the questions that Aquinas has addressed above. In particular, it is hard to get the mind around the idea that time is created in the creation of the universe, and harder still to start thinking about what might have happened “before” the big bang. So, now looking at this from a philosophical and theological point of view, does it make sense to say that the creation of the universe occurs at the beginning of time if time itself is created along with the rest of creation?
Aquinas answers that this phraseology is to be interpreted in accord with the standard interpretation of scripture. This states that four things were created “in the beginning”: the highest heaven; corporeal matter; time; and angelic nature. The difficulties that we may have with this concept are all related back to how we understand the idea of creation ex nihilo.
- There can be no metaphysical proof that the created universe has existed forever.
- There can be no metaphysical proof that the created universe has not existed forever.
- Creation is an act of God’s will and therefore our knowledge of the eternity or non-eternity of creation comes from what has been revealed to us of God’s will.
- Aquinas produced the short document De Aeternitate Mundi during the medieval controversies about the eternity of the universe.
- Aquinas’s argument against the possibility of proving the finite duration of the Universe using an argument based on the eternal existence of universals seems to be rather weak, or at least missing a few steps of explanation.