This post examines Richard C. Potter's solution to the problem of reconciling creatio ex nihilo with ex nihilo nihil fit in his valuable article, "How To Create a Physical Universe Ex Nihilo," Faith and Philosophy, vol. 3, no. 1, (January 1986), pp. 16-26. (Potter appears to have dropped out of sight, philosophically speaking, so if anyone knows what became of him, please let me know. The Philosopher's Index shows only three articles by him, the last of which appeared in 1986.)
I. THE PROBLEM
We first need to get clear about the problem. On classical conceptions, God creates ex nihilo, out of nothing. He is not a Platonic demiurge who operates upon some preexistent stuff: he creates without it being the case that there is something out of which he creates. Nor does God create out of himself, a notion that presumbaly would give aid and comfort to pantheism. God creates out of nothing. Given that God creates out of nothing, how is this consistent with the apparent truth that something cannot come from nothing? The latter, the principle of ex nihilo nihil fit, seems to be an intuitively self-evident metaphysically necessary truth. Let us assume that it is. As metaphysically necessary, it is not a truth over which God has any control. Its truth-value is not within the purview of the divine will. Our problem is to understand, if possible, how it can be true both that God creates out of nothing, and that out of nothing nothing comes. Potter offers an ingenious solution.
Ex nihilo nihil fit is interpreted by Potter in terms of the following Principle of Creation by Compounding:
PCC. For any object O and time t, if O comes into being at t, then there exist some objects out of which O is composed and those objects existed prior to t.
Potter sees the problem as one of reconciling (PCC) with the following principle:
ENP. God created contingent objects in such a way that there was a time t1 at which contingent objects came into being, although there was no time prior to t1.
On the face of it, (PCC) and (ENP) are logically inconsistent.
II. POTTER'S SOLUTION
Potter attempts to evade the inconsistency by distinguishing between two senses of 'a time' as it figures in (ENP). The phrase can be taken to refer to an instant, or to a finite interval. (ENP) thus splits into two principles:
ENP1. God created contingent objects in such a way that there was an instant t1 at which contingent objects came into being, although there was no instant prior to t1.
ENP2. God created contingent objects in such a way that there was a finite interval t1 during which contingent objects came into being, although there was no interval prior to t1 and no instant during t1 at which contingent objects failed to exist.
It is clear that (PCC) and (ENP1) are inconsistent. But (PCC) and (ENP2) are not inconsistent. To appreciate this, one must realize that an interval of time need not have a first instant. It may be that the first interval of time was 'open in the earlier direction,' or as Potter puts it, "open-ended at its beginning." If we take the concept of an instant as undefined, we may define an interval of time to be a set S containing at least two instants such that (i) every member of S is an instant; (ii) between any two members of S there is a third member that comes before one member and after the other; and (iii) any instant that comes before one member of S and after another member of S is a member of S.
Clause (ii) of this definition insures that an interval is an infinite set of instants: if between any two there is a third, then between any two there are infinitely many. The members of S are densely ordered in that they are packed together like the rational numbers. Given that an interval so defined is open in the earlier direction, it follows that for any member of the interval, there is some other member of the interval that comes before it. It follows that there can be a first interval of time, an interval that precedes every other interval, without there being a first instant of time. To say that interval S wholly precedes interval T is to say that every member of S comes before every member of T. The reason there can be a first interval without a first instant is because the interval is open in the earlier direction.
Now if there was a first interval of time, a first year some fifteen billion years ago let us say, but no first instant of time, then God can create the physical universe without violating (PCC). For at any instant during the first interval, there will already exist contingent beings that God can operate upon in order to create further contingent beings. Thus God creates out of nothing in the following sense: God creates contingent beings in such a way that there was a time (an interval of time) that was not preceded by any interval of time. And this creation out of nothing is logically consistent with ex nihilo nihil fit because there is no instant of time within the first interval at which contingent beings did not exist.
III. A QUESTION ABOUT POTTER'S SOLUTION
Potter's solution is ingenious, but the very move he makes may perhaps be used against him by the atheist. For what could prevent the atheist from arguing that the physical universe causes itself to exist? For if the first interval of time contains no first instant, then the atheist can maintain that what exists at each instant is caused to exist by what exists at earlier instants. If so, there is no instant at which there exists something that requires something external to the physical universe as its cause. Thus to Potter's claim that God at every instant has contingent beings available upon which to operate, the atheist can respond: "But if that is the case, then why posit God as cause of the universe's beginning to exist?"
The atheist's point is that the existence of a temporally finite universe can be explained internally or immanently by construing the temporally first interval as open in the earlier direction such that every state of the universe is caused by earlier states. If every state has a physical cause, then there is no need to invoke God. Ex nihilo nihil fit is an intuitively obvious principle that threatens both the theist and the atheist.
It is a problem for the atheist since, if the universe began to exist, it could not have come out of nothing, and so appears to require a cause of its existence. It is a problem for the theist, since if the universe began to exist, it presumably did not come out of God, but was created by God as distinct from God. Not coming out of God, it came out of nothing -- but how is that possible?
Potter's solution removes the sting of ex nihilo nihil fit for the theist, but unfortunately gives aid and comfort to the atheist who can make the Potterian moves to argue that the universe caused itself and so does not need a divine explanation. For more on whether the universe could cause itself to exist, see my article "Could the Universe Cause itself to Exist?" Philosophy 75 (2000), pp. 604-612.