(Note: this is cross-posted at my new blog, The Ring of Truth)
Of all the proposals put forward for understanding the structure of the positive case for theism, that by Dallas Willard as he described it in a famous article strikes me as the most plausible. Willard distinguishes his own approach from one which "in one stroke, from one set of true premisses, purports to establish or render plausible the existence of Jehovah, understood by Christians to also be the God and Father of our Lord Jesus Christ." He does not present a series of independent arguments, each of which lead to the same conclusion, the existence of the Christian God. In his view, the evidence for God is built up in stages, where the conclusions at each stage do not serve straightforwardly as premisses for arguments at the next stage. Rather, "what is shown or evidentially supported in the earlier stages only determines a framework of possibilities within which the considerations of the later stages are carried on." He proposes three stages of theistic evidence. The first stage demonstrates that the cause of the physical universe is itself non-physical and unconditioned by anything other than itself. The second stage demonstrates that the cause of the universe has some analogy to human intelligence. The third stage fills in the details about this intelligent, transcendent cause by attending to specific religious and moral experiences in human history.
The conclusion of stage one, that the cause of the physical universe is itself non-physical and self-subsistent, derives from the observation that, "However concrete physical reality is sectioned up, the result will be a state of affairs which owes its being to something other than itself." There are two ways we can see that this is true. The first way is to observe that for any physical thing to exist, certain conditions have to met, which conditions derive from outside itself. For example, in order for a biological cell to exist certain sub-cellular structures had to come together in just the right way. Those other structures and their arrangements comprise the conditions for the existence of the cell. Those structures in turn depend for their existence on certain molecular structures, and so on. It is plausible to claim that every physical thing is conditioned in some way by factors outside itself.
The second way, which Willard focuses on, has to do with the fulfillment of these conditions across time. We observe that "every physical state, no matter how inclusive, has a necessary condition in some specific type of state which immediately precedes it in time and is fully existent prior to the emergence of the state which it conditions." Think of the ignition of a car engine. In order for this to take place the following conditions had to be in place the instant prior to the ignition: a source of voltage had to supply a spark through a functioning spark plug, the cylinder containing a certain amount of fuel had to be pressurized to just the right degree, etc. What do we mean that the triggering state had to be 'fully existent' prior to the emergence of the state we are observing? Well, the triggering state itself had to emerge under certain other conditions before it could bring about the state we are observing, which conditions also had to emerge, etc. If we are observing the collapse of a series of dominos, before the 13th domino collapses the 12th had to collapse, and before the 12th could collapse the 11th had to collapse, etc.
If we follow this example through to its logical conclusion, we have to conclude that any series of physical causes must have a first term if anything is to happen. Otherwise we are forced to imagine an infinite series of causes going back into the infinite past, in which case the conditions of the state we are observing could never be met, as the necessary conditions of those conditions would never 'get to' them. In the domino case, for example, if an infinite number of dominos must fall before the one we are observing can fall, the one we are observing cannot fall because the falling line of dominos will never get to it. Furthermore, the first term must be quite unlike the causes that come after it in that it is self-subsistent, unconditioned by anything else. If it were itself conditioned, then it would not be the first term and we would have to push our investigation back even further. "Thus," Willard concludes, "concrete physical reality implicates a being radically different from itself: a being which, unlike any physical state, is self-existent."
So whether we observe the world in terms of currently existing physical structures whose existence depends on that of underlying structures, or in terms of events each of which depends on the occurrence of previous events, we see that behind all conditioned physical structures and dependent physical events there must be something non-physical (since all physical things are conditioned) and self-existent to serve as the first term in all series of causes and the one unconditioned reality that conditions everything else.
I find this line of argument more compelling than attempts to answer the vague question, "Why is there something rather than nothing?" as if 'nothingness' is the default state and the fact that there is 'something' is a surprise that has to be explained. As Willard points out, the existence of anything at all is only a surprise if we have already assimilated existence to physical existence. Physical things as dependent things are "admittedly always more or less hanging on by the skin of their teeth and inevitably tending toward disintegration." If we have decided ahead of time that only physical things exist or could exist, then we will be puzzled why anything exists at all. But "in general ontology one has to understand that existence is, in general, no more problematic than non-existence. Existence isn't somehow 'harder' or inherently less likely than non-existence." What needs to be explained is how physical things come into being and hold together, not just things in general. The existence of a self-subsistent thing is not surprising or inherently unlikely, and forms the best explanation for the current existence of dependent physical being.
Of course it should be emphasized that this is only stage one of the case for theism, and the conclusion of this line of argument does not take us to the Christian God. Indeed, as C.S. Lewis put it at one point in Mere Christianity, we are not yet within a hundred miles of the Christian God. But the conclusion is nevertheless very significant. In Willard's delightful phrase, we are now dealing with an "ontologically haunted universe." He goes on:
If I am right, there has got to be something more than the physical or 'natural' universe: and something obviously quite different in character-though also essentially related to it, for from this 'something more' the physical universe ultimately derives. If this is established, it is not clear to me that very much of a point is left to atheism, which in the contemporary world surely draws most of its motivation from a desire to tame or naturalize reality-all hope of which is now lost.
It would be wrong to criticize this argument for not filling in the details about this non-physical, self-existent cause, because it never pretended to be able to do so. But at the very least it gets us beyond naturalism, which opens up space for the possibility that the non-physical, self-existence cause of the universe is the Christian God. If naturalism were established, this possibility would not be open. That is why the universe is 'ontologically haunted'.