This is a response to a guest-post at my friend Dan’s blog by Eric Steinhart.
Here’s a two-part argument for the existence of God meant to defuse some of my colleagues’s concerns. For the purpose of this argument, let’s mean by “God” a necessary being (not necessarily unique) who is not part of the world but who is the sufficient explanation for its existence. The first part tries to establish that the world must have a sufficient cause G that is not the world itself or any part of the world. The second part tries to establish that that G exists necessarily. It isn’t the most elegant argument (in fact, the infinite regress argument in part II might be sufficient to prove the conclusion by itself), but I think it fits the dialectical situation.
- Principle of Sufficient Reason: Every contingent fact has a sufficient explanation.
- It is a contingent fact that the world exists.
- Therefore there must be a sufficient reason why the world exists. (1 and 2)
- No contingent thing can be a sufficient explanation of its own existence.
- Therefore, the world itself cannot be a sufficient explanation of its own existence. (2, 3, 4)
- If the world itself cannot be a sufficient explanation of it’s own existence, then there must be some G, which provides a sufficient explanation of the world’s existence, but which is not itself a part of the world.
- G either exists necessarily or exists contingently.
- Suppose G exists merely contingently.
- Then there must be a sufficient explanation of the existence of G. (1, 8 )
- G’ exists either necessarily or contingently, in which case we would need a G” which would have exist either necessarily or contingently, in which case . . . and so on.
- In order to avoid an infinite regress, there must be some being who exists necessarily.
- Therefore, if G exists contingently, there is some being who exists necessarily. (8-11)
- If G exists necessarily, then there is some being who exists necessarily and is not a part of the world but provides a sufficient explanation of its existence, etc.
- Therefore there is some being who exists necessarily who is not a part of the world, but who provides a sufficient explanation for the existence of the world; i.e. God exists. (7, 12, 13)
In defense of premise 1, I’ll just say (only half-facetiously) that it’s true because Alexander Pruss says so (click through for a link to his 2006 book on the PSR). Earlier, Dan made the psychologistic objection that it is just an accidental feature of the human brain that we are forced to think as if the PSR is true. So, he acknowledges that the PSR is a part of our commonsense reasoning, but wants to say that scientists have uncovered good reasons (quantum mechanical weirdness and the Penrose-Hawking singularity theorems) for doubting the PSR. I don’t think this can be right, so here’s a little subargument (I’m not sure if this is how Pruss does it, b/c I haven’t seen his book).
- 1.a Science can give us good reason for doubting the PSR only if there are some scientific observations that either demonstrate or imply PSR doesn’t hold.
- 1.b If the PSR didn’t hold, we would never be able to trust our scientific observations.
- 1.c Therefore, if the PSR didn’t hold, we wouldn’t be able to trust the observations that purport to show that the PSR doesn’t hold.
1.a is obvious. The PSR isn’t false just because Hawking says so. Science could only provide reasons to think it were false if it were observably false or if it was directly implied by something that was observable.
However, as 1.b, says, the PSR itself is presupposed by the practice of observation. Scientific observation works by observing an event and inferring a cause that explains it. I see a streak of light in a bubble cloud chamber being deflected by a magnetic field and infer that the particle that causes the streak has a magnetic charge. But suppose the PSR is not true. Then my inference could be flat wrong for all I know, because it could be the case that the event of seeing a streak of light in a bubble cloud being deflected by a magnet isn’t caused by anything. So, if the PSR is false, we simply wouldn’t be able to trust any of the inferences we make from observing events. (Note that I’ve chosen this particular example because it involves a quantum event, not just a macroscopic one.)
The conclusion 1.c follows that putative scientific objections to the PSR are self-defeating. So, despite Dan’s psychologistic objections, I think there’s still good reason to hold the PSR.
In premise 2, by “the world” I intend all of the physical stuff in the universe. This would be the premise that Eric (following Bertrand Russell, I suppose) wants to reject. He says:
“As is well-known, you can interpret all the cosmological arguments as just being arguments for the existence of the physical world, rather than for God. Why is there something rather than nothing? Because the totality of physical things necessarily exists.”
I don’t find Eric’s response here terribly persuasive. So here are two subarguments in favor of (2).
First, to say that the physical world is necessary is to say that it is not possible for it not to be. Although controversial, the standard test for possibility is conceivability. If the existence of the world were necessary, then I could no more conceive of the world failing to exist than I could conceive a circle failing to be round. But I can conceive of the world not existing; therefore the world doesn’t not exist necessarily; therefore the world exists contingently.
Second, you can run an argument from the contingency of all of the part of the universe to the contingency of the whole without committing the fallacy of composition just by noting that composition is a fallacy only when the specific structure of the parts contribute to the whole’s having a property P which each individual parts lack. So, it would be committing the fallacy of composition to move from “Neurons are unconscious” and “brains are composed of neurons” to “brains are unconscious” just because it’s precisely the combination or structure of the unconscious parts that make the brain conscious. Individual molecules of water don’t freeze, but collections of molecules of water do freeze because the chemical properties of the individual molecules allow crystalization at temperatures below 0 C.
However, necessity and contingency don’t seem to be that way. How would a combination or structure of non-necessary parts combine to give the totality the property of necessity? It’s utterly unclear. This seems to be a case of validly inferring a property of the whole from the property of the parts. There are other clear cases of when composition isn’t a fallacy. For instance, if every piece of a gold bar is gold, then the whole bar is gold too.
Premise (3) follows from (1) and (2).
Premise (4) says that no contingent thing can be a sufficient explanation of its own existence. This is because one thing that we want in a sufficient explanation is an efficient causal relationship, and it is trivially obvious that things can’t cause themselves. If x is the efficient cause of the existence of y then x must already exist (to do the causing) when y doesn’t (otherwise y wouldn’t already exist and wouldn’t be coming into being at all). Hence, x != y, and so nothing can be both the cause and the effect.
But if the world exists contingently, every contingent fact has a sufficient explanation (that must be something different than itself), then whatever provides a sufficient explanation of the world’s existence must be something different than the world, just as premise 5 says. Let’s call that thing G for the moment.
Now, we get to the second part of the argument, which will try to prove that G is a necessary being (or maybe is caused by a necessary being, if G is Plato’s demiurge, for instance).
(7) is an axiom of modal logic. G exists either necessary or contingent.
(8) is an assumption that G exists contingently to begin a reductio. The strategy here is to show that assuming either conjunct in premise (7) leads to the same conclusion, namely that there must be a necessary being.
(9) Follows from (8) and (1) by modus ponens. If G exists contingently there must be a sufficient explanation for it’s existence (per the PSR) and hence there would have to be some other being G’.
Premises (10) and (11) points out that the explanation of G cannot be an infinite series of contingent beings. This is because infinite regresses cannot provide sufficient explanations. If you say p is true because of r and r is true because of q and q is true because of . . . ad infinitum you would never really have provided me an explanation of why p is true.
In the same vein, G cannot be caused explained by popping for an infinite series of other contingent beings, there has to be some necessary being at the head of the explanatory chain. So, just as (12) says, if G exists merely contingently there still has to be some necessary being. (NB. This necessary being has to be outside the world, and still gets to count as it’s sufficient explanation because causation/explanation is transitive: G is the cause of the world ex hypothesi, so if G’ is the cause of G and G is the cause of W, then G’ is also the cause of W, so G’ != W.)
So, if G exists contingently, there is a necessary being who is outside the world, etc. On the other hand, (13) if G exists necessarily, then there is still a necessary being outside the world, etc., namely G itself. Since those are the only two alternatives and the same conclusion follows either way, it must be true that there is a necessary being which isn’t a part of the world but which provides a sufficient explanation of the existence of the world, which is to say that God exists.