Michael Rea, no slouch of a philosopher, makes the following surprising claim in the Huffington Post:
Christians and Muslims have very different beliefs about God; but they agree on this much: there is exactly one God. This common point of agreement is logically equivalent to [the] thesis that all Gods are the same God. In other words, everyone who worships a God worships the same God, no matter how different their views about God might be.
I am having trouble understanding this; perhaps the esteemed members of the MavPhil commentariat can help me. Doesn't Rea's claim succumb to an elementary counterexample?
Suppose there is exactly one God, but that Tom worships a nonexistent God. (Tom is perhaps a Mormon, or a Manichean, or a 'pastafarian.') It would then not be the case that "everyone who worships a God worships the same God." This is because the one existent God cannot be identical to a nonexistent God. Therefore, if there is exactly one God it does not follow that all Gods are the same God. What follows is merely that all existent Gods are the same God. But that is surely trivial. It is as trivial as saying that if I own exactly one house, then all the houses I own are the same house. (It is relevant to point out that if one owns x, then x exists whereas if one desires x, it does not follow that x exists. The relevance will emerge in a moment.)
How is the above trivial truth -- There is exactly one God if and only if all existent Gods are the same God -- supposed to help us with the question whether Christians and Muslims worship the same God? It does not help at all: it may be that the God Muslims worship does not exist while the God Christians worship does exist. Or the other way around.
Surely this is a logically consistent trio of propositions:
The Christian (triune) God exists.
The Muslim (non-triune) God does not exist.
There is exactly one God.
And this one as well:
The Christian (triune) God does not exist.
The Muslim (non-triune) God does exist.
There is exactly one God.
So it could be that while there is, i.e., exists, exactly one God, Christians and Muslims do not worship the same God. It could be that Muslims worship a nonexistent God. Or it could be that Christians worship a nonexistent God. Bear in mind that the one existent God cannot be both triune and not triune. Cannot be: if God is triune, then essentially triune, and if essentially triune, then necessarily triune given that God is a necessary being. The same modal upshot if God is not triune but unitarian.
So What Was Rea Thinking?
That 'worships' is a verb of success? If 'worships' is a verb of success, then Rea's claim is true. To say that 'worships' is a verb of success is to say that it follows from x's worshiping y that both x and y exist. But if Rea assumes that 'worships' is a verb of success, then he simply begs the question. The question is whether Christians and Muslims worship the same God on the assumption that they both hold, namely, that there is exactly one God. To assume that whatever one worships exists is equivalent under the just-named assumption to assuming that the Christian and Muslim must be worshiping the same God. But then the question is begged.
Either 'worships' is a verb of success or it is not. If it is a verb of success, then Rea begs the question. But if he holds that 'worships' is not a verb of success, then he allows the possibility that either the Muslim or the Christian worships a God that does not exist. Ergo, etc.
'Worships' is not Reasonably Viewed as a Verb of Success
'Sees' has both a phenomenological use according to which it is not a verb of success and a use as a verb of success. It is reasonably taken to have both uses. But all I need for present purposes is the point that 'sees' is reasonably used as a verb of success: if I see x, then x exists. On this use of 'see,' one cannot see what does not exist. What's more, it is reasonable to say that there is a causal explanation of my being in a state as of seeing a tree. The explanation is that the state is caused (in part) by the tree which would not be the case if the tree did not exist. Why do I know have a visual experience as of a tree? Becuase there really is a tree that is causing me to have this very experience. This makes some sense.
Does 'worships' have a reasonable use as a verb of success? I say No. God, being a pure spirit, is not given to the senses; nor is he 'giveable' to the senses: he is not a possible object of sinnliche Anschauung in Kantian jargon. We have no direct sensory evidence of the existence of God. So it doesn't make much sense to try to explain my being in a worshipful state by saying that my being in this state is caused by God. Nor does it make much sense to say that my use of 'God' succeeds in referring to God because God caused my use of the name.
Worship as an Intentional (Object-Directed) State
In any case, to worship is to worship something, with no guarantee that the item worshiped exists. In this respect worship is like belief: to believe is to believe something with no guarantee that what one believes is the case. If S knows that p, it follows that p is true; if S believes that p, it does not follow that p is true. The proposition believed may or my not be true without prejudice to one's being in a state of belief.
I say the same is true of worship/worshiping. The object of worship may or may not exist without prejudice to one's being in a worshipful state with respect to it. So it could be that Muslims worship a God that does not exist. How might this come about? It would come about if nothing in reality satisfies the definite description that they associate wth their use of 'Allah' and equivalents. And how could that be? That would be so if the true God is triune.
There are very deep issues here and I am but scratching the surface in bloggity-blog style. But one thing is clear to me: one cannot resolve the question whether Christians and Muslims worship the same God with "a flick of the philosophical wrist" to borrow a cute phrase from Lydia McGrew (my only distaff reader?) who dropped it in an earlier comment thread.
There is no 'quickie' solution here, with all due respect to Michael Rea and Francis Beckwith and Dale Tuggy et al.
It is Christmas Eve. Time to punch the clock. I leave you with a fine rendition of Silver Bells.