Having just read Peter Geach's "On Worshipping the Right God" (in God and the Soul, Thoemmes Press, 1994, pp. 100-116, orig. publ. 1969) I was pleased to discover that I had arrived by my own reasoning at some of his conclusions. On Christmas Eve I quoted Michael Rea:
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.
Rea's argument is this:
A. There is exactly one God if and only if all Gods are the same God
B. Everyone who worships a God worships the same God.
But as I pointed out, the state of worship/worshipping is an intentional or object-directed state, and like all such states, not such as to entail the existence of the object of the state. One cannot worship without worshipping something, but it does not follow that the object worshipped exists. So (B) is false. Geach makes the same point in 'formal mode':
It may be thought that since there is only one God to worship, a man who worships a God cannot but worship the true God. But this misconceives the logical character of the the verb 'to worship.' In philosophers' jargon, 'to worship' is an intentional verb. (108)
Exactly right. And so, just as I can shoot at an animal that is not there to be shot at, I can worship a God that is not there to be worshipped.
I put the point in my own 'formal mode' way when I said that 'worships' is not a verb of success.
The possibility of worshipping what does not exist is connected with the question whether 'God' is a logically proper name. Geach rightly argues that "'God' is not a proper name but a descriptive term: it is like 'the Prime Minister' rather than 'Mr. Harold Wilson.'" (108) One of his arguments is similar to one I had given, namely, that God is not known by acquaintance in this life. As Geach puts it, ". . . in this life we know God not as an acquaintance we can name, but by description." (109)
God is therefore relevantly disanalogous to the examples Beckwith and Tuggy gave. Those examples were of things known or knowable by sensory acquaintance here below. Suppose Dale and I are seated at one and the same table. I pound on it and assert "This table is solid oak!" Dale replies, "No, it is not: there is particle board where you can't see." Dale thinks that a disagreement about the properties of a putatively self-same x presupposes, and thus entails, that there really is a self-same x whose properties are in dispute. But that is not the case. Disagreement about the properties of a putatively self-same x is merely logically consistent with there really being a self-same x whose properties are in dispute. In the case of the table, of course, we KNOW that the dispute is about one and the same item. This is because the table is an object of sensory acquaintance: its existence and identity are evident. But it can be different in the case of God with whom we are not sensorily acquainted.
Clearly, a Spinozist and a Thomist are not worshipping one and the same God despite the fact that for both Thomists and Spinozists there is exactly one God. One of them is worshipping what does not exist.
And so it is not at all obvious that Jew, Christian, and Muslim are all worshipping the same God. That, I submit, is crystal-clear. And so those who think that the question has an obvious answer are plainly wrong.
But this is not to say that Jew, Christian, and Muslim are NOT worshipping one and the same God. That is much more difficult question.
Do we all agree now?