Tree and Scarecrow
Suppose I point out a certain tree in the distance to Dale and remark upon its strange shape. I say, "That tree has a strange shape." Dale responds, "That's not a tree; that's a scarecrow!" Suppose we are looking at the same thing, a physical thing that exists in the external world independently of us. But what I take to be a tree, Dale takes to be a scarecrow. Suppose further that the thing in the external world, whatever it is, is the salient cause of our having our respective visual experiences. Are we referring to the same thing? The cause of the visual experiences is the same, but are the referents of our demonstrative phrases the same? Could we say that the referents are the same because the cause is the same?
If this makes sense, then perhaps we can apply it to the 'same God?' problem.
'Same cause, same referent' implies that the cause of my tokening of 'That tree' is its referent. It implies that we can account for successful reference in terms of physical causation. The idea is that what makes my use of 'that tree' successfully refer to an existing tree, this particular tree, and not to anything else is the tree's causing of my use of the phrase, and if not the tree itself, then some physical events involving the tree.
But the notion of salience causes trouble for this causal account of reference. What make a causal factor salient? What makes it jump out from all the other causal factors to assume the status of 'the cause'? (Salire, Latin, to jump.) After all, there are many causal factors involved in any instance of causation. Can we account for reference causally without surreptitiously presupposing irreducibly intentional and referential notions? Successful reference picks out its object from others. It gets to an existing object, and to the right object. Causation might not be up to this task. I shall argue that it is not.
We often in ordinary English speak of 'the cause' of some event, a myocardial infarction say, even though there are many contributing factors: bad diet, lack of exercise, hypertension, cigarette smoking, high stress job, an episode of snow-shoveling. Which of these will be adjudged 'the cause' is context- and interest-relative. A physician who gets a kick-back from a pharmaceutical concern will point to hypertension, perhaps, so that he can prescribe anangiotensin-converting enzyme inhibitor, while the man's wife might say that it was the snow shoveling that did him in. A liberal might say that the heart attack was caused by smoking.
Or suppose a short-circuit is cited as 'the cause' of a fire. In terms of fundamental physics, the whole state of the world at time determines its state at subsequent times. At this level, a short-circuit and the power's being on are equally causal in respect of a fire. Our saying that the short-circuit caused the fire, not the power's being on, simply advertises the fact that for us the latter is the normal and desired state of things, the state we have an interest in maintaining, and that the former is the opposite. Desire and interest are of course intentional notions: to desire is to desire something; to be interested is to be interested in something.
What these examples show is that there is an ordinary-language use of 'cause' which is context-sensitive and interest-relative. The ordinary notion of cause, then, resting as it does on our interests and desires, presupposes intentional notions. I cannot be interested in or desire something unless I am conscious of it. And I cannot adjudge one state of affairs as normal and the other as abnormal unless I have interests and desires.
In the case of my tokening of 'that tree,' what justifies us in saying that it is the tree that causes the tokening as opposed the total set of causal conditions including sunlight, my corrective lenses, my not having ingested LSD, the absence of smoke and fog, the proper functioning of my visual cortex, etc.? How is it that we select the tree as 'the cause'? And what about this selecting? It cannot be accounted for in terms of physical causation. The tree does not select itself as salient cause. We select it. But then selecting is an intentional performance. So intentionality, which underpins both mental and linguistic reference, comes back in through the back door.
The upshot is that an account of successful reference in terms of causation is viciously circular. What makes 'that tree' as tokened by me here and now refer to the tree in front of me? It cannot be the total cause of the tokening which includes all sorts of causal factors other than tree such as light and the absence of fog. It must be the salient cause. To select this salient cause from the among the various casual factors is to engage in an intentional performance. So reference presupposes intentionality and cannot be accounted for in non-intentional, purely causal, terms. Otherwise you move in an explanatory cricle of embarrassingly short diameter.
The point could be put as follows: I must already (logically speaking) have achieved reference to the tree in a noncausal way if I am then to single out the tree as the physical cause of my successful mental and linguistic reference.
Of course, I am not denying that various material and causal factors underpin mental and linguistic reference. What I am maintaining is that these factors are useless when it comes to providing a noncircular account of reference.
Now if causation cannot account for reference, then it cannot account for sameness of reference.
Dale and I are both in perceptual states. These two perceptual states have a common cause. But this common cause cannot be what makes one of our references successful and the other unsuccessful.
Christ and Allah
The above questions are analogs of the 'Same God?' question. Suppose a Christian and a Muslim each has a mystical or religious experience of the same type, that of the Inner Locution. Each cries out in prayer and each 'hears' the inner locution, "I am with you," and a deep peace descends upon him. Each is thankful and expresses his thanks. Suppose God exists and is the source of both of these locutions. But while the Christian may interpret the source of his experience in Trinitarian terms, the Muslim will not. Suppose the Christian takes the One who is answering to be a Person of the Trinity, Christ, while the Muslim takes it to be Allah who is answering. In expressing his thankfulness, the Christian prayerfully addresses Christ while the Muslim prayerfully addresses Allah.
Are Christian and Muslim referring to one and the same divine being? Yes, if the referent is the source/cause of the inner locutions. But this common cause does not select as between Christ and Allah, and so the common cause does not suffice to establish that Christian and Muslim are referring to one and the same divine being.