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Thursday, November 09, 2006

Chalmers on De Re Epistemic Ascriptions

In "The Foundations of Two-Dimensional Semantics" David Chalmers mentions that it is difficult to make sense of de re epistemic ascriptions. To see what the problem is, consider:

(1) It is a priori that Phosphorus has been visible in the morning.

The proper name in (1) can, via property abstraction, move out of the scope of the a priori operator. Then we get:

(2) Phosphorus is an x such that it is a priori that x has been visible in the morning.

This is the de re reading of (1). The a priori operator operates on some aspect of a sentence that has a variable in it.

The reason it is difficult to make sense of this is that the a priori operator cannot be taken to operate on singular propositions. If it could, then we should expect 'Hesperus is Phosphorus' to be a priori (which, of course, some thinkers do want to argue that it is). It is better to think of the a priori operator as operating on what Chalmers calls the 'primary intension'. The primary intension is (roughly) the possible-world equivalent of a Fregean thought. The problem now is that it is difficult to see what sort of Fregean thought/primary intension could possibly be expressed by the operand sentence in (2), viz. 'x has been visible in the morning'.

It might be suggested that the Fregean sense/primary intension of 'x' is something that can be glossed as 'the bright object in the morning sky'. But that does not seem right. For what is special about the de re reading of a sentence like (1) is that it "gets at" the object directly, as Russell would put it.

An alternative approach would be to say that the primary intension of 'x has been visible in the morning' is contingent and hence not a priori (as 'apriority' is defined in terms of the necessity of the primary intension). This would follow if the primary intension of 'x' is similar to the primary intension of a name whose referent one cannot really describe, even though one can use the name proficiently (by being a link in a causal chain that leads back to the referent). It would follow, then, that even though (1) is true on the de dicto reading, (2) is false. For just like the Fregean element expressed by 'some x has been visible in the morning', the Fregean element expessed by 'x has been visible in the morning' is true at some conceivable scenarios and false at others.

If the latter is correct, then there is an independently interesting lesson to be learned, namely that property abstraction on sentences involving proper names is not simply a trivial move, as sometimes suggested. Property abstraction can make a difference to truth-conditions even for sentences containing no quantified noun phrases.

5 comments:

tristanhaze said...

I think the best response to this problem would be to regard the a priori operator here as being "generalized" - usually the concept of a priority applies to particular thoughts or representations, but one can apply it to thoughts fulfilling a certain condition - for example, representing x as being visible in the morning where x = Phosphorus. The whole sentence could be given a reading such that it comes out true iff all thoughts/representations fulfilling that condition are apriori, or alternatively, iff some are.

By the way, given the background understanding that Chalmers will want to hold that something like (1) is true, a parenthesis '(if it exists)' should probably be appended to 'Phosphorus'. This is what Chalmers does in 'Foundations'. (I mention this because, for a moment there, I thought I'd "found" an objection to Chalmers, namely that (1) is clearly false!)

tristanhaze said...

Sorry to comment again so soon, but I've just been thinking about:

(1*) It is a priori that Hesperus (if it exists) has been visible in the evening.

(Chalmers suggests that 'Hesperus (if it exists) has been visible in the evening' is an 'a priori sentence' on p. 61 of 'Foundations of Two-Dimensional Semantics'. I change your example over from Phosphorus/morning to Hesperus/evening just for the sake of this reference.)

If we found out that, on all those occasions when we were getting acquainted with Hesperus and fixing the reference of 'Hesperus', we were elaborately deceived about the time of day, and that it was really morning, and never evening, would we say that Hesperus didn't exist after all? It seems to me we would not.

This strongly suggests to me that (1*) is false.

If that's right, one lesson would be that 'A-intensions' are harder to articulate (even partially) in general terms than the rough attempts common in writings on the topic would indicate - if indeed this can be done at all.

There seem to be connections here to Kripke's criticisms of descriptivism.

Brit Brogaard said...

Sorry to the delay in replying. I am only now catching up on all my emails. Sure, the "if it exists" clause should be included. I am not sure I understand your second point about 1* being false. Is it because of a special treatment of "evening"?

Tristan Haze said...

No worries about the delay.

I didn't have special treatment of 'evening' in mind - the thought was just that it seems like it could turn out that we have been elaborately deceived about it having been evening when we saw the body we call Hesperus.

That is, it seems like it could turn out empirically that Hesperus exists but has never been visible in the evening. (I know, it's pretty far out, in the way Kripke's cat-robot example is, but that shouldn't matter in principle.)

If that's right, then it's not a priori that Hesperus (if it exists) has been visible in the evening. And that's what (1*) says.

FWIW, shortly after my original comment, I made this suggestion (that 'Hesperus (if it exists) has been visible in the evening' is a posteriori) to David Chalmers, and he took the point.

Brit Brogaard said...

Right. That's interesting. So I declare that the brightest object in the evening sky is to be called 'Hesperus' believing that I am naming an object I see in the evening. Unbeknownst to me, however, an evil demon has had me looking at a bright object (= Venus) in the afternoon and there is no bright object in the evening.

OK, so in that case 'Hesperus (if it exists) is the brightest object in the evening sky' is false, because there is no brightest object in the evening sky.

However, as a matter of fact, there was no evil demon in reality. So, 'Hesperus (if it exists) is a priori true.'

I think this is a bit like saying 'well, scientists could have discovered that water is XYZ here' and if they did, then 'water is H2O' would have been false. As a matter of fact, though, it is true.

Or are you saying that we cannot rule out on a priori grounds that we have been looking at an object in the afternoon all along, that there is no brightest object in the evening sky and that it therefore cannot be ruled out on a priori grounds that 'Hesperus (if it exists) is the brightest object in the evening sky' is false?