Monday, January 24, 2011

Metaphysical reasoning

I just noticed an argument by Bill Vallicella that is a perfect example of the ‘metaphysical reasoning’ that I commented on earlier. He writes

There is a clear sense in which every intentional mental state 'takes an
accusative,' 'is of or about an object.' That object could be called the
intentional object. Accordingly, whether I want a three-headed dog or a
one-headed dog, my wanting has an intentional object.
In other words, he clearly regards as valid the inference from (A) to (B) below:

(A) Bill wants a three-headed dog
(B) Bill’s wanting has an intentional object

This is the crucial step in the argument for ‘intentional object’, and it is clearly faulty. Look at the verbs of sentences (A) and (B). Sentence (A) contains the verb ‘wants’. Sentence (B) contains the verb ‘has’. These are different types of verb, and of course the whole problem began with important logical differences between ‘intentional’ verbs such as ‘wants’, ‘thinks about’, ‘is looking for’ and so on, and other verbs such as ‘owns’, ‘works in’, ‘is to the left of’ and so on. Both realist and nominalist agree that ‘Bill wants a three-headed dog’ is consistent with ‘no dog is three-headed’, and therefore does not imply ‘some dog is three-headed’. And they also agree that ‘Bill lives in a house in the desert’ is inconsistent with ‘no house is in the desert’, and therefore does imply ‘some house is in the desert’.

With that agreed, it is unreasonable for the realist to argue from (A) to (B). The verb ‘has’, which connects ‘Bill’s wanting’ and ‘an intentional object’ doesn’t look like an intentional verb. It is a verb of posession like ‘owns’. Thus it is inconsistent with ‘no object is intentional’, and therefore does imply ‘some object is intentional’. Similarly for the argument given by Peter Lupu where he says “Bill defines whatever it is that they [intentional states] are about, or are of, or directed towards by the term 'intentional object'. “ But the sentence

(B’) Bill’s wanting is directed towards an object

also contains a verb ‘is directed towards’ which is not obviously an intentional verb. The nominalist will challenge both of these inferences, on the grounds that (A) does not imply the existence of anything at all apart from Bill and his mental states, whereas (B) and (B’) do imply the existence of something apart from Bill’s and his mental states, and on the grounds that ‘whatever is implied by the consequent is implied by the antecedent’.

Note that this nominalist line of reasoning is purely logical. It starts with something that both sides agree on – namely that the logic on ‘intentional verbs’ is different from ‘non-intentional verbs’, and that what the logical properties of ‘wants’ may be different from the logical properties of ‘has’. Then the nominalist simply points out that a crucial step in the realist’s argument depends on the assumptiont that the logical properties of ‘wants’ are not different from the logical properties of ‘has’.

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6 Comments:

Blogger David Brightly said...

This is the clearest presentation of the argument so far. I can see why you say that Bill and Peter have not understood.

But...Bill asks us to imagine an x such that

x is a woman
x is naked
x is holding Maimonides
etc

We appear to be making predications of something and these predications seem causally to influence my imagining (as Bill knew they would). Something more is happening than merely having these predications 'before the mind', or would the Ockhamist deny this? How does the account go on from here?

3:48 pm  
Blogger Edward Ockham said...

I didn't understand Bill's argument at all. If I turn the linguistics tap of completely, and try to visualise, all I get is mental images. These are not intentional, they are just, well images.

On your second point, that we appear to be making predications of something, I don't really understand. Consider

Bill thinks that some x is a woman and x is naked etc.

Then there is clearly predication going on, but it is all within the scope of the quantifier.

S thinks that Ex Fx

does not imply

Ex S thinks that Fx

9:14 pm  
Blogger David Brightly said...

Don't images pass the intentionality test? 'Bill sees a pink rabbit' doesn't imply 'there is a pink rabbit'. Or even 'This Escher drawing is of an impossible object'.

Regarding predications, they seem to be of the image or conjectured entity.

Bill sees a rabbit. It's pink.
Jake seeks a goldmine. It's in Surrey.

There is a sense in which the 'is pink' and 'is in Surrey' predications are not of the rabbit or the goldmine at all, but are further characterisations of the subject's mental state, as in your earlier 'Jake is seeking goldmine-in-surrey-ly'.

10:39 am  
Blogger Edward Ockham said...

>>'Bill sees a pink rabbit' doesn't imply 'there is a pink rabbit'.

Surely it does. 'Bill is hallucinating a pink rabbit' doesn’t, though.

>>Or even 'This Escher drawing is of an impossible object'.

Agree.

>>Regarding predications, they seem to be of the image or conjectured entity.
Bill sees a rabbit. It's pink.
Jake seeks a goldmine. It's in Surrey.
There is a sense in which the 'is pink' and 'is in Surrey' predications are not of the rabbit or the goldmine at all, but are further characterisations of the subject's mental state, as in your earlier 'Jake is seeking goldmine-in-surrey-ly'.
>>

More later on this. The use of pronouns or names to refer back to subjects introduced by means of general existential assertions is a famous unsolved problem in philosophy of language.

1:18 pm  
Blogger David Brightly said...

>>Surely it does.
Well, there's an ambiguity, isn't there? A psychologist conducting experiments into visual illusions would ask a subject 'tell me what you see' rather than 'tell me what you hallucinate'. And we see the straw as bent though we know it's straight. Bill and I are emphasising the phenomenology.

Re the unsolved problem. Yes, but the subjects in these examples, the rabbit, the goldmine, aren't introduced under existential quantification. That's the nub of this argument. To get a quantifier we have to rewrite the sentences: 'Bill thinks there is a pink rabbit and he is seeing it.' 'Jake thinks there is a goldmine in Surrey and is seeking it'. Is this the deeper logical structure you hint at?

2:27 pm  
Blogger Edward Ockham said...

>>Is this the deeper logical structure you hint at?

Yes, but it would take me some time to justify it. Geach's example is something like (don't have the paper to hand) "Jack thinks there is a goblin in the shed, and Jackie thinks that he [the goblin] has put a spell on everyone".

The problem is that the pronoun 'he' occurs within the scope of the 'thinks that'. How do you represent those two thoughts in formal logic?

1. Jack thinks that for some x, x is a goblin and x is in the shed. Jackie thinks that ???

You have to make it clear that Jackie is thinking about the 'same' goblin as it were. But you could only do that by quantifying outside the 'that' clause. And if you do, you immediately have existential import.

7:39 pm  

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