[The object of conception] is not the image of an animal—it is an animal. I knowPerhaps this is what is driving Bill's argument from the premiss ‘Tom is thinking of something’ to the conclusion ‘Tom’s thinking has an intentional object’? Tom is thinking of unicorn, Tom is thinking of something other than the thought of a unicorn, ergo Tom stands in some 'intentional relation' to some quasi-unicorn, an 'intentional object'.
what it is to conceive an image of an animal, and what it is to conceive an
animal… The thing I conceive is a body of a certain figure and colour, having
life and spontaneous motion. The philosopher says, that the idea is an image of
the animal; but that it has neither body, nor colour, nor life, nor spontaneous
motion. This I am not able to comprehend. (Essays on the Intellectual powers
of man, 4.2, 321-2)
Sadly for Bill, this will not work. If I am thinking of a unicorn, then I have a thought of a unicorn. Thus the two following propositions are broadly equivalent.
(A) Tom is thinking of a unicorn
(B) Tom has the thought of a unicorn
But this still doesn't get the conclusion that Bill wants, namely
(C) Tom's thinking has an intentional object.
For (B) can be true even though there are no unicorns. The verb phrase 'has the thought of' is intentional. But the verb 'has' on its own is non-intentional. 'Tom's thinking has an intentional object' is inconsistent with 'there are no intentional objects'. As I have argued, we cannot argue without other assumptions from a sentence using an intentional verb, to a sentence using a non-intentional verb.
The confusion probably occurs because of the two grammatical accusatives in sentence (B) above. The first is 'the thought of a unicorn', which is the object of the non-intentional verb 'has'. We cannot have an F without there being an F, and so cannot have the thought of a unicorn without there being a thought of a unicorn. The second is 'a unicorn', which is the object of the verb phrase 'has the thought of'. Seeing that the first accusative has a corresponding logical accusative, we are tempted to assume that the second has also. But the second verb phrase is clearly intentional, and so the existence of its grammatical accusative does not justify the existence of any logical accusative.
The fact that there are two grammatical objects in (B) does not justify the conclusion that there are two logical objects. This only follows if the two corresponding verb phrases are non-intentional. But they are not, and so the conclusion does not follow.
* Essays on the Intellectual Powers of Man, Derek Brookes (ed.), University Park: Pennsylvania State University Press, 1785/2002.