But if you've ever seen an afterimage, the perceptual evidence seems pretty stacked up in favour of a relational logical form. — jkg20

I don't know... Even if you think of the paradigm of perception as being a relation between a perceiver and an object, something like P(S,0), afterimages aren't really like this, are they? It's not that the perceiver is pointing her perceiving device at a different object; it's that the device itself has a temporary modification. To get someone to see an afterimage, you even tell them to look at a blank wall or something. It's just there's an overlay now. So the perceiving relation might take an optional parameter, something like P(S, O, [X]), where X is some object you have an afterimage of. You could think of the X not as an object you're seeing at all, but as an indicator that you're seeing the wall in a special, X-modified way. Not much different from looking through a filter of some kind.

It could be that the initial impulse for the adverbial account is to capture the difference between changes to what you're looking at and changes to the equipment you look with, changes in what you see, on the one hand, versus changes in how you see, on the other. I don't know how well it works, or whether it can reasonably be extended to a general account, but a distinction like that seems reasonable and motivated to me.

If we see something blurred as opposed to clearly, or as you suggest through a filter of some kind, I admit there is a good deal of motivation - independently of any apriori convictions about materialism/idealism - for thinking that the difference is not in the "objects of vision" but rather the viewing equipment. So there is certainly something in what you say. However, in regards to afterimages, I'm not so sure that this motivation applies, or even if it does, that it trumps the "act-object" view of what is going on. After all, you mention that to get someone to see an afterimage we might ask them to look at the same wall they were looking at earlier, but now there is an overlay, okay - so what's "an overlay" other than an object of vision distinct from the wall? Adverbialism, as I understand it - and admittedly, I'm perhaps not being very charitable - is simply an attempt to brush overt commitments to such strange "mind-dependent" objects of vision under a carpet of language, in the hope that no-one tries to flatten out the bumps. I suppose the point I am advocating is that it fails phenomenologically, and because it fails phenomenologically, that gives us some evidence for supposing that it is false. Suppose, for instance, you track an afterimage across a room, on the analysis you are proposing, it would seem we would no longer be keeping an eye on one thing, it would have to be interpreted as seeing a lot of different things modified in similar ways, but splitting it up like that might in the end fail to do justice to the phenomenology of tracking.

Anyway, perhaps there is a more basic/general question to address before asking questions about afterimages specifically, and that is "what are the objects of vision?". Berkeley and others after him (realists and materialsits alike) took the basic building blocks of perceptual objects to be instances of visible properties - specifically colour and shape. If that is right, the question would be "when we see afterimages are there instances of visible properties that are objects of vision or not"? If there is an instance of redness when I see a red afterimage - regardless of the logical form we finally give to afterimage statements - then I think questions with consequences for realism / directness/indirectness of perception would still have to be answered about those instances.

I think that there's a fundamental problem in suggesting that the grammar of one's statements entails one ontology or another. This is where Wittgenstein's remarks on language play an important role.

If you want to argue for direct realism, indirect realism, idealism, or something else then that's fine, but to do so with reference to the allegedly 'competing' statements "John saw a red, round afterimage" and "John sensed redly and roundly" seems misplaced. You might as well argue over what the referent of "it" is in "it is raining".

If you want to argue for direct realism, indirect realism, idealism, or something else then that's fine, but to do so with reference to the allegedly 'competing' statements "John saw a red, round afterimage" and "John sensed redly and roundly" seems misplaced.

I completely agree - if you want to argue for idealism then you need to do a lot more work, and that's not what I'm doing here. The main idea I'm trying to explore in this thread is just that adverbialism does not provide realists with a means of diffusing the idealist's position, and that ultimately it is just a linguistic sleight of hand which leaves the main issue untouched. Wittgenstein's remark about "it is raining" was supposed to show that not every use of a pronoun requires that there be something referred to by that term, and comes (if I remember correctly) in the context of discussing what "I" refers to in statements like "I feel pain". He may (or may not) have been right about that, but I'm not sure what its relevance is to the idealist's position that "John saw an afterimage" and "John saw a football" are statements made true in exactly the same kind of way: i.e. by the existence of objects of vision. When we ask "what does 'it' refer to in "it is raining"?" it is indeed a strange question, one we would not naturally ask and to which no answer seems clear and perhaps none can be given, and to that extent the question may have no meaning. But "what is an afterimage?" is a question that makes perfect sense, which can be investigated and to which different answers can and continue to be given.

He may (or may not) have been right about that, but I'm not sure what its relevance is to the idealist's position that "John saw an afterimage" and "John saw a football" are statements made true in exactly the same kind of way: i.e. by the existence of objects of vision. — jkg20

My point was that the grammar of the statement "John saw a red, round afterimage" doesn't imply that we are "treating afterimages as actual things with such features" (and that adverbialism doesn't avoid this by using the statement "John sensed redly and roundly"), just as the grammar of the statement "it is raining" doesn't imply that there's some thing which performs the activity of raining. The statements are just how we speak, nothing more.

Words are one type of thing and whether or not there are (external) things which act as objects of perception is another thing, and so to look at the former to make sense of the latter is a mistaken endeavour.

But "what is an afterimage?" is a question that makes perfect sense, which can be investigated and to which different answers can and continue to be given. — jkg20

I agree, but it's not a question that can be answered by examining grammar.

It's also why I think the oft-quoted "'the cat is on the mat' is true iff the cat is in the mat" as used as a defence of realism is misguided. Disquotiation doesn't say anything about ontology; just about the grammar of truth-predication.

My point was that the grammar of the statement "John saw a red, round afterimage" doesn't imply that we are "treating afterimages as actual things with such features" (and that adverbialism doesn't avoid this by using the statement "John sensed redly and roundly"), just as the grammar of the statement "it is raining" doesn't imply that there's some thing which performs the activity of raining. The statements are just how we speak, nothing more.

I agree, to some extent at least. It's the adverbialist that puts the emphasis on logical form and I introduced the problem in an "adverbialist-friendly" manner. But as far as I'm concerned it's really the phenomenology that points to afterimages being objects of vision, and the adverbialist is ignoring the phenomenology.

I've never come across arguments that deflationism/disquotationalism supports realism rather than idealism (or anti-realism of any kind). What/who would be a good example of that kind of position?

I've never come across arguments that deflationism/disquotationalism supports realism rather than idealism (or anti-realism of any kind). What/who would be a good example of that kind of position? — jkg20

It comes up on here occasionally. One person (the idealist) will say that "the cat is on the mat" is true iff we have a certain kind of experience and another (the realist) will respond by saying that "the cat is on the mat" is true iff the cat is on the mat, as if that somehow contradicts the idealist.

Which it clear doesn't :wink: OK, I thought maybe there was a known argument that takes deflationism as a premise and reaches realism as a conclusion by way of some more sophisticated chain of inference.