I think it's more plausible that Dennett has ideological prejudices so powerful that they can overcome any intuitive evidence whatsoever, than that he has experiential defects. But it's interesting to think about how phenomenological differences could lead to theoretical ones, and whether they have in the past. — The Great Whatever

Yes, this was essentially my response to your OP. It's a coherent theoretical idea but I don't really think it is what is actually going on. The idea of phenomenological differences sort of reminds me of the bicameral theory of mind. Literature was analyzed through a historical lens and what was found is that right around the time when Homer would have written his epics we find a distinct change in way language was written. Before then we see lots of command-like writing that is third-person, and not until later do we see actual introspection and the sense of "self".

But it's probably not true, either.

Well, what does imagining a diabetic racist sitting at home reading a cover-less copy of the Lord of the Rings consist of? I can understand having a quasi-visual image of a person reading a book, but the rest isn't so clear. — Michael

I have a pretty vivid visual imagination.

I actually had a specific picture pop up to your question. Clearly it could be different, but I saw something particular.

a priori, I would say we have none. But, then, I do think the hard problem is a real problem, and at the same time I don't think the proposed solutions are satisfactory except insofar that they are intentionally vague and admit of their own ignorance.

I certainly agree that our internal lives differ -- not so radically that it's impossible to discuss, but still different. And that language usage of a certain type seems to mask these differences -- in particular, functionalist-oriented discourse.

But I rather doubt I'm the target of your example, here. I'm the low fruit. ;)

I actually had a specific picture pop up to your question. Clearly it could be different, but I saw something particular. — Moliere

What's the visual property of being a diabetic racist? How could you see that the cover-less book was the Lord of the Rings? What about the image of the location showed it to be that person's home?

Or as another example, what about imagining an invisible man reading an invisible book and imagining an invisible cat sitting on an invisible mat. Surely we can do both, but that in neither case is there any visual imagery. So what, exactly, does this imagining consist of if not have some inner visual imagery? I can certainly understand where Dennett is coming from in saying that this imagining is verbal in nature, that really just involves considering and understanding certain words and phrases.

And if we can imagine invisible cats sitting on invisible mats in a verbal manner then surely we can imagine a visible zebra in a verbal manner.

Once at trial, I called a witness who had suffered severe seizures throughout his life and he was clearly suffering from brain damage. When asked to recollect the automobile accident, he would close his eyes and start reporting slowly what he remembered. It was sort of like he was telling us what he saw in a movie in his head.

So yeah, there are all sorts of ways people visualize, and I'd imagine he sees every zebra stripe.

I saw some show on a guy who perform complex math in his head, and he insisted that he did it by visualizing complex shapes and manipulating them. He proved it by using clay and showing what those shapes looked like with consistency.

Interesting stuff.

I can certainly understand where Dennett is coming from in saying that this imagining is verbal in nature, that really just involves considering and understanding certain words and phrases. — Michael

Did you read my Temple Grandin quote where she said that she does not think verbally at all, but only in pictures? She has the opposite condition of aphantasia.

As for your difficult to visualize examples, someone like Grandin might not be able to visualize it, and would therefore have a hard time understanding what is meant, based on some of the other things she has written.

Why wouldn't people differ in their abilities to visualize and verbalize internally?

Did you read my Temple Grandin quote where she said that she does not think verbally at all, but only in pictures? She has the opposite condition of aphantasia.

As for your difficult to visualize examples, someone like Grandin might not be able to visualize it, and would therefore have a hard time understanding what is meant, based on some of the other things she has written.

Why wouldn't people differ in their abilities to visualize and verbalize internally? — Marchesk

I'm not saying that people don't imagine things visually or must be able to imagine things verbally. I was simply addressing TGW's remark that "What I thought was odd about Dennett's explanation was the bizarrely verbal way he'd put it, as if he himself 'imagines' things by repeating words to himself in his head rather than concocting a quasi-visual image" by providing an example of something that he might be able to imagine but which can't be imagined visually. That might give him a better understanding of Dennett's position.

Of course, if he can only imagine things visually then it won't help.

I took Dennett to be talking about people's capabilities of imagining a horse visually specifically (hence the reference to the fact that the image didn't have any specific number of stripes). I'm not sure where the comment came from, though, so I can't track it down.

If I provided everyone with a picture, gave them 2 minutes to look at it, and then asked questions about what appeared on the picture, I'd assume the majority would get only a small percentage of the items correct, and, the more specific the question, the lower the score. What I'd do is try to remember a list of things from the picture in the hopes that is what would be asked on the test. There might be a very very small number who could actually take a mental picture and then refer back to it then answer questions about it.

There is some controversy about true photographic memory, with some saying it exists only in a small percentage of children (not adults) and some say it doesn't exist at all. https://en.wikipedia.org/wiki/Eidetic_memory.

That is to say, I don't think there's anything at all unusual about those who say they have limited visualization skills because that's the norm. I still contend, though, that the question of whether qualia exist is not addressed by this issue, but, more specifically, it addresses only the question of what is the nature of qualia. It would seem we're all admitting that qualia exists, but we're now asking how it varies from person to person.

That is to say, I don't think there's anything at all unusual about those who say they have limited visualization skills — Hanover

I'm not sure what it means out of context to say people have limited visualization skills – limited as judged by what standard? Obviously people can't literally reproduce visual impressions in their imagination, but no one has ever claimed that.

People with aphantasia seem to have no visualization skills, in the relevant sense.

Now, if there are partial p-zombies demonstrably [...] — The Great Whatever

Ex hypothesi, the existence of p-zombies (partial or not) cannot be demonstrated, because empirically (behaviorally) they are indistinguishable from people. I would think that the capacity to visualize things makes some difference in our behavior, even if it is not easy to tease out. And obviously, in your referenced case the difference did come out, which demonstrably disqualifies the proposed example.

This is more than a quibble. Behaviorists are committed to the idea that exhibiting a particular behavior is a sufficient condition for being conscious, so for them a true p-zombie is an oxymoron.

Good point, I think that's fair. I've been using the term in the wrong way, or at least loosely.

But I still think even the idea that there are people without qualia, who differ in some minimal functional way from those who do, is still one people rule out a priori.

Behaviorists are committed to the idea that exhibiting a particular behavior is a sufficient condition for being conscious, so for them a true p-zombie is an oxymoron. — SophistiCat

Isn't that the same thing as redefining consciousness? Or are behaviorists merely claiming that certain behaviors are indication of consciousness? That you can't have a conscious organism without some resulting behavior, thus p-zombies are impossible? That it would make no sense for a p-zombie philosopher to be discussing qualia.

One should note that not all behavior is conscious, that machines can be made to mock some conscious behavior, that we don't agree on what sort of behavior would qualify a non-human animal for being conscious, and we can't tell whether a comatose patient is sometimes conscious. We also can't consistently guess what someone is thinking.

I always thought that "photographic memory" didn't literally imply visual memory, but really accurate memory.

It seems a more accurate use of the word to say that I had a photographic memory if I can precisely itemize every detail of an image, or words of a book without missing anything, then I think this would be called a photographic memory, because of my perfect recollection, not because the mode of my recollection is visual.

Nor do I suppose that really super vivid visual imagination skills necessitates a better memory of anything at all, but just a better ability to represent visual images to oneself, and that is all.

It's a little shocking to discover differences. I have a poor sense of time and I don't have a constant inner voice. It blew my mind to discover people who have those things.

What's assumed is that we're all the same.

I recall hearing part of this NPR show about a woman who went to live with a tribe that used directional greetings. They were always saying what direction they had come from or went to. She tried really hard to become competent at always knowing what direction she was headed. The result was that she began to develop a visual bird's eye sense of direction where she could just visualize where she was at from a viewpoint looking down on things.

I didn't know that was an ability you could develop. That blew my mind.

Isn't that the same thing as redefining consciousness? — Marchesk

They're not redefining consciousness, but claiming that what we refer to by consciousness is just behaviour.

It's similar to the physicalist who might say that what we refer to by consciousness is just electrical activity in the brain.

What's the visual property of being a diabetic racist? How could you see that the cover-less book was the Lord of the Rings? What about the image of the location showed it to be that person's home? — Michael

Having no experience myself, I think that I can authoritatively field this one. There is no inherent meaning in sounds, sensations, images, smells or tastes, so that I think that it doesn't matter the form or mode, they're just used to represent things to ourselves that reside in the understanding. What detail about anyone's house makes it their house? It's simply understood to be their house. Likewise, a coverless book is just understood to be the lord of the rings, and etc.

What's the visual property of being a diabetic racist? — Michael

There is no property for being a diabetic racist. It's not a singular aspect like red or square. It's more like a cultural archetype -- it's not necessary, unique, or fixed, but all the same a visual picture came to me which fit.

How could you see that the cover-less book was the Lord of the Rings? — Michael

I think my response here is similar to my previous response. Visual imagery doesn't have to be unique and differentiated from other books. But an image which fit the words involuntarily still appeared.

Actually, my copy of Lord of the Rings is what came to me, because it is now cover-less, and images from Lord of the Rings too.

What about the image of the location showed it to be that person's home? — Michael

Sitting on a porch.

Or as another example, what about imagining an invisible man reading an invisible book and imagining an invisible cat sitting on an invisible mat. Surely we can do both, but that in neither case is there any visual imagery. — Michael

Honestly, I saw an outline of each of those things -- the visual representation of invisibility.

So what, exactly, does this imagining consist of if not have some inner visual imagery? I can certainly understand where Dennett is coming from in saying that this imagining is verbal in nature, that really just involves considering and understanding certain words and phrases.

And if we can imagine invisible cats sitting on invisible mats in a verbal manner then surely we can imagine a visible zebra in a verbal manner. — Michael

I don't think I'd say there's no such thing as a verbal imagination. I don't think the imagination is strictly visual. I was just noting that the particularity of things doesn't restrict proper visual imagery. The visual imagination doesn't need to map perfectly to the verbal imagination in order for one to have a visual imagin-thing (not sure what to call it) of particularities.

Philosophers talk about whether p-zombies are metaphysically possible, but what a priori grounds do we have for ruling out the possibility that they're actual? — The Great Whatever

It's a good line of thought. But isn't it also the case that to be able to realise there is a gap in experience - like a lack of visual imagery - there must also be the counterfactual contrast ... which is having that image without having to make an effort at imagining?

So the guy with aphantasia both knows he sees his girlfriend vividly when she stands in front of him, and then that contrasts with his efforts to visualise her. What he says is in fact quite detailed and counterfactually phrased:

"When I think about my fiancee there is no image, but I am definitely thinking about her, I know today she has her hair up at the back, she's brunette. But I'm not describing an image I am looking at, I'm remembering features about her, that's the strangest thing and maybe that is a source of some regret."

http://www.bbc.com/news/health-34039054

A p-zombie would have to lack all such psychic contrast. So there would be nothing for its reasoning to latch on to.

Aphantasia is therefore no more evidence for p-zombies than other irregularities of neurology, like blindness, dyslexia or other lacks which we don't treat as philosophically puzzling. We accept biological variation as causal of neuro-atypicality as there is no grounds to question that.

And in fact that is the strong argument against p-zombies. Can we really imagine a neuro-typical body that is doing all that "information processing" and it not feeling like something? What actually warrants that belief apart from an ability to ignore facts like aphantasia as indeed another of the many demonstrations of the exact correlation between biological structure and experiential reports.

Aphantasia is actually fine-grain evidence for the non-existence of p-zombies as it takes the causal connection between neurology and phenomenology to another level - at least it will once we can check theories that it is all to do with the functional top-down connections needed to drive the primary visual cortex to highly vivid states of perceptual impression, or whatever the case turns out to be.

So p-zombie theory has to posit that a neurotypical person could completely lack neurotypical phenomenology. Anything less than that is a cop-out. And a physicalist theory only has to admit that it doesn't have a complete account of phenomenology. It already stands on the ground of having a partial physicalist account in that no-one sees a problem in attributing blindness to a lack of the relevant equipment, or aphantasia now being due to some similar plausible and demonstrable neural lack. Aphantasia becomes simply, at worst, a promise of physicalist explanation still to be cashed out.

Of course, a physicalist can and should also admit that physicalism has its limits. It will remain radically incomplete - there is an epistemic hard problem - once it gets to the point of being unable to raise theoretical counterfactuals. We can't know the unknown unknowns - even if we can suspect they lurk. So what would it be like to experience grue, etc, etc. Explanation generally loses its purchase when we start trying to tackle differences that don't make a difference. And that is true of physicalism also as an explanatory enterprise.

However that is also not a big issue in practice. It certainly isn't any kind of argument for a positive belief in p-zombies. Just as aphantasia is precisely the kind of further fine-grain counterfactuality that argues in favour of physicalism rather than against it.

(But I'm entertained by the point that Dennett might simply be neuroatypical and that might biologically explain the vigour of some of his beliefs. And neuroscience would say we are all atypical anyway - much more phenomenologically unalike than we realise. That in itself ought to be a fact that informs philosophy of mind - likely a very good paper someone ought to write, if it hasn't been already.)

I experience very vivid visual images (particularly when falling asleep, under the influence of psychotropics, or dreaming) until I try to examine them (actually under the influence of hallucinogens I usually can examine them). I know I experience these powerful images because I can remember them; I don't think the argument that they are constructed after the fact is at all plausible, and so does not constitute any reason to doubt that they are indeed experienced.

So, I tend to think that the experience of this kind of life-like visualization is a subconscious process which dissipates under conscious scrutiny, like mist does under strong sunlight.

Actually -- it's worth noting:

James had a health condition wherein insulin would not be produced, and he was a participant in political organizations which promoted the white race. Today he walked around at his apartment reading the most famous fantasy book ever written, with its cover torn off. He had the unusual ability by which he couldn't be known by words, as well.


The verbal imagination can differ from itself, as well. There are various ways to say similar things. And the verbal imagination can craft sentences which negate our ability to understand said sentences too.

This hypnagogic imagery has the usual pedestrian neurological explanation. Falling asleep involves a gating of outside sensation at the level of the brainstem. Suddenly starved of a flow of stimulation, the brain tries to imagine the world that has just gone missing. Hence the common experience of a sudden sense of falling - noticing the absence of the expected sensations of being a body weighed down by gravity in the usual way.

Also part of falling asleep is the internal disconnection that does away with an integrated state of attention feeding a digested view of the world into short-term, then long-term memory. So a shut down of higher executive functions. That is why the dream imagery bubbling up is a series of fragmentary and loosely associative impressions coalescing.

In actual REM dreams, we are physiologically aroused enough in terms of our habits of executive fuction to try and chase a meaning. There is an inner-voice attempt to narratise and give the usual discursive shape to our flow of experience.

But in hypnagogia - that specific instant of falling asleep - there is just the bare dream imagery as the narrative function has to let go of the day. So - once you are primed for its existence and have had some practice at reawakening enough to catch it and fix it retrospectively - it has an even greater naked intensity than partial narratised REM dreams.

So as for waking powers of visualisation, this always has to compete with a flow of incoming sensation. It is thus more the other way round. It is a conscious attentional effort to conjure up such imagery - the kind of narrative daydreams we might entertain ourselves with. But then you can do that even when driving your car in busy traffic - so long as the world is predictable enough to hand that off to your subconscious or habit-level brain to deal with (the basal ganglia-level motor control) while you dwell in private fantasies and mental imagery of "elsewhere".

There is plenty of other neuroscience to explain the phenomenology. It takes about half a second to generate a full strength mental image - that is how long it takes to turn a high-level inkling into a low level fully fleshed out perceptual image. But then the image fades equally fast because all the neurons involved habituate. They "tire" - because it is unnatural in the ecological setting to hold one image fixed in mind if it is not actually functioning as a perceptual expectation about something just about to happen.

Imagery is for predicting the immediate future - what the world is going to be like in the next split second. That is why it feels like an impossible attentional effort to hold the one picture in your mind for much longer without a refresh of some kind, or the switch to a different but related view.

Again, eidetics show that there is considerable neuro-variation. But everything here can be explained in terms of neuro-typical functionality - which is why philosophy of mind can be criticised for getting so easily carried away by the whole p-zombie and explanatory gap debate.

The idea that there is a metaphysical dualistic divide - mind vs matter - can only flourish in a positive ignorance of the neuroscience. That is not to say we have some fully worked out scientific theory of the mind - I'm of course forever pointing out that current mainstream physicalism really needs to understand semiotics to be able to claim any level of completeness. But the ghost in the machine become pretty residual the more you understand the complexity of the "machine" (that is, how the mind/body is not a machine at all).

I don't claim that anything is constructed after the fact.

In Schopenhauer's the art of controversy he says something about it being great if people's head were transparent and you could see their brains. Unlike Phrenology, it is true that people's brains can tell you a lot about them. May not be able to explain consciousness and things, but lots of different characteristic structures have been linked to certain practices, and skills. This is basically what neuroplasticity means, that the structure of the brain can be changed based on the things you're doing. So that, there is a characteristic structure for playing piano, and things like that. As I mentioned with Einstein, he had a big visual cortex, and wasn't as great with language.

I doubt that I have a super vivid visual imagination hiding in the subconscious that I just can't access. I think that it's more likely that I have a small, or even damaged visual cortex, and you have a big and well developed one.

OH baby, your visual cortex is so big, etc. etc.

Lol, it's not the size that matters, but how you use it!

Wasn't the point about visualizing abstract triangles that you'd have to visualize a particular triangle (with certan angles etc) ?

I might be mixing up empiricists tho

They're not redefining consciousness, but claiming that what we refer to by consciousness is just behaviour. — Michael

That's redefining consciousness to be behavior. It's not at all what most people mean by consciousness. Nor is it traditionally what is meant in philosophy.

It's similar to the physicalist who might say that what we refer to by consciousness is just electrical activity in the brain. — Michael

This is again redefining consciousness to mean brain activity. It is not the same meaning, not remotely.

It's an easy way to try and win a debate, though. Just change the meaning of the term under question and claim there's no hard problem. But it's bad philosophy.

As I mentioned with Einstein, he had a big visual cortex, and wasn't as great with language. — Wosret

He was great with language. Just slow to start speaking. And the suggestion is that he had a "well developed" inferior parietal lobe - which chimes well with the idea that this is a high-level area for spatial imagery. So the mathematical ability to manipulate rather abstracted geometric directions in your head.

The opposite would be a poor ability to spatially manipulate. And that seems born out by the fairly recent recognition of dyscalculia as an academic handicap. People can't learn to tell the time or master maths easily, and there is some brain scan evidence to link that to the same part of the brain.

So talking of visual imagination, there would be two broad divisions with their own variation to start with. You have the parietal "where" pathway for all aspects of imagining spatial relations. And then the temporal "what" pathway where object identification takes place and so also the generation of concrete imagery of things. A weakness in one could be associated with a strength in the other. My daughter has dyscalculia and yet has photographic level ability as an artist.

Wasn't the point about visualizing abstract triangles that you'd have to visualize a particular triangle (with certan angles etc) ? — csalisbury

This is another relevant dichotomy of brain design. Abstraction is about being able to forget the concrete details to extract the essence. So if you listen to people like Einstein describe their creative process, they do stress that it does feel like an imageless mental manipulation of pure possibility - a kind of juggling of shapes and relations which aren't specific.

So in one sense, this is a powerful imaginative faculty - to be able to think in a concrete fashion about the juggling of generalities. Instead of picturing a triangle, you have to be able to picture "triangleness". And you have to suppress or shed the literal detail to get there. You have to be able to vividly ignore as much as vividly imagine you could say.

Think also of tip of tongue experiences, or the moment that you know you have cracked some puzzle before you actually spit out the full answer. The brain is divided between its high level abstract conceptions and its low level fleshed out concrete impressions. So just having that "first inkling" where it all clicks into place in an abductive way we know already bound to work out as the solution, already most of the intellectual work is done.

This is why thought can often seem wordless and imageless - we already know where that snap of connections was going to lead and can move on before its gets said in the inner voice, or pictured in the visual cortex. Why dwell on experiencing in an impressionistic way what we feel conceptually secure about?

Though of course, actually slowing to flesh out thought and experience it that way - as even when typing it out as a post and wondering if it still makes as much sense - is pretty important for our thinking to be more that rapid habitual shoot-from-the-hip response.

Thought and consciousness are wonderfully various activities. And again, that complexity maps to known neuroscience and even rational (dialectical) principles.

An unimportant aside but that's how I first got into dichotomies and hierarchies. It just ended up screaming at you from neuroanatomy. It is the logic that shapes the architecture of the brain from the first neuron and its receptive field design.