You might find this old thread interesting : https://thephilosophyforum.com/discussion/1308/aphantasia-and-p-zombies/p1

Dennett is definitely a zombie created by the blind process of natural selection.

His consciousness is an illusion, born of competing neural circuitry.

Around 11:26 Dennett starts talking about color (pigment). He says there's no role for a property like pigment other than the light hitting the retina and activating cones. But there are brain states which represent to the perceiver the property of pigment. The interviewer says that's the difference between having a phenomenal quality of color (blue) instantiated by his brain and having the quality of blue represented by his brain. Dennett agrees.

I don't understand the difference. We still have the experience of the blue sky (or blue door at this point in the conversation). Dennett is replacing talk of the phenomenal experience with talk of brain states. That's just a semantic move.

So if you don't like the implications of a particular philosophical argument, just change the words used to avoid those implications! If only Chalmers had realized he could have used different words, he could have remained a good physicalist.

This question really ties people up in knots. I think a big part of the problem is language - perhaps there aren't good words for the concepts involved. We seem to be accustomed, perhaps even encultured to the idea that we actually do see things in a sort of Cartesian Theatre. Very hard to shake I guess.

Personally, I agree with Dennett generally and *think* I follow his reasoning, but the language is always confusing; at least it is to me.

But to me, a conscious being, it is clear that after subtracting all these things, you are still left with the phenomenal experience of blue — hypericin

Are you? What IS the phenomenal experience of blue? I suspect nothing at all, beyond the distinctions it tokens. Blue just is what it is for your brain to be in a particular discriminatory state. As long as we agree on the distinctions, then as far as I can see we have had a "blue experience". There isn't anything beyond that, so talk of the phenomenal quality of blue is, I believe, misleading.

Let me offer a thought experiment. Perhaps I simply don't get it, but here's how I think about it. If the world were entirely blue and the only discriminations we could make related to say shadows and lines and so on, such that we were still able to distinguish shapes and distances and so on, what could we say about blue? What would be our phenomenal experience of blue? It seems to me that we wouldn't be able to say anything, that the phenomenal experience of our perception of blue would lack any particular quality. The qualities we could talk about - the qualia of experience - would be shape, distance, shade and so on. I don't think blue itself would - indeed, could - feature in our description of the feeling of perception.

If that's the case, I think the same thing applies even in the world we have. While colours seem to exist as genuine qualities with some colour-like property, I think we are mistaken. Really the only properties are those which accrue from discrimination.

Discrimination seems to be a fundamental process before we can have behaviour into the world; only things that we can discriminate can be incorporated into behavioural routines. Colour as some ineffable deeply personal quality isn't required.

So in answer to the question, no, I don't think Dennett is a p-zombie. Nevertheless, if not experiencing genuine phenomenal qualia is the definition of a p-zombie, then we are all p-zombies.

What IS the phenomenal experience of blue? I suspect nothing at all, beyond the distinctions it tokens. — Graeme M

A-Ha! Another Zombie shambles forth from the shadows! :P

Again, I am confronted by three possibilities:

1: I'm not getting it.
Always an option, and here the most appealing and interesting one to me. I *almost* want to follow your reasoning. The notion that qualia *are* the "distinctions they token" (I like that). But at the end, this thought crashes against the bedrock of qualia.

2: You're not getting it.
Always a salient possibility on philosophy forums. You have philosophically blinded yourself to what is obvious. The least interesting option, and IMO the most likely.

3: You are a zombie.
Eerie, sad, somewhat terrifying. The world as divided into the souled and soulless. It would make for great sci-fi. But could it be real?
The article and thread linked by @csalisbury is fascinating. There are a class of people who either:
a. Lack the mental machinery for visualization. Sure, the brain is deeply flexible and can compensate for much, but wouldn't this be crippling? For instance, in driving?
b. *Possess* this machinery, but are Zombies wrt it! And if we open that door... what if some of us are zombies to all of it!

A few questions:
There is a common thought experiement: suppose my experience of blue is your experience of red. This seems consistent and plausible. But in your view, the distinction is meaningless: we both discriminate, so there can be no difference. But why is this thought experiment so compelling?

For you, the problem of building a machine with qualia is trivial: it just has to discriminate. So if I code up something with an arduino, BASIC, and a color sensor, is that thing experiencing qualia? Seems absurd, no?

Let me offer a thought experiment. — Graeme M

If you were to plop me, a creature evolved in this colorful world, into that one, I would no doubt experience everything as blue. Perhaps that would fade over years. Natives of that world would have no experience nor concept of color, and would be baffled when I tried to communicate this chromatic monotony to them.

Colour as some ineffable deeply personal quality isn't required. — Graeme M

That seeming not-required is part of the mystery!

Are you? What IS the phenomenal experience of blue? I suspect nothing at all, beyond the distinctions it tokens. Blue just is what it is for your brain to be in a particular discriminatory state. — Graeme M

Would you say the same thing for pain or pleasure?

Let's say you're driving down a familiar road and you go into autopilot as you day dream. Now, your brain is still discriminating the steering wheel, gas pedal, lines on the road and anything else relevant for keeping the car on the road. But you're having a conscious experience of imagining something else entirely. How does that work on Dennett's account?

The article and thread linked by csalisbury is fascinating. — hypericin

I haven't read that thread - I have little time to spare so may not get to it for a while. I should, it seems.

suppose my experience of blue is your experience of red. — hypericin

On my view, this question cannot be posed. There isn't anything that is an experience of red such that we could say it is your blue. It's meaningless. If you can respond consistently to a colour that you call red and so do I, that is what red is. Consider that on this thinking, the phenomenal aspect of red (which I hope we agree is "that" particular experience which is always the same when I look at a red rose or a swatch of red) doesn't even need to be the same day to day. As long as we discriminate, that's it. If today the phenomenal aspect has a particular quality, then we'd recall all previous examples as being the same (I am not saying this really happens, merely trying to illustrate that the phenomenal aspect doesn't have to have any actual consistency over time - all that needs to be consistent is the discrimination so that behaviour is consistent).

So if I code up something with an arduino, BASIC, and a color sensor, is that thing experiencing qualia? Seems absurd, no? — hypericin

I can't answer that, I am not proposing any mechanism for how we make said discriminations and think we are experiencing red. But theoretically at least, yes (I'd have to add a lot more to explain that suggestion, but I am agreeing that in essence to discriminate in the right way mechanically is to experience red).

If you were to plop me, a creature evolved in this colorful world, into that one, I would no doubt experience everything as blue. Perhaps that would fade over years. Natives of that world would have no experience nor concept of color, and would be baffled when I tried to communicate this chromatic monotony to them. — hypericin

That isn't quite what I am saying. Of course you would experience the world as "blue", that is, you'd have a concept of the colour blue that you could use to describe your experience of this world. But that is an evolved capacity because you came from a world where discrimination supplies a fitness advantage for your species. Any creature of the monotonously blue world probably would not.

That said, my main point is to try to tease out what it is you can say about blue. Can you tell me anything about blue that doesn't depend on using a blue object to describe it? "The sky is blue" isn't telling me about blue, it's telling me that I can distinguish between the sky and the sand.

Would you say the same thing for pain or pleasure? — Marchesk

Yes.

Let's say you're driving down a familiar road and you go into autopilot as you day dream. Now, your brain is still discriminating the steering wheel, gas pedal road and anything else relevant for keeping the car on the road. But you're having a conscious experience of imagining something else entirely. How does that work on Dennett's account? — Marchesk

I'm not sure about Dennett's account of this, I haven't read much of his. Just enough to get the essential concept (I think). My personal answer is to explain this as an outcome of memory. I think that while Dennett dismisses both the Stalinesque and Orwellian hypotheses, I'd stick to the Stalinesque explanation. This is because I do not think we experience immediate brain processes, rather what we take to be everyday experience is the memory of experience. So we do in effect still "experience" (sorry, really poor words to describe what I have in mind) driving because we have devoted some attentional resources to it, but as long as nothing particularly slaient occurs to allocate more attentional resources, what will be written to memory in order to create the narrative of experience will be what I was thinking about (I suggest there is a threshold for attentional resouces that determines what we actually recall experiencing). So "consciousness" is in effect memory, which is why the Stalinesque hypothesis fits best. Still, the actual immediate processing is probably something like Dennett's multiple drafts concept.

So in answer to the question, no, I don't think Dennett is a p-zombie. Nevertheless, if not experiencing genuine phenomenal qualia is the definition of a p-zombie, then we are all p-zombies. — Graeme M

You certainly do philosophy like a p-zombie!

I actually felt sorry for him! This sounds exactly like a machine figuring out that this whole consciousness thing was just something it was programmed to espouse. But to me, a conscious being, it is clear that after subtracting all these things, you are still left with the phenomenal experience of blue.

Am I missing something fundamental?
Could Dennett be that confused?
Or, is he a Zombie? Or, as a commenter on youtube put it, a NPC? — hypericin

If you are conscious, then where do you draw the line on being conscious? Is your dog conscious? Is it fully, somewhat conscious or not at all? How about a more simple life form? And if you draw somewhere the line between being counscious or not, what are according to you those defining characters to be conscious?

Perhaps answering those questions might make you understand his point better, even if you disagree with them.

Since consciousness is internal, not observable, I cannot answer that. I can only infer. I think my dog is conscious. But lacking first hand experience, that is all I can say.

There isn't anything that is an experience of red such that we could say it is your blue. It's meaningless... the phenomenal aspect of red... — Graeme M

But my "phenomenal aspect of red" is exactly that which we could say is your phenomenal aspect of blue.

As long as we discriminate, that's it. — Graeme M

So if "that's it", and a robot can sort red and blue cards as well as you, must the robot have the same experience?

If today the phenomenal aspect has a particular quality, then we'd recall all previous examples as being the same — Graeme M

Why do you believe this? Why wouldn't your memories of previous phenomenal experience remain intact?

Of course you would experience the world as "blue", that is, you'd have a concept of the colour blue that you could use to describe your experience of this world. — Graeme M

You are equating two things with a verbal equals sign that are entirely separate : "experience of the world", and "concept used to describe your experience". The fact that this distinction seems to elude you makes me suspect that you are, in fact, a p-zombie.

Can you tell me anything about blue that doesn't depend on using a blue object to describe it? — Graeme M

Of course not. I'm just an ape pressing buttons which somehow show you symbols representing grunts which I would grunt at you if you were here. Anything can symbolically represent anything else, nothing better than language. But how on earth, given this very crude system, am I supposed to communicate the actual*content* of blue?? All I can do is symbolically represent it. You are asking way too much of abstracted grunts.

But my "phenomenal aspect of red" is exactly that which we could say is your phenomenal aspect of blue. — hypericin

No, because the phenomenal aspect has no genuine content, at least not in colour terms. What I am trying to get at is that red isn't a specific thing, it's really the state of discrimination. "Red" is a sort of code, if you like. Qualia are codes for discriminations, they bind up a bunch of useful information about the world such that we can distinguish between internal states. Put another way, when you discriminate between red and blue, that's all there is.

So if "that's it", and a robot can sort red and blue cards as well as you, must the robot have the same experience? — hypericin

I don't know that, I'm not proposing the solution to the hard problem. But theoretically yes. I have no idea how much functionality the robot would need to have, and something about memory will be necessary, but fundamentally yes.

Why do you believe this? Why wouldn't your memories of previous phenomenal experience remain intact? — hypericin

Because again, the experience isn't the thing at all. The discrimination is all there is. Your experience, if you like, is a simulation in which the act of perception includes the subjective perspective. Red just is different from blue, so I don't believe you can really say that it has a distinct ongoing continuity. Again, I'm not saying that in practice red today is different from yesterday, just drawing out the point that you couldn't ever know if it was. The operation of memory facilitates the firing of cell assemblies that code for red; that should result in the discrimination of "red". Red today is what red has always been, even if in the past its phenomenal character actually was different.

Of course you would experience the world as "blue", that is, you'd have a concept of the colour blue that you could use to describe your experience of this world.
— Graeme M
You are equating two things with a verbal equals sign that are entirely separate : "experience of the world", and "concept used to describe your experience". The fact that this distinction seems to elude you makes me suspect that you are, in fact, a p-zombie. — hypericin

I'm not sure of your point here, I was largely agreeing with your own statement about the blue world.

But how on earth, given this very crude system, am I supposed to communicate the actual*content* of blue?? All I can do is symbolically represent it. You are asking way too much of abstracted grunts. — hypericin

I am suggesting that there isn't anything you can say about blue because there isn't anything to be said. Colour is a description, not a thing. You use it to describe discriminations.

He's an elderly man just about in his 80s describing a philosophical view, one I don't quite agree with that is to say that can be put into question by another, that clearly went over your head.

As far as your sympathies, I'd save them. Putting aside what vegetative state your mind would likely be in, rather increase to at such a period in life, if even reached, which I doubt. He on the other hand influenced a well known philosopher who influenced him in his career. One I don't particularly care for, nevertheless a feat you will never know.

Why is blue phenomenal to you? His premise was subtracting all previous memory and experience. So, you never saw anything blue before or perhaps any color. There is no understanding of color simply a blank image. What makes blue 'phenomenal' compared to the pitch black of shutting one's eyes? Or any other color for that matter? Because it's lighter? Perhaps this is an intrinsic biological fact. Perhaps not.

Could Dennett be that confused?
Or, is he a Zombie? — hypericin

Based on other arguments I've read of his, this seems plausible.

He should have called it "I am not really writing this".... — Pantagruel

That would be misleading, as Dennett doesn't believe that.

That would be misleading, as Dennett doesn't believe that. — InPitzotl

It would be, "I could not have done other than write this, but I still had a choice!"

Qualia are codes for discriminations, they bind up a bunch of useful information about the world such that we can distinguish between internal states. — Graeme M

This may well be what the a function of what is happening, or the non-experienced facets of what is happening, but it doesn't take away at all from us experiencing them. IOW what you are saying does not contradict the fact that we experience something. It's additional information (you are giving) about what is happening.

Since consciousness is internal, not observable, I cannot answer that. I can only infer. I think my dog is conscious. But lacking first hand experience, that is all I can say. — hypericin

OK, so we can agree that we both think your dog is conscious, at some level at least.

Can we also agree we don't think that a unicellular organism like an amoeba is conscious?

Can we then infer that there some things that make us conscious or leave some organisms to be unconscious? Now, we surely don't know exactly what those are and we can perhaps understand consciousness in a totally wrong way, but excluding that dismal situation, wouldn't it be so that there are things x,y,z... that make something conscious?

What if you see something new that you have no associations for? Even a kitten is fascinated by the world around it and it is all new. We have two kittens at the moment. They relish discovering the new with which they have no associations. Yep, he's a Zombie ok.

If consciousness was only a collection of associations how could you ever become conscious unless you had associations to make and you can't have associations unless you are first conscious? He's definitely Zombified.

Something maybe relevant here: there was an actual experiment done where people wore goggles that flipped their vision upside-down, long enough for them to adapt to that and then be able to do all their normal activities with the upside-down goggles on. When asked at the end whether they were mentally flipping the images right-side-up in their minds and then moving their body normally for a right-side-up world, or changing they way they moved their bodies to suit a world that appeared upside-down, the people said that that distinction did not make any sense to them. Adapting their perception and adapting their behavior seemed like indistinguishable things to them.

This seems to support the notion that phenomenal experiences are not separable from the functionality they serve a role in.

Or, is he a Zombie? — hypericin

If a reputable philosopher like Dennett is a zombie then I'm afraid some of us must be zombies with severe head trauma - dead zombies as paradoxical as that sounds.

Because notoriety means you're intelligent.

This may well be what the a function of what is happening, or the non-experienced facets of what is happening, but it doesn't take away at all from us experiencing them. IOW what you are saying does not contradict the fact that we experience something. It's additional information (you are giving) about what is happening. — Coben

Hard to offer a sensible response to that. I think my position sort of reflects Dennett's, though I really should read his ideas to better grasp where he is coming from. I read Consciousness Explained back in the 90s and didn't understand it then, but have seen references to his views in other books since which is why I *think* my view is similar to his (that is, that my opinion vaguely corresponds with his conceptions).

So, I am not discounting that we experience something. I simply mean that experience is not a kind of thing that happens to "me", experience is an operational space in which the organisation of function/behaviour is schematised. The objects of perception aren't actual objects of representation of an external world, they are metaphors of process. In a real sense, they are descriptions of what is going on internally. So qualia aren't phenomenal objects with phenomenal qualities, they are organisational artifacts. Returning to the matter of red and blue, red doesn't have a phenomenal quality even though we seem to describe it as such, it's actual property if you will is to codify (stand in for) the discriminatory properties of the brain when "triggered" by electromagnetic radiation of particular wavelengths and intensity. We cannot experience light, all we can experience is the way in which cells behave.

Returning to the matter of red and blue, red doesn't have a phenomenal quality even though we seem to describe it as such, it's actual property if you will is to codify (stand in for) the discriminatory properties of the brain when "triggered" by electromagnetic radiation of particular wavelengths and intensity. We cannot experience light, all we can experience is the way in which cells behave. — Graeme M

And it's here that an unbridgeable divide opens up between those who are convinced of the hard problem and those who think it isn't a hard problem.

Either one finds the kind of explanation in your post convincing for explaining consciousness, or one finds it lacking. And yet presumably we all have color experiences.

And it's here that an unbridgeable divide opens up between those who are convinced of the hard problem and those who think it isn't a hard problem.

Either one finds the kind of explanation in your post convincing for explaining consciousness, or one finds it lacking. And yet presumably we all have color experiences. — Marchesk

I don't see it as an unbridgeable divide, more a matter of how we look at the problem. I am not proposing a solution to the hard problem, which is how we can come to have experiences. But restating the problem as not being a representational problem might get us closer.

I am not sure if Dennett's in an anti-representationalist stance. But the moment we choose to believe that what we experience represents the world, we have bought into something like the Cartesian Theatre and our problem becomes how can the actions of cells create a picture that we can see.

I believe that the clearest solution to that is to choose to believe that experience is an operational space - a kind of schematic domain, perhaps even a logical domain. It isn't telling us what the world is like, it's telling us how our operational affordances are organised.

The fact that evolution has optimised our particular operational space such that there is a pretty close approximation between the possible interactions with external objects our brains can propose and the actual interactions permissable by physics (or whatever the "laws" are that govern how objects in the world can interact) fools us a little into thinking we are really looking at (hearing, feeling) the world. But if we think instead that we are experiencing an operational space whose objects are metaphors, we can escape the notion that colours for example are actual qualities.

Does that solve the hard problem? No, we still need to work out the actual mechanism, but I think it gets us a lot closer. We no longer need to think that blue is anything more than the act of discrimination. I think this is sort of what O'Regan gets at in his book "Why Red Doesn't Sound Like A Bell". The feels of experience stand in for the possible interactions available to us, refined by evolution. That's why it probably is the case that the cells that are used to do stuff in visual cortex are much the same as the cells in auditory cortex - the cells themselves aren't the thing, it's the way they code information. The actions of cells aren't creating pictures, they are computing relationships.

So we all have blue experiences but they aren't really phenomenal qualities, no matter how much we like to say they are.

I think of perception as a kind of mathematical transformation, from the raw sensory data received and processed by cells into the purely symbolic domain of qualia. This transformation is done so that higher level computation can be performed within this symbolic domain. Our everyday conscious experience takes place within, or in terms of, this symbolic space. I *think* we are in agreement here, this is more or less a restatement of what you said above.

Where I cannot follow you is your denial that this symbolic domain is experienced by us as " ineffable deeply personal qualit(ies)". They are deeply personal: each of has access to our own symbolic space, and no other. And they are certainly ineffable. Language is just not equipped to transmit them directly, it can only refer to them. Red would be incommunicable to a blind person, and so on.

What is really confusing to me is that you seem to be saying that this first part, which I think we agree with, somehow implies a denial of the second part.

So we all have blue experiences but they aren't really phenomenal qualities, no matter how much we like to say they are. — Graeme M

By "not really phenomenal qualities", you seem to mean that they are not qualities of the world. I think most here would agree, they are contrivances of our minds. But nonetheless they are phenomenal in the sense of phenomenalism, and in this sense they are real. They are the elementals of our inner lives.

Haha, OK. Way to white knight poor helpless old Dennett. I'll tell you what buddy, I'll spare him my sympathy if you spare him your "help". Really, he's fine, he doesn't need your help, even if it were not worthless. In fact, as a working philosopher, I'm sure he would quite resent this honorary rocking chair you want to place him on. These are not exactly new ideas of his, so I doubly don't understand what his age has to do with anything.

When he talks about the woman with Alzheimer's she is not losing consciousness, she is losing her memory.

Alright alright, no need to get nasty. Perhaps I was mistaken. I assumed a major theme of your chastisement was the manner in which he was speaking rather than the message. His aged inflection, or vocal delays between ideas. Something that would not be uncommon for either of us at such an age

I know nothing of the man nor do I know you. I can reasonably assume you're younger than him. The only thing I'm defending is a principle and the only thing I'm attacking is a philosophy. A simple principle of respecting one's elders and listening to what they have to say, as I'm sure you would appreciate later on. And a philosophy of not writing off others you don't agree with as 'subhuman' especially the elderly and especially by manner of speech and not message.

Defending an intellectual society and attacking degradation to it. As much of a losing and downhill battle it has become. Rather, perhaps PF needs less "let's make fun of this old guy" threads as opposed to "I don't like this guy, I think he's wrong. Here is why using logic..." threads.

I actually felt sorry for him! This sounds exactly like a machine figuring out that this whole consciousness thing was just something it was programmed to espouse. — hypericin

I must admit I did a slight double take the first time I read this:

Sometimes a psychologist's most assiduous accounts of phenomena of mental imagery have the flavor of tracts by impassioned believers in flying saucers. — Goodman: Sights Unseen

... introducing an analysis that concludes, with apparent satisfaction:

The 'image' and the 'picture in the mind' have vanished; mythical inventions have been beneficially excised. — Goodman: Sights Unseen

Could this be a different Nelson Goodman from the Goodman of A Study of Qualities (a qualia construction), and Languages of Art, and this:

After we spend an hour or so at one or another exhibition of abstract painting, everything tends to square off into geometric patches or swirl in circles or weave into textural arabesques, to sharpen into black and white or vibrate with new color consonances and dissonances." — Goodman: Ways of Worldmaking

Or had the same author experienced some philosophical conversion or neurological accident, or both?

Well, no. Understanding our conscious experiences simply doesn't have to mean allowing the most literal interpretation of our customary habits of talking of those experiences: validating, in particular, the ancient (perhaps universal) myth of mental images or "impressions". Understanding the experiences doesn't have to mean supplementing the naturalist's usual menu of physical ingredients with an even more generous menu. It doesn't need to deny the experiences; but neither does it need to accept received notions of their "content" uncritically.

You might find this old thread interesting : https://thephilosophyforum.com/discussion/1308/aphantasia-and-p-zombies/p1 — csalisbury

Here's an account by a man who, at 30 years old, realized that other people could visualize things without seeing them.

https://www.facebook.com/notes/blake-ross/aphantasia-how-it-feels-to-be-blind-in-your-mind/10156834777480504/

He never could, and was unaware that anybody else could. He thought that phrases like 'mind's eye,' were figures of speech.

The medical term for this condition is called aphantasia. — The Great Whatever

Yeah, maybe... but as with alleged condition synaesthesia I suspect that the ready defining and near-pathologising merely reflect the dire state of our understanding of thought processes in all their normal variety.

I'm torn. I want to identify as synaesthetic and to describe the visual Mondrians and Pollocks of my musical experiences to anyone prepared to listen; but I'm afraid that that kind of indulgence encourages assumptions about brain function that are far too narrow and too innatist and too modular-ist. Where fans of synaesthesia allege "cross-talk" between folds of cortex (so what?) I prefer this kind of talk:

How our lookings at pictures and our listenings to music inform what we encounter later and elsewhere is integral to them as cognitive. Music can inform perception not only of other sounds but also of the rhythms and patterns of what we see. Such cross-transference of structural properties seems to me a basic and important aspect of learning, not merely a matter for novel experimentation by composers, dancers, and painters. — Goodman: Languages of Art

(My emphasis.)

My issue with "aphantasia" is roughly the converse of this. If the invention of "synaesthesia" betrays our poor grasp of the potential variety of human cognition, the even newer invention might just be a symptom of our over-readiness to indulge the myth of mental images uncritically.

The author is admirably insightful about this objection, though, so we can be fairly sure there is more to his... well, condition. He pretty fairly considers (and rejects) what might have been my objection: that he wasn't ever deficient in a common faculty, merely less given to the prevailing but wrong folk-psychology of it. Even so, one wants to know more detail. Which it links to. So thanks for sharing. (I notice my thanks here are directed to a banned member. :gasp: Oh well.)

I am not sure if Dennett's is an anti-representationalist stance. — Graeme M

I express the same uncertainty here: https://thephilosophyforum.com/discussion/comment/390575 (where there are interesting links on the topic).