One photon: http://www.latimes.com/science/sciencenow/la-sci-sn-human-eye-photon-20160719-snap-story.html

Also, in order to know that something is an illusion in the first place, you'd need to be able to know what it's really like in contradistinction to what you thought it was like. — Terrapin Station

I don't need to know what you look like to know that a caricature of you isn't what you look like.

You have to know something about the relation of caricatures to something that isn't caricatures. You can't know that if you can't experience what people are really like in contradistinction to caricatures.

And you don't think that the scientific observation that macroscopic objects are collections of waves and particles and fields and whatnot counts as showing that what things are like is different to what things are seen to be with the naked eye?

Why would we be talking about "the naked eye" all of a sudden? Who mentioned that?

What else would we be talking about?

This was what I was talking about. In fact, you quoted me: "Also, in order to know that something is an illusion in the first place, you'd need to be able to know what it's really like in contradistinction to what you thought it was like." My only point was exactly what I typed. I didn't say anything there about "naked eye" versus anything else. It's simply a logical point about knowing that something is an illusion.

And I already addressed that. I don't need to know what you look like to know what a caricature of you is not what you look like.

Yeah, and I addressed that. Then you brought up the "naked eye" phrase and I asked you why, because that didn't have anything to do with anything I had said. Should we DC al Coda?

It has everything to do with what you said. Scientific experimentation has shown that macroscopic objects are collections of particles and waves and fields and whatnot. This is nothing like what I see things to be, and I know this even though I don't know what particles and waves and fields are really like.

If we see things directly there are no illusions. — Barry Etheridge

Also in the case of illusions we see things directly: e.g. optical effects such as refraction, or two lines whose ends make their lengths appear different and so on. Without seeing these things directly there would be no illusion.

The only reason that optical illusions work is that the brain overrides the evidence of our eyes to impose its own expectations upon the image. — Barry Etheridge

In optical illusions it is always the case that something is seen, hence 'optical'. Yet you omit optics and instead pass a figment of brain and expectations for vision. You're on your own.

I knew you'd say that but it is of course you that don't get it. If we see things directly there are no illusions. The only reason that optical illusions work is that the brain overrides the evidence of our eyes to impose its own expectations upon the image. So powerful is this effect that it is impossible to unsee the illusion even when we have full knowledge that it is an illusion. It's not a case of our vision sometimes letting us down through a lack of information. The brain simply does not allow us to see what is there and substitutes its own 'reality' for it.

I think you identify as a realist, so tell me what kind of reality you think is there apart from the kind we can perceive and think about.

It is what a white wall looks like, as it really is, when it is seen through blue shades. — jkop

Sure. And this caricature is what you look like, as you really are, when drawn by a caricaturist. Or this is what a table looks like, as it really is, when your eyes are closed. Or this is what a stick looks like, as it really is, when half submerged in water. Or this is what a photo of a dress looks like, as it really is, to someone who sees it as white and gold.

It's a pretty vacuous account of perception, really.

It is misleading because one does not strip the eye in order to see things as they are. — jkop

If you want to say that how things really are is how they are when we're not looking – i.e. their perception-independent nature – then to see a thing as it really is is to see a thing as it is when we're not looking – i.e. to see its independent nature. This is the notion that people like Hoffman are addressing; namely to point out that this doesn't ever happen. The independent nature of a thing is nothing like its look (or its smell or its taste, and so on).

This is nothing like what I see things to be — Michael

I didn't say anything about your vision per se in my comment.

If we see things directly there are no illusions. — Barry Etheridge

No one has a view that posits that one accurately knows noumena 100% of the time. So any argument based on that idea would be a straw man.

And? You obtain that information using standard research methods other than sight. In the most basic line length illusions for example you simply get out a ruler and measure the lines or in the case of false convergence you measure the angles. But the really significant thing is that armed with the knowledge of the equal length of the lines you still cannot unsee the illusion. You cannot see equal lines even when you know that they are equal.

I think you identify as a realist, so tell me what kind of reality you think is there apart from the kind we can perceive and think about. — John

Yes, I'm a realist, but first I just want to clarify this: earlier you'd said, "There is no reality apart from what we perceive and think about what we perceive." Now you're using the word "can."

"There is no reality apart from what we perceive and think about what we perceive"

is different than

"There is no reality apart from what we perceive and think about what we CAN perceive."

Also, I'd want to clarify if you're including things we can know indirectly, for example, via scientific instruments, in "what we can perceive."

Was there an earlier discussion in this thread that I didn't read that was specifically about sight? Just curious, because people keep focusing on that.

Anyway, re this, and looking at the dispute in more general terms:

In the most basic line length illusions for example you simply get out a ruler and measure the lines or in the case of false convergence you measure the angles. — Barry Etheridge

Do you believe that you can accurately know what the ruler says?

Do you believe that you can accurately know what the ruler says? — Terrapin Station

Oooh, sneaky! Liking your work!

But actually, probably not if we're being that analytical about it. For pragmatic purposes, however, one has to assume that the brain's distortion of reality is at least consistent to the point that the same degree of modulation is in operation on every line measured by the same ruler.

If you're actually asking the deeper question "Is there any such thing as accurate measurement?" then it's going to be a long night!

I would say that what we perceive and think about it just is what we can perceive and think about.

And of course scientific instrumemts are either direct augmenters of our senses (telescopes, microscopes) and /or things that are believed to be such (spectroscopes, cloudchambers, electron microscopes and so on).

Well, it's just getting back to the point I made earlier: "in order to know that something is an illusion in the first place, you'd need to be able to know what it's really like in contradistinction to what you thought it was like."

You're believing that the ruler tells you what the material creating the illusion is really like. You're assuming that the ruler isn't itself an illusion, etc.

This is a problem with representationalism and like theories in a nutshell: they typically rely on a belief that perception doesn't tell us what the world is really like, because of, for example, scientific knowledge of how our perceptual mechanisms work (and trick us and so on in the case of illusions). But to come to that belief in the first place, we have to believe that we can know what our perceptual mechanisms are really like via scientific research, but if we can know that, then the theory is wrong, because we can know something about what the world is really like independently of our perception after all.

I would say that what we perceive and think about it just is what we can perceive and think about. — John

That I'd agree with, of course, since it's a tautology. But it's a different issue than whether that's all there is, and whether all there is is exhausted by either (a) what we actually do perceive and think about, or (b) (more broadly), what we potentially can perceive and think about, even if we're not currently perceiving and thinking about it.

That I'd agree with, of course, since it's a tautology. — Terrapin Station

But, you were claiming earlier that I had changed what I was saying.

But it's a different issue than whether that's all there is, and whether all there is is exhausted by either (a) what we actually do perceive and think about, or (b) (more broadly), what we potentially can perceive and think about, even if we're not currently perceiving and thinking about it. — Terrapin Station

Of course, since we have come, historically to perceive and think about more and more, then it would seem that what we currently perceive and think about may not be all there is.

This also answers your next point; we may come to perceive and think about more in the future. Alternatively there is also the possibility that in regards to some dimensions of reality we have come historically to perceive and think less, or even not at all.

But, in any case you have not answered my question which challenged you to identify in what sense I am not an ordinary realist, since you asserted that. I asked you, since the implication seemed to be that you are an ordinary realist, what kind of reality could exist that we cannot (now or could not ever come to, just to be clear) perceive and/ or think about.

The first in my last series of posts on this thread was a statement contra Hoffmans so-called 'theory' that reality is nothing like what we perceive it to be. I didn't really want to become embroiled in silly arguments about realism vs anti-realism; I don't think those arguments are of any philosophical importance; they are the archetypal red herrings.

Your conclusion it seems to me holds good only for the most extreme version of representational theories, ie. those which posit that our perceptions are totally unrelated to what's out there. I have never proposed any such thing. Indeed I'm not sure how anyone could realistically hold such a view and not go bonkers!

But, you were claiming earlier that I had changed what I was saying. — John

Yes, and this again is different:

(A) "There is no reality apart from what we perceive and think about what we perceive."
(B) "There is no reality apart from what we perceive and think about what we can perceive."
(C) "What we perceive and think about it just is what we can perceive and think about."

Those are three different claims. I only agree with (C).

But, in any case you have not answered my question which challenged you to identify in what sense I am not an ordinary realist, — John

Sure:

(A) and (B) are basically George Berkeley's position--"esse est percipi." He's an iconic example of an idealist. It's just that one--(A)--would be saying that reality is only what we think/perceive at the moment, whereas the other--(B)--is noting that reality can change with what we might differently think/perceive in the future.

(B) could also be seen as saying that reality consists for some reason ONLY in things that we can at least potentially think perceive, but not that it's identical with what we think/perceive at the moment, but that's not clear from just the statement of (B). That's one reason why I had asked you this: (D) "Also, I'd want to clarify if you're including things we can know indirectly, for example, via scientific instruments, in 'what we can perceive.'" That was the attempted beginning of trying to clear that up.

(C) on the other hand is noncommital about the realism/idealism issue. It merely states a tautology, namely, that we can't think and perceive something that we can't think and perceive. That doesn't tell us anything about, for example, whethere there exist things that we can't think and perceive.

I asked you, since the implication seemed to be that you are an ordinary realist, what kind of reality could exist that we cannot (now or could not ever come to, just to be clear) perceive and/ or think about. — John

Again, to be able to answer this, I need to know your answer to (D) above. Your answer on that will prompt different answers from me to the question you're asking.

Your conclusion it seems to me holds good only for the most extreme version of representational theories, ie. those which posit that our perceptions are totally unrelated to what's out there. I have never proposed any such thing. Indeed I'm not sure how anyone could realistically hold such a view and not go bonkers! — Barry Etheridge

This is why it's relevant to note what I posted earlier: No one has a view that posits that one accurately knows noumena 100% of the time. So any argument based on that idea would be a straw man.

If you're assuming that sometimes we can get external facts right via our perception, then it would turn out that you're making an argument for realism. (Not that that argument is necessary for realism, by the way, but it would be sufficient for it.)

Those are three different claims. I only agree with (C). — Terrapin Station

But that is not the point. I don't care whether you agree with claims A and B. You claimed that they were not the same, i.e. that claim C is not correct and now you say you agree with it. I wanted you to clarify that apparent contradiction in your position.

Again, to be able to answer this, I need to know your answer to (D) above. Your answer on that will prompt different answers from me to the question you're asking. — Terrapin Station

Apparently then, you missed this:

And of course scientific instrumemts are either direct augmenters of our senses (telescopes, microscopes) and /or things that are believed to be such (spectroscopes, cloudchambers, electron microscopes and so on). — John

Now you should be able to answer.

I think there is something objective; that is, the things that we can perceive though our senses. Now, subjectivity enters the mix by trying to interpret what these stimuli mean. That is where our conscious mind takes hold.

These are complicate issues and I recognize my own faults, so I implore you to point faults in my assertions.