Episode 053 - The Senses Are Never Deceived, Even By Illusions
Date: 01/16/21
Link: https://www.epicureanfriends.com/thread/1827-episode-fifty-three-the-senses-are-never-deceived-even-by-illusions/
Summary
Section titled “Summary”Elaine is absent and Charles is under the weather as Martin reads lines 324–468 of Book Four, covering a long series of optical illusions: jaundice causing yellow vision; square towers appearing round at distance; shadows following us; the ship-and-shoreline paradox; the apparent fixity of the stars; children spinning themselves dizzy; the sun rising from the sea as mariners see it; a puddle reflecting the deep sky; an oar appearing bent in water; clouds appearing to race against the moon; and dreams in which we think ourselves awake. The central epistemological payoff is the line: “The eyes are not to be blamed — it is their business to discover only where light and shade are; it is the office of the mind and judgment to distinguish this. For the eyes can know nothing of the nature of things.”
Discussion focuses on what Epicurus actually means by “all sensations are true” — DeWitt’s position that “true” means honestly reported, not true to all the facts. The tower appearing round is connected to Epicurus’s disputed view on the size of the sun. Cassius introduces a point from an EpicureanFriends.com correspondent (Brian) that Epicurus conceives the mind as operating primarily through pictures/images rather than words, which connects to the dreams section and to the Letter to Herodotus on “images attached to words.” A Diogenes Laertius passage is read: “visions of the insane and those in dreams are true, for they cause movement.” The episode closes with a wide-ranging discussion on evaluating expert testimony — how to assess claims from specialists one cannot personally verify — drawn as a direct analogy to Epicurean epistemology, with Cassius noting the parallel to jury-trial expert witness procedure in US courts. Cassius previews a line for next week’s discussion: “If anyone thinks that nothing is known, he knows not whether that can be known either, since he admits that he knows nothing.”
Transcript
Section titled “Transcript”Cassius: Welcome to Episode 53 of Lucretius Today. I’m your host, Cassius, and together with my panelists from the EpicureanFriends.com Forum, we’ll walk you through the six books of Lucretius’ poem and discuss how Epicurean philosophy can apply to you today. Be aware that none of us are professional philosophers and everyone here is a self-taught Epicurean. We encourage you to study Epicurus for yourself, and we suggest the best place to start is the book Epicurus and His Philosophy by Canadian professor Norman DeWitt. For anyone who is not familiar with our podcast, please check back to Episode 1 for a discussion of our goals and our ground rules. If you have any questions about those, please be sure to contact us at EpicureanFriends.com for more information. In today’s podcast, we’ll discuss how mistaken judgments caused by illusions should not be considered to be the fault of the senses, but of the mind. Our text will be from Latin lines 324 through 468. Now let’s join Martin reading today’s text.
Martin: And then, whatever person looks upon that has yellow jaundice becomes pale and lurid, because many lurid seeds flow from such a body and meet with the images of things as they advance. And first, there are many seeds within the eyes of one so distempered which taint all things with the infection and make them look pale.
Again, if you are placed in the dark, you see objects that are in the light because, when the dark air which is nearer first enters and takes possession of the open eyes, the bright clear air immediately follows, which as it were purges the eye and dissipates the darkness the dusky air has infused into it. For this lucid air is by many degrees more apt to move, is more supple, and has more force. This, as soon as it has filled the passages of the eyes with light and opened those pores that the dark air has stopped before, the images of things conveyed in the light immediately follow and strike upon the eye and move the sight. But if we are placed in the light, we cannot discover objects in the dark, because a train of dark and thicker air follows the bright which is nearest the eye, and stops up all the pores, and so chokes up the passages of the sight that the images of things cannot be moved or received into it.
Firstly, when we see the square towers of the city at a distance, they commonly appear round to us, because all angles seen far off show obtuse, or rather they do not show at all. Our strokes die away and the blows never reach our eyes, for as the images are carried through a long track of air, the air beats upon them continually in their passage and so wears off the corners. And it is that since no manner of angle strikes the eye, the stony fabric appears of a circular figure. Yet the roundness is not so distinct as if the object itself were really round and seen at a small distance, but it bears a kind of resemblance to such a figure, yet it is not completely so.
Our shadows seem to move with us in the sun, to follow our steps and imitate our gestures. If you can suppose that air void of light is able to walk and to follow the motion and gestures of the body. For what we usually call shadow can be nothing but the air deprived of light. The reason is because as we walk, we hinder the rays of the sun from striking upon a certain part of the earth, which by that means becomes dark. But as we leave the place, it is covered with light, and therefore it is that the shadow of the body over against it follows us in all our motions. For a train of new rays are continually flowing from the sun, and the first rays fail like thread of wool drawn through a flame. And by this means that part of the earth is soon deprived of light and again becomes bright and discharges the black shade that hung upon it.
But in this case we are not in the least to allow that the eyes are deceived. It is their business to discover only where the light and shade are, but to determine nothing whether the light be the same or the shadow be the same that moves from one place to another, or whether it be as we explained above. It is the office of the mind and judgment to distinguish this, for the eyes can know nothing of the nature of things, and therefore we are not to impute to them the failures of the mind.
When we are on shipboard, the vessel drives on when it seems to stand still, and when it lies at anchor it seems to move. The hills and plains seem to fly and retire from us as we row or scour with full sails before the wind. And thus all the stars seem fixed in the vaulted sky, when they are all in continual motion — they rise and, when they have measured the heavens with their bright orbs, they set again at an immense distance. The sun and moon by the same rule appear fixed, when experience tells us that they move. And mountains standing at a distance from one another in the middle of the sea, so that a fleet of ships may sail easily between them, appear like one continued ridge of rocks; although widely separated, they show like one vast island formed by all of them joined together.
So, boys, when they have made themselves giddy, so strongly fancy that the walls are turned about and the pillars run round, that even when they stand still they can scarce believe the whole house does not threaten to tumble upon their heads. Thus, when Nature begins to display the bright splendor of the sun with a trembling light and to raise it above the top of the mountains, that hill over which the sun just appears and, glowing, seems to scorch with its beams — it is scarce two thousand bow-shots short of distance from us, perhaps not five hundred casts of a dart — when yet between that and the sun lie many mighty seas spread under a vast expanse of the heavens, many thousands of leagues of land between, possessed by many nations and the whole race of wild beasts.
So a puddle of water, no deeper than one of your fingers, that lies in the street between the stones, affords a prospect so deep under the earth as the distance between the earth and the wide arc of heaven, so that you seem to look down upon the clouds, to take a clear survey of the sky, and view with wonder the celestial bodies contained in it as they lie beneath the earth.
Observe when your spirited horse stands still with you in the middle of a river and you look down upon the rapid stream of the water: the force of the current seems to drive your horse violently sideways and hurry you swiftly against the tide, and on whichever side you cast your eyes, all things seem to be borne along and carried against the current in the same manner.
A long portico, though it be of equal breadth from one end to the other and reaches far, supported by pillars of equal height, yet when you stand at one end to take a view of its whole extent, it contracts itself by degrees to a narrow point at the far end. The roof touches the floor and both sides seem to meet, till it terminates at last in the sharp figure of a dark cone.
The sun, to mariners, seems to rise out of the sea, and there again to set and hide his light, for they see nothing but the water and the sky. But therefore you are not to conclude rashly that the senses are at all deceived. To those who know nothing of the sea, a ship in the port seems disabled and to strive against the waves with broken oars; for that part of the oar and of the rudder that is above the water appears straight, but all below, being refracted, seems to be turned upwards and to be bent towards the top of the water, and to float almost upon the surface of it.
So when the wind drives the light clouds along the sky at night, the moon and stars seem to fly against the clouds, and to be driven above them in a course quite opposite to that in which they naturally move. And if you chance to press with your finger under one of your eyes, the effect will be that everything you look upon will appear double. Every bright candle will burn with two flames, and all the furniture of the house will multiply and show double.
Lastly, when sleep has bound our limbs in sweet repose and all the body lies dissolved in rest, we think ourselves awake. Our members move, and in the gloomy darkness of the night we think we see the sun in broad daylight, and though confined in bed we wander over the heavens, the sea, the rivers, the hills, and fancy we are walking through the plains. And sounds we seem to hear, and though the tongue be still we seem to speak, when the deep silence of night reigns all about us.
Many more things of this kind we observe and wonder at, which attempt to overthrow the certainty of our senses — but to no purpose. For things of this sort generally deceive us upon account of the judgment of the mind which we apply to them. And so we conclude we see things which we really do not. But nothing is more difficult than to distinguish things clear and plain from such as are doubtful, to which the mind is ready to add its assent, as it is inclined to believe everything imparted by the senses.
Cassius: Thank you for reading that, Martin. There’s a lot in this material today to talk about, but we have sort of come to the end of the presentation of the evidence — that’s probably the best way to look at it. And that last part you just read: “many things of this kind we observe and wonder at which attempt to overthrow the certainty of the senses, but to no purpose, for things of this sort generally deceive us upon account of the judgment of the mind which we apply to them.” I think that’s really the payoff of much of what we’ve been talking about for the last several episodes. The mistakes we make of judgment are not attributable to the senses themselves, but to what we do with the information from the senses when we process it.
But we’re also missing Elaine today, who’s under the weather. Charles is with us, and so the three of us will tackle what we have here.
Cassius: I almost want to skip past the first of the paragraphs that we read today, because that’s kind of a continuation of the movement of images that we’ve been discussing for one or more weeks. Martin, do you have anything about that first passage and the movement of air between the lights and shadows?
Martin: No, I mean we addressed this basically already. But the one thing which is new — which I think was not included last time — is that if a person is sick, then this may affect the senses. So this is an observation he made in quite some detail, and which is correct, and he tries to incorporate it in his overall explanation. He really tries to come up with a view which can account for every single detail of what we observe with sight.
Cassius: Right. And I think the point that’s important to hit on is to always go back to the issue that people say Epicurus says the senses are infallible, but he doesn’t mean it in the sense that we believe everything we think we see. What he’s constantly teaching in these sections is that illusions of all types can happen. And as you’ve just mentioned, Martin, you can even be sick and your eyes can be malfunctioning, and under those conditions you have to take that into account. A lot of people who take a superficial view of Epicurus and say he claimed “all sensations are true” — these are the passages they need to know about. Once you understand what Epicurus is really talking about, that’s not what he means at all. It’s very easy to ridicule him if you think he said that — but he certainly did not mean it the way it’s taken by his opponents.
Cassius: Now the second of the paragraphs starts with apparently classic illustrations: a tower seen at a distance and why it can appear round even though it is angular. Before I forget, and I don’t want to take this too far because I think we come back to it later — it’s probably worth pointing out that his explanation here, where he says “the strokes die away and the blows never reach our eyes, for as the images are carried through a long tract of air, the air beats upon them and wears off their corners” — I believe commentators have taken the position that this is related to his explanation for why Epicurus reportedly held that the sun is not as large as the mathematicians alleged. Apparently the mathematicians were, as it turns out, accurately computing that the sun was huge. But my understanding is that Epicurus took the position that here on earth, when we see something at a distance, it doesn’t look sharp because the corners are worn away — and that’s not the way the sun looks, because at times we can look up at the sun and the edges, under certain conditions, can be very distinct. So I think that was one of the arguments he incorporated into his explanation of the size of the sun. A couple of things going on there. But those things we’re talking about play into it.
He knew that there are illusions and difficulties in observing sight. And he said that we can’t let those difficulties undercut our confidence in our senses, because ultimately our senses are all we have. So instead of throwing up our hands in despair, what we need to do is study the conditions under which the senses operate well and those under which they don’t, and take that information into account in processing what we receive from the senses.
Any comment on that second passage, anybody?
Martin: No.
Cassius: Okay. And then the third of the paragraphs is another extremely important payoff passage: “we are not in the least to allow that the eyes are deceived. It is their business to discover only where the light and shade are, but to determine nothing whether the light be the same or the shadow be the same that moves from one place to the other. It is the office of the mind and judgment to distinguish this. For the eyes can know nothing of the nature of things.” That line is starting to strike me as very memorable — “the eyes can know nothing of the nature of things.” The eyes don’t know anything. It’s the mind where knowledge takes place, not the eyes or the ears or the sense of touch. So we don’t blame them for the errors in conclusions that we make.
As DeWitt says, the word “true” in the context of “all sensations are true” would mean “honestly reported” — not “true to all the facts necessarily.” Martin, do you pretty much agree with that?
Martin: It sounded okay to me.
Charles: Yeah. At first I thought the “eye can’t know” line from the previous sections was a bit of a cop-out — a very convenient explanation. But when I went back to reread the text I understood why.
Cassius: Yeah. I doubt it would be easy to overemphasize the importance of this material, because this is really the foundation of replying back against the radical skeptics and those who say that everything’s in flux and it’s impossible to know anything. If they’re right, we’re really in a fix. And of course we don’t think the gods or ideal forms are going to help us learn the truth about things — so we have to have confidence in some kind of a method of learning about the world around us, and the senses are that method.
What we have to focus on is: if we end up with a mistaken judgment about something, we have to backtrack our reasoning process and question our reasoning. But in most cases we’re going to accept the evidence — we’re just going to have to look for a new way of interpreting it as new evidence comes to us. Maybe the first of the points Epicurus is making here is that when we find our existing conclusions contradicted by new evidence, we don’t give up confidence in the senses — we go back and backtrack our reasoning to determine where the reasoning was incorrect.
Cassius: One more thing I would point out — the interesting rule of processing we’ve just stated: that we’re going to understand that the senses are honest and it’s the reasoning process that is where the error enters. That’s a conclusion, a philosophical position — and it’s also something we observe to be true. So there’s an interplay between a philosophical position and observations that lead us to our conclusions. Charles, anything you want to comment?
Charles: Not particularly. I know I’m not feeling well today, so I’ll try to shoulder as much as I can.
Cassius: I suppose if I move to the next passage, I’m just carrying on with the same argument, because the next passage starts off with “but in this case we are not in the least to allow that the eyes are deceived” and then goes into the examples of standing on a ship and feeling like the ship is standing still while the coastline moves; stars looking fixed though they’re in continual motion; the sun and moon appearing fixed; mountains looking like a continuous line at a distance; and then the more funny example of children who spin themselves around to make themselves dizzy. The Bailey translation confirms: “when children have ceased turning around themselves, so strongly does it come to appear to them that the halls are turning about and the pillars racing around.”
Cassius: And my mind reading through the remaining paragraphs: the portico example, the sun seeming to rise out of the sea — maybe one point we really need to emphasize about all this is that he’s pointing out something that appears to be an illusion, and then pointing out that we correct that mistaken judgment through additional further observation. We see the sun rise, or we walk down the arcade and see how the pillars are not really touching the floor, or we lift the oar out of the ocean and realize it’s not bent. We correct our mistaken judgments through observation. We don’t correct them by some abstraction we’ve come up with from some other source that we just accept. The thing that we use to prove a mistake and to correct it is observation by the senses.
Charles: I’m curious about the little section on dreams at the end.
Cassius: Yeah, let’s talk about that because it’s a little bit different than the rest. “Lastly, when sleep has bound our limbs in sweet repose and all the body lies dissolved in rest, we think ourselves awake, our members move, and in the gloomy darkness of the night we think we see the sun in broad daylight, and though confined in bed we wander over the heavens, the sea, the rivers, the hills, and fancy we are walking through the plains.”
That’s interesting to throw in here because the others are observations while we are awake, but these are observations we think we are making when we are asleep. Why would he throw that in here? Is having a nightmare going to cause you to doubt the accuracy of your senses when you wake up in the middle of the night after a dream? Certainly not, but maybe he thinks it’s relevant to include here.
Charles: Well, from Diogenes Laertius: “the visions of the insane and those in dreams are true, for they cause movement, and that which does not exist cannot cause movement.” And I think that’s pretty important with all of our talk right now about the sensations. Obviously Diogenes isn’t saying the shadow person we see in the corner of a dream is physically real, but it’s real enough to cause stimulation.
Cassius: Charles, I’m going to go on a tangent for just a second. I had a very good telephone conversation last night with an old friend I met some years ago on the internet, discussing Epicurus — by the name of Brian. He tells me he listens to the podcast and I appreciate that very much. And when I talked to him last night, he gave me a lot of good input. One point he made is that there’s clearly a thread of Epicurean thought that images — in the sense of pictures — are what Epicurus is focusing on as the way the mind operates. More so than the mind formulating what it sees into words, it really probably formulates what we see into pictures. And what we’re storing may well be pictures as much as words.
That’s a deep subject I don’t want to go too far into, but the bottom line is that Epicurus was clearly considering pictures to be part of how the mind operates. So maybe in that sense, a picture that your mind considers while you’re asleep is analogous to pictures your mind sees while you’re awake. It really is the processing of pictures that he’s interested in. So the distortions in the pictures that come to our mind when we’re asleep could seem to Epicurus to be related to distortions or illusions that come to us while we’re awake — since he’s focusing so much on manipulation of pictures as the way the mind operates.
Cassius: With that in mind, there’s an interesting section from Diogenes as well: “for he says all sensation is irrational and does not admit of memory, and is not set in motion by itself; nor when it is set in motion by something else can it add to or take from anything.”
Charles: Yes. The exact thoughts you’re talking about will be covered next week in the very next section of Lucretius. I can only assume that “does not admit memory” is referring back to what Lucretius said: “the eyes can know nothing of the nature of things.”
Cassius: That’s a good question, Charles. I’m certainly not capable of digesting this quickly, but it seems to me you’ve got to dive into whether Epicurus is talking about memory here. He obviously knows that memory exists somewhere — he’s saying the sensations don’t have memory. So clearly the brain has memory. And then the question is: what is memory within the brain? Is it words? Is it pictures? Some combination? Something else? So that when you think about something you remember from the past, are you examining in your mind a series of pictures? I certainly don’t know the answer myself, but it sounds like Epicurus is thinking in terms of pictures.
That reminds me of the opening of the Letter to Herodotus. Doesn’t he say something there about images attached to words? That’s really interesting to consider — what that means, and the issue of whether a word has any content in it at all other than the pictures or images it’s attached to. Is a word anything more than the tag that goes along with an image? Like a computer filing system where you give a number or identification tag to certain content — but it’s really the content that’s important, not the tag.
Cassius: And also this is something Brian reminded me of last night — about Epicurus talking about “casting the mind.” What does that mean and how do you interpret that? I know there’s a lot of commentary. It comes up in the beginning of Book One, where Epicurus casts his mind throughout the universe. That’s probably beyond our ability to talk about today, but I believe that’s some of the Greek involved in the discussion of prolepsis and anticipations, and what the mind is doing when it goes through those processes.
Charles: Epicurus addressed to Herodotus talks about images attached to words. That’s really interesting — the issue of whether the word is anything more than the tag that goes along with the image.
Cassius: This episode is going to be a lot of questions and not very many answers. But ultimately the point becomes: the sensations are all we have as our contact with the universe. So if we ever get the idea that the sensations are just totally unreliable and we should forget them, we’re lost. And specifically, that’s the issue with saying “the eyes know nothing of the nature of things” — the eyes don’t know anything, it’s the mind where knowledge takes place. So we don’t blame them for the errors in conclusions that we make. Even when we’re sick, we should realize that the unclear vision we’re experiencing is a result of the sickness and not because eyes are inherently unreliable.
I don’t think this congested throat is giving me any delirium or images.
Charles: That’s an example — I mean, your throat doesn’t receive information, but your nose, if it’s totally congested, is not accurately smelling the coffee you’re drinking. And yet that doesn’t mean the coffee has no smell. It means you’ve got a condition in your nose that prevents it from being smelled. So if you make the judgment that coffee has no smell because you can’t smell it right now, that’s certainly not the nose’s fault.
Cassius: Where did Martin go?
Martin: The problem is, clearly, I don’t have anything to say.
Cassius: Well, I don’t know that we’re ready to close or not, but in addition to just what we’ve been talking about, one of the issues revolving around all this is how we can make new observations — and new observations are going to be constantly part of life — not all of which are going to be consistent with the conclusions we’ve reached from prior observations. So we have to come up with some kind of processing theory by which we look at our conclusions and decide which ones we should accept as firm and which ones are subject to revision, and how to know the difference between those two.
Martin, do you have any general rule of thumb as to how you separate what you think is confirmed enough that you need not worry about it being revised, versus those things that you’re sure will need revision at some point based on new evidence?
Martin: I think at one point in the past week we were discussing something like the 0.15% or something like that that scientists use to decide whether something is certain. That’s not exactly what we’re talking about, but it’s not entirely different either. It’s a matter of how do you keep in mind that there is a distinction between those things you should be confident about and those you can’t be confident about. Normally, by intuition alone, we can get an idea that something looks reliable. And if we have some doubt, we can think through it — is this an actual deception, or is it a law in science which now produces an exceptional phenomenon? What are the explanations for that? And wherever possible, we try to get more evidence by looking from another angle, touching it, or something like that.
Cassius: Yeah. So if I were trying to list the factors: number of repetitions, I suppose, would be one. If you’re seeing something a thousand times you probably have more confidence in what you’ve observed than if you’ve only seen it twice. And then you’d have to account for the conditions under which those observations took place — ranking the reliability in terms of whether there were any distortions or outside influences that might have made the results flawed.
But then you reach those situations where you’ve had no experience with something, but somebody comes to you and says: I know you’ve never studied molecular biology, but I have, and you should accept my conclusions about the treatment of COVID-19. What’s the right way to consider something you personally have never had any experience in but need to take a position on?
Martin: We certainly need to make sure the person who claims to be an expert is not just an imposter, but really is a scientist who has made those experiments and observations — and also that he is not a maverick but one who is pretty much in the mainstream, so that the information is the best we can currently consider as knowledge.
Cassius: You know, I guess I’m subconsciously channeling my other life as a lawyer into this discussion, because this is exactly what courts deal with in expert testimony in jury trials. I gather that in Germany you don’t use the same jury system we use in the United States, but over here that’s a big part of any trial involving medicine or science. Both sides will submit expert testimony. I think the process is generally describable as: the judge will allow both sides to ask questions of the expert, and before he gives his opinions he has to explain his background, qualifications, and what he’s basing his opinions on — before he even gets the right to give any opinions. And interestingly enough, the judge ultimately makes the decision as to whether he has established himself as an expert using those factors. And the other side will ask him questions about whether he is in the mainstream and how many people agree or disagree with him. That’s the way you’d decide in the United States whether expert testimony comes into the trial.
But there’s one more thing I’d throw in — at least in the United States system of justice, the jury is not required to believe an expert. The jury can dismiss everything the expert says if they find him lacking in credibility. So that’s another factor that probably applies to our philosophical discussions about experts as well.
Charles: People say you’d be a good prosecutor.
Cassius: Well, you know, people run into this all the time. You go to a doctor, get a serious diagnosis, or you think you’re sick and he doesn’t give you one — so you go for a second opinion. And any patient has to decide at what point the evidence and the conclusions the doctors have told him are valid, because you often hear people get a second opinion and get a totally different one.
Martin: In the event of someone claiming expertise in something — if they are mainstream and not rogue, generally a second opinion would agree with them, just as many observations confirm something. But the nature of trials and medical malpractice is that you are often able to get experts on both sides of almost any question. And it’s always interesting to find out how much those experts are being paid and what their motivations might be. So there are a lot of complicated factors to consider. Ultimately, I guess we are responsible for our own lives. Nobody’s going to force us to do anything in most cases. We have to listen to the evidence from all the different sources and ultimately decide how to live our lives based on that evidence. So we’re sort of performing the role of judge and jury in determining which experts we should listen to and which we should not.
Cassius: Okay, we probably have gone long enough for today. Any last comments?
Charles: Are we like halfway through Book Four?
Cassius: I think almost more than halfway through. We’ve got up to Latin line 468 today, and Book Four is like 1,200 to 1,300 lines — so we’re maybe not quite halfway yet. Before we get to the end of Book Four we have to go through the love and sex discussion. Hopefully Elaine will be back with us next week.
Martin, anything further for today?
Martin: No.
Cassius: Okay. One thing that catches my eye before we finish — one of the parts we’re going to run into next week that’s related to what we’re talking about today is a line that always stuck with me from Book Four. Bailey translates it as: “If anyone thinks that nothing is known, he knows not whether that can be known either, since he admits that he knows nothing.” That’s one of the payoff conclusions of this whole discussion. And I remember when I first came across that line and read DeWitt’s analysis, DeWitt points out that the argument is sort of purely logical — a very high-level refutation that turns on the definitions of the words “knowing” and “nothing.” It just continues to strike me how we have an interplay of focusing on the evidence of the senses, but at the same time employing logical arguments to bolster the same conclusion. So we’ll discuss that in detail next week.
Okay, well Charles I hope you feel better, and I hope Elaine will be back with us next week. And Martin, as always looking forward to you too. With that we’ll close for the day.
Charles: Thanks, bye.
Martin: Okay, bye.