 So we're going to take a look at this premise and now I've got to use notes because this gets complicated So we have this premise all knowledge is based on perception reception various from person to person and People disagree on reality. All right. If this is a one-long conjunction So if we're going to reject this premise what happens is we have returned each part of the conjunction right conjunction is where you have an and in between so I Am sitting on a rock and the birds are singing. That's a conjunction if we reject a conjunction We have to negate each part of the conjunction and turn it into a disjunction a disjunction isn't either or So if we say it's false that I'm sitting on a rock and there are birds singing they would say well either I am not sitting on a rock or they're not birds singing or we have this conjunction I am sitting on a rock and There's a hippopotamus behind me. Well, that statement's false Since we reject that statement we say either I am not sitting on a rock or there is not a hippopotamus behind me Okay, so that's what happens when you reject a conjunction So we have the conjunction all knowledges based on perception perception various in person to person and People disagree on reality if we reject this We say either Not all knowledges based on perception or Perception does not vary from person to person or people agree on reality Well, let's try the the last part first and we're going backwards. Do people agree on reality? No No, we get to look at the first set of philosophers that we study so far and figure out that people don't agree on reality It won't take a lot before you find somebody with with whom you disagree about reality Yeah, people very much disagree about reality Okay, perception does not vary from person to person Well, no perception does vary from person to person You know each person's perspective is unique, right? Even if I had somebody sitting right next to me or there still be some difference in the perspective Right with the perceptions if I had one can have the camera here if I had another one over there And I were to flip between the two You what I wouldn't just have the same image, right? You have this kind of jagged image and I would do it But I'm not going to because that takes too long And I don't have a second camera You know not to mention the fact that yeah, even just within oneself there are variations How you perceive things changes over time you lose hearing your sight in Lose taste right we can go one here. So you disagree with yourself over time People disagree, you know, there are differences in how people perceive right? I am slightly colored deficient meaning I see colors just not as many as you do so you and I can both look at the same object And I might see a different color than you so yeah, there is You know people there is very you know perception does vary from person to person so we can't do that Well, then what about this? Not all knowledges based on perception Wow, okay, so there's some knowledge this is just you know with this Suggestion here. There's some knowledge That's not based on perception Huh? So I know something without perceiving it. Hmm. I wonder what that could be That's can you think of an example of some kind of knowledge that you know Without perception Let's return let's let's put a Thumbtack in that one. Let's come back to that idea maybe at the end of the video All right, let's go on to the next premise So the next premise if on if all knowledges based on perception perception various in person to person and people disagree Then there's no test to determine who's right. So this is a conjunction And if we reject a conjunction We have to accept the conjunction with the negation of the second part. So here we go if I'm sitting on a rock Then I'm sitting on a soft surface That conditional is false Right that conditional is false. So since it's also I am sitting on a rock and I am not sitting on a soft surface So that's how you reject a conditional. So for this one, we say all knowledges based on perception Perception various in person to person people disagree and there is a test to determine who is right Okay, wow Hmm, what would this What would this look like? Okay, so Let's try that. Let's say, okay So maybe we just for the moment accept that all knowledges based on perception, right? All right, so this is a conjunction which means we have to accept all the parts of it So let's start all knowledges based on perception. Okay, so we mean maybe that's well, but let's just accept it for the time being Perception various in person a person, okay So right right so far so good all knowledges based on perception perception various in person person people disagree So far all this looks right the first three parts of this look right and then we have this lesson There's a test to determine who's right Well, what would the test be? right if there's a test to determine who's right and All knowledges based on perception then the test has to be perception well if that's true You know will people disagree and your knowledge very sorry perception very some person a person So if there's a test to determine who's right is based on perception even though everybody disagrees and That's all that we have is a disagreement right since it's based on perception. It's all we have is a disagreement So this all in all right this entire conjunction probably is a contradiction If there's a test to determine who's right it can't be based upon The perception because perceptions all we have and that's where our knowledge come from when we all disagree So this this premise is probably I mean I said this a contradictory. It's probably a It's probably a contradiction. We can't accept this contradictory if we can't accept the contradictory We can't reject this premise Okay Let's try the next one If so the next premise is if there's a test to determine who's right Then there's no way to distinguish between Appearance and reality so if we reject this premise we say there is no test to determine who is right There's no test that determines right and there is a way to distinguish between appearance and reality Would the way to distinguish between appearance and reality be the test so this contradictory also results in a contradiction Which means we can't accept this contradictory and if we can't accept this contradictory. We can't reject the premise So, we can't reject this premise either. So far, there's three premises and only one stands any chance of being rejected and it has a weird conclusion, some non-empirical knowledge. All right, third premise. If there's no way to distinguish between appearance and reality, then there's no way to know absolute truth. And if we reject this premise, what we're committed to is there is no way to distinguish between appearance and reality. And there is a way to know absolute truth. Wouldn't the way to know absolute truth be the way to distinguish between appearance and reality? So this looks like another contradiction. So this contradictory has a contradiction, which means we can't accept the contradictory. And if we can't accept the contradictory, we can't reject the premise. So this is four premises now, three of them we can't reject, because rejecting them results in contradictions. All right, let's try the last one. If there's no way to know absolute truth, then everyone is right. Okay, well, if we reject this premise, we say there is no way to know absolute truth and not everyone is right. There's no way to know absolute truth and not everyone is right. Okay, well, hold on a second. The last part of that statement, not everyone is right, that's not a relative truth, is it? A relative truth would be to say something like, not everyone is right upon some condition, right? Not everyone is right during the daytime, right? That'd be a relative truth. Not everyone is right, depending on what you believe, right? That would be a relative truth. As a state, it's just not everyone is right regardless of anything else. Well, if not everyone is right regardless of anything else, that's an absolute truth. And if it's an absolute truth, the first part is that there is no way to know absolute truth. So I don't, not everyone is right, that's not an absolute truth, but I don't know it. It's not exactly logical contradiction, but it's strange. I wouldn't want to accept that premise. Not everyone is right. Are you sure? Yes, I'm sure. Not everyone is right. Do you know this? No, I don't because there's no way to know absolute truth. So these are protagonist's premises. And I, you know, so far they're a little, you know, so far we haven't, we can't reject three of them. The first one, if we try to reject it, it results in something where we have this non perceptual knowledge we have to talk about. And this last one, we say, well, there's, there's absolute truth, but I don't know it. By the way, all the mathematics, we tend to think of mathematics as absolute, so we don't know any math anymore with that last one. So rejecting protagonist's conclusion comes with some difficulties. Either we don't know any absolute truths, maybe we'll just guess at them, or we appeal to some kind of non perceptual knowledge. That's hard. Well, let's move on to Gorgias's premises. See if we can figure out a premise to reject. Protagoras is hard. Maybe rejecting Gorgias will give us a way out. Okay, so the first premise we're looking at. If something exists, then we use perception to know the thing. If we reject this premise, we're committed to its contradictory, which is something exists and we do not use perception to know the thing. Huh. Well, we got some non perceptual knowledge again. We saw this earlier with Protagoras. Gorgias seems to pop up again. I asked you to think of an example. Of something you know without using perception. Have you thought of one yet? All right, let's move on to the next premise. If we use perception to know the thing, then our perceptions are not the thing. So looking around, right? I perceive green and brown to know that there's a tree there. Now the tree is wood, water, cellulose, vitamins, minerals, things like that, right? That's not the same thing as green and brown. Green and brown are caused by the wood, the cellulose, the vitamins, minerals, all that, but it's not identical to that. So if we were to reject this premise, we say we use perceptions to know the thing and our perceptions are the thing. So if we say this and we say, well, that tree over there, it's not wood and cellulose and water and vitamins and minerals. What it is is green and brown. That's kind of strange. Believe it or not, we're going to see a philosopher who says this with a serious straight face. It's like, yeah, you think that's wood, it's not wood. That's just cellulose. There's no wood over there. What's over there is green and brown. It's called metaphysical idealism. Probably not going to, or I just thought it was just called idealism. Probably not going to accept that one. So let's just leave that aside for now. Maybe we have to come back to it, but we'll just leave that aside for now. Okay. So far, we get rejected one premise, gives us non-perception knowledge. Rejected the second premise, we have idealism, which is weird. Next premise. If our perceptions are not the thing, then we know our perceptions, but not the thing. So if we reject this premise, what we're saying is our perceptions are not the thing. All right. And either we did not know our perceptions or we know the thing. Now, the reason why we had this premise to begin with is, or what Gorgias is getting at here is to say that we know our perceptions, right? I have my perceptions green and brown. But since that's what I know, I don't know wood, cellulose, fiber, minerals. That's what I don't know that all I know is green and brown. So if we reject this premise, we say our perceptions are not the thing, and either we do not know our perceptions or we know the thing. Well, we probably don't want to say that our perceptions, we don't want to get rid of it. Our perceptions are not the thing. Yeah, that seems right, right? That's wood, metal, or sorry, that's cellulose, water, oil, vitamins and minerals, right? When I walk away, my perceptions, that thing go away. I don't have the perceptions. But the thing remains. So we don't want to say our perceptions are, we don't want to say our perceptions are the thing, right? So, okay, so to keep that, our perceptions are not the thing. And now we have a disjunction. Either we do not know our perceptions or we know the thing, right? Well, let's just grant that we know the thing. Okay, now we're going to say we don't know our perceptions. I mean, I don't think anybody wants to give up the idea that we know that there's a tree. Okay, so we have to give up, we do not know our perceptions? Well, here's the thing though. So what we can do is we can say our perceptions are not the thing, fine. And yet we know the thing. All right, if our perceptions are not the thing and yet we know it, what we know is non perceptual, which is weird. So we can reject this premise and that's fine. But the only way that we can reject this premise and accept the contradictory is if we say there's some kind of non perceptual knowledge. Accounting for that is going to be hard. So the next premise. If we know our perceptions but not the thing, then the thing is incomprehensible. So if we reject this, right, we're committed to, we know our perceptions, but we don't know the thing and yet it's comprehensible. This is probably a contradiction. I know it, but it's not comprehensible. So wait, what? So no, that, or sorry, I don't know this thing. I don't know this thing, but it's in and yet it's still comprehensible. How can you know it? I can't. There's no way, but it's comprehensible. All right, that's not going to work, right? That's not going to work. That's probably a contradiction. Okay, next premise. If something is comprehensible, then a person uses symbols to talk about it. So symbols, right, so if I understand trees, what do I use? I use words to talk about trees. Maybe I draw something to talk about trees, right? It's not the same thing as a thing symbolized. These are symbols. Okay, pretty standard stuff. If we reject this premise, what we're saying is something is comprehensible and a person does not use symbols to talk about it. I understand something. What is it? Can't tell you, but I understand it. Will you tell me anything about it? Not really. I can't use symbols. I can't use words to talk about it. I mean, if you can think of something, I'd like to see an example. That's probably going to be impossible since any example is going to use symbols to talk about it. But if you can think of something, I'd be kind of curious to see what you'd come up with. But this isn't necessarily a logical contradiction, but I don't know what it would be. I've got secret knowledge that I can't talk to you about. I don't know if you've got secret knowledge then, buddy. All right, next premise. If a person uses symbols to talk about it, then the symbols are not the same thing as the things symbolized and symbols understood only by the speaker. So what Gordjajas is trying to get at here is that, I use symbols to talk about trees. I use words to talk about trees. The words are not the same thing as the things symbolized. I can say wood, cellulose, water, oil, but I am not there by making wood, cellulose, water, and oil. I'm not speaking these things into existence. So it's not the same thing as the things symbolized. And the symbols are understood only by the speaker. What Gordjajas is getting at here is, only I know what I mean when I talk about wood, cellulose, water, and oil. You don't have access to my mind, right? Especially since we're not even in the same room together right now. We're not even in the same place, same time. By the time you watch this, I will have left this place. So there's no way that I could just directly transmit what's in my mind, even if you were sitting right next to me, I couldn't directly transmit what's in my mind. So only I know what I mean when I talk about trees. So if we're going to check this premise, what we're saying is a person uses symbols to talk about it. I use words to talk about trees. Either the symbols are the same thing as the things symbolized. So I say tree and it comes into existence. Or the symbols are not understood only by the speaker. Okay. Well, we're probably not going to say the symbols are the same thing as things symbolized. And let's just start talking about creation by verbalization. We're going to do that. So we're left with a person uses symbols to talk about it. And yet symbols are not understood only by the speaker. More than one person understands the symbols. Well, how's that going to happen? We don't really have a logical contradiction, but the question is how is it going to happen? Any way that we convey symbols is going to be through some kind of sensory input. If I'm going to speak to you using words, you have to be able to hear them. If I'm going to write out words on a screen, you've got to be able to see the words. So you're always going to use perception. So the meaning of those words or those symbols is not going to be in the perception. So if there's understood by more than one person, probably going to have to appeal to some kind of non perceptual knowledge. And even weirder non perceptual knowledge that we all have access to. All right. Next premise. If symbols are not the same thing as the thing symbolized and symbols understood only by the speaker, then no one else understands what a person is talking about. Okay. Well, if we reject this proposition, this premise, what we're saying is symbols are not the same thing as the thing symbolized and symbols understood only by the speaker. And it's false that no one else understands what a person is talking about. So we say, okay, so symbols are not the same thing as the thing symbolized. And only I know what I mean by my symbols. Yet you understand me. How would that work? I am, so if this contradictory is right, then I am speaking right now, but nobody knows what I'm talking about. I'm just speaking gibberish. And yet you understand. No, right? This is probably a contradiction. This is probably a contradiction. And if this is a contradiction, we can't accept this contradictory. Thus, we can't reject the premise. So we have to keep this premise. If these symbols understood only by the individual, then we can't communicate. Okay, so the next premise. If no one else understands what a person is talking about, then communication is impossible. If we reject this premise, we are committed to no one else understands what a person is talking about and communication is possible. Well, let me show you how that will work. Got it? Now, unless we somehow learn telepathy, this is just false. It's not a contradiction. It's just false, right? It's just false. We have to use symbols in order to communicate with each other. And we have to understand what these symbols mean, independent of perception. Well, all right. So so far, it looks like the main way that we're going to get out of both protagonists and gorgias is some appeal to nonperceptual knowledge. And I asked you to think of an example. It's something that you know without the use of perception. It's not justified by the perception. It's not the same thing as the perception, right? Okay. Did you think of an example? Well, okay. Pause the video and try to think of an example. I'll wait. Okay. So trying to think of an example of nonperceptual knowledge, numbers. You don't perceive numbers. You might perceive a numeral, but that's not the same thing as a number. You might perceive two things next to each other, but that's not the same thing as the number two. The number two, it does not come and go with your perceptions. You perceive numerals and they go away. You perceive pairs of things and they go away. But the number two is still something that is true and exists. Two plus two equals four, right? This is true independent of perception. And if you don't believe me, it's like, well, I've seen two pairs of things and then I got four. Okay. But I can start thinking of numbers that are arbitrarily large. You can be able to add them together and you will not have used perception because you can't perceive that many things at once, right? So 65,482 plus 4,608. Well, I'm not going to try and add that up at the top of my head because I just thought of those two numbers right now. But you can add those, right? You can add those together and you will be able to come up with something that's true. But it doesn't rely upon perception because you can't, I mean, maybe you could sort of perceive that many things at once, but you don't perceive them as a multitude of things. If you don't believe me, how many leaves are behind me? You don't know. Okay. There's not that many leaves. How many twigs are behind me? Right. You don't know just by perception to sit there and count it, right? You have to pause the screen and count. And yet you've been staring at it this whole time. You know, how many hairs do I have in my head? You can't perceive number. So yeah, this is an example of something that you know without perception. Even people who do not have sight, they can understand mathematics, do not have hearing. They can understand mathematics, right? In theory, I suppose, you can understand these without very much, if any, perception at all. There's other kinds of form too. Sure. The scientific method. That's form, right? The scientific method is not the thing that's perceived. It uses perceptions. Okay, we have to use perceptions in order to use the scientific method, but the scientific method is not the same thing as the thing perceived. If you think it is, what color is the scientific method? So this non-perceptual knowledge, you already think they're examples. And that's going to be our way to escape protagonists and grudges. But non-perceptual knowledge is strange. How do we know, right? How do we know what we think we know absent perceptions? It's not hard to say, there's a tree behind me. How do I know? Because I see it. If I say something like, there's a tree behind me. How do I know? Not through sight. That would be weird. But still, where protagonists and grudges have given us these conclusions that we cannot accept. We can't accept these conclusions and be rational. We have to reject them. But it sure seems like the main way, if not the only way, that we can reasonably reject these conclusions is to appeal to some kind of non-perceptual knowledge. This is going to send us running and screaming to Plato and Aristotle. We're going to try and give us some account of non-perceptual knowledge.