How Do You Know that You Know What You Know?
0:00 This video is brought to you by CuriosityStream. Consider the following: let's say you're in school, you're doing your math problems exactly like you're supposed to, and all of a sudden, you look down and you're in your underwear. You're not in any other clothing at all. What would you do? Well, if it were me, I'd freak out because that's a pretty damn crazy situation, and I would hope nothing like that has ever happened.
But it has. Not in reality, of course, but in my dreams. And not just in my dreams, in quite a few people's dreams. The idea of going to school naked or in your underwear is something that a lot of people have experienced. So, this begs the question: if this dream were to happen to you, how would you know that it was a dream and not actually happening? In and of itself, it's not immediately obvious. And to me, it begs the broader question of, well, if you can't tell that that's a dream, how can you tell that this is actually real? This begs the even broader
1:01 question: how do we know if anything is real, not everything? Such a question would seem to impose a sort of simulation hypothesis on us, but that's not what I'm trying to say. How do I know that this hand before me is real? How do I know that this camera I'm looking at—how do I know that anything is anything? I don't know about you, but to me, the answer isn't intuitively obvious. And to be frank, I don't think I have the answer to this question, and here's why.
If we were going to try to find out if any particular thing was real, I think we could make a basic distinction between two separate ways of going about doing that. The first would be using our senses. So, that would be touching, tasting, seeing, smelling, hearing—the five basic senses enumerated by Aristotle. These are nothing new, and it's very obvious how we use them to detect things. You sense something and you think it's there, obviously. But at what point do we say something is
2:01 what we say it is? This sounds like a very convoluted question, and that's because it is. But if I were to make it less convoluted, it's a question of when does a thing stop being what it is? For instance, if I have an orange and I eat it, it's no longer an orange once it's eaten. It's an eaten orange. But is it even an orange anymore, or just the rind? The answer as to what we should call this is, again, not obvious.
So, how can we tell when our senses are designating something versus the decomposer of something else, or the composition of things into other things? Where is the point at which a thing begins to be a thing and not something else? I don't know. I really could not tell you, to be honest with you. I really don't know how we would solve this problem, but I can raise more instantiations of it. For instance, if we were to talk about water and ice, at what point does water become ice? When its molecules are distant enough that it seems to be solid, but at what point is it solid enough to
3:02 be called a solid? This is a problem that's been raised for generations, as a matter of fact, not in the context of water and ice, but rather in the context of glass. Some people contended that it was a solid since it feels solid, but using their sense data from their eyes, other people said, "Well, no, it seems to be more like a very, very, very slow-moving liquid," because over time, ripples could be seen in it. As science now tells us, well, it doesn't seem to be either, but rather something in between the two.
This begs, then, a further question: if we can't trust our senses to designate when a thing is a thing—solid, liquid, gas, or even itself—when should we have recourse to science? When is our knowledge limited enough that we cannot trust it? I don't know, I really don't know.
If I were to consider this problem further, I would then think of the issue of intersubjectivity. That is, when multiple people are experiencing
4:03 subjective sensory experiences, how do we know that they're actually correlated? That is, how do we know they correspond to something objective? It doesn't seem like we can know that, not certainly. At least for me, the best example of this phenomenon is found in the cilantro plant. For some people, it tastes like a plant; it tastes actually pretty terrible, like soap, um, as the common description would go. For other people, it tastes like a spice, and it's relatively common in Mesoamerican and in other Hispanic cuisines. What's the real flavor of cilantro? Nobody really knows. Perhaps that question is illogical, I don't know. But whatever the case may be, it's not something that can be proven objectively because there's too much subjective contingency to be had.
Of course, then you could also point to optical illusions, one of the most philosophically significant being this rabbit-duck illusion. It was first referenced philosophically by Ludwig Wittgenstein,
5:05 and as he pointed out there's an ambiguity to it because it's a depiction and well because it appears differently at different times sometimes a duck sometimes a rabbit to say what it is then doesn't really seem like something that can be divorced from who sees it when they see it and how they see it the subjective context surrounding its being seen so if that can be the case for depictions why can't it be the case for things as they actually are when is an actual rabbit in actual rabbit i suppose you could have recourse to dna and molecules and everything like that but then that's beyond our sense data that goes into assumptions about the nature of how things are again the answer to this question just does not seem obvious no matter what the case it seems that our senses cannot be relied on wholly and totally
6:07 so what about that second division and how we know things two separate ways what about that can we know anything that way that division would be the mind or as aristotle may call it in some particular respect the common sense or nowadays just common sense can we trust our common sense intellectual understandings of things doesn't seem like we necessarily can i mean just looking at it on the face of things consider we're just apes on this rock flying through space so what's the guarantee that there's anything inside of us that is correspondent to what's outside sure you could make an argument from evolution and say well it's likely that we have to have some degree of certain knowledge or else well we'd be dead we couldn't survive but if one wants to talk about broader claims and the certainty of all of our knowledge it doesn't seem like we can make that claim wholly and totally consider the commonsensical
7:08 view of geometry what's typically called euclidean geometry it consists of simple circles squares triangles and like but if we are to take certain interpretations of einstein's theory of relativity as correct that's not how the universe is actually shaped though it would seem to us to be that way especially here on earth it looks like the earth is flat and it looks like space should obey general euclidean laws as einstein's theorem points out however and as we know of the surface of our planet those laws are not universal and they don't seem to hold in space itself for einstein and according to most modern astrophysical theories space has a curvature to it and that's not something simple common sense euclidean geometry can easily account for so doesn't seem like the common sense view of shapes can apply so can anything else to the ancients this entire discussion would fall under the notion of form
8:10 mostly for plato the notion of a form was something out there in the world this kind of transcendent other which gives things an intelligibility to them it is the mind that has the capacity to understand these things and to engage with the super mundane world of the divine forms of course this begs the question where the hell do they come from and plato doesn't really tell you he just says god made him not any god the craftsman god called the demiurge but that's neither here nor there aristotle takes a moderate position on the matter and says that rather these things are just in objects themselves but as we've just said if circles don't really exist in the real world if the world is not to be conformed to euclidean shapes which are just too simple for it and where the hell did the form of a circle come from it seems like we just made it up same goes for all the other shapes too at what point then can we say
9:11 that what we have made up and what we haven't made up are even in the same set of things? Where is what's really there? How do we even know that we have connection to what is really there, at least as concerns these shapes and forms? Again, it doesn't seem to be a way to prove it. [Music] It seems more reasonable that everything we think is simply inside our heads. Perhaps it has some loose correspondence to what's really out there in the world, but it's exactly that—a loose correspondence and not one with any absolute guarantees to truth.
In the Middle Ages, people often thought that rats would appear spontaneously out of hay, as would flies and other things as well. This theory of causality was called spontaneous generation. At the end of the day, it was observable; it was contingent to what people could see. But because there was an error going on
10:12 in people's processes of thinking, well, it wasn't correct. Mice don't really come from hay, though if you looked at hay for long enough, it would seem like they do. It's for this reason that various philosophers in the 1900s came to the conclusion that scientific laws in and of themselves don't really necessarily describe anything legitimate; they're merely conventions, things that just happen to be effective and happen to work.
So, if you ever find yourself in school and you're just in your underwear without any other clothes on, hope to God that it's not really happening, because you don't have a chance in hell in proving that it's actually not happening. However, perhaps we could say that it's just reasonable that it wouldn't be happening, because why the hell would it be? So, with that being said, perhaps we just need to go with what we know best. Maybe we need to have an open mind. Maybe I have no idea what the hell I'm talking
11:12 about the last one is most likely true in the words of socrates i know one thing and that is that i know nothing but you might be wondering why i use dreams to frame this video believe it or not that's not something i came up with rather the problem of dreams is a thought experiment with examples in history and popular media that i couldn't really show on youtube which is why i've put an extended version of this video on nebula with clips that would probably get it to monetize it's for this reason that i and a number of other creators have teamed up to start a platform where we don't really have to worry about demonetization or the dreaded algorithm if you like this video the nebula version removes this and the intro ad entirely and replaces them with additional content of course the sponsor for this video is curiosity stream so why would i bring this up well curiosity stream is an educational platform of its own and in an effort to support independent
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13:15 before I forget, thank you for watching. [Music] Burgers. [Music]
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