字幕表 動画を再生する 英語字幕をプリント Hey, Vsauce, Michael here. This appears blue, this appears yellow, and this appears green. Those of us with normal color vision can probably agree. But, that doesn't change the fact that color is an illusion. Color, as we know it, does not exist in the outside world, beyond us, like gravity, or protons do. Instead, color is created inside our heads. Our brains convert a certain range of the electromagnetic spectrum into color. I can measure the wavelength of radiation, but, I can't measure, or observe, the experience of a color inside your mind. So, how do I know that when you and me look at a strawberry, and, in my brain, this perception occurs, which I call "red," that, in your brain, a perception like this doesn't occur, which you have, of course, also learned to call red. We both call it red. We communicate effectively and walk away never knowing just how different each of our internal experiences really were. Of course, we already know that not everybody sees color in exactly the same way. One example would be color blindness. But, we can diagnose and discuss these differences because people with the conditions fail to see things that most of us can. Conceivably, though, there could be ways of seeing that we use that cause colors to look differently in different people's minds, without altering their performances on any tests we could come up with. Of course, if that were the case, wouldn't some people think other colors look better than others? Or, that some colors were more complimentary of others? Well, yeah, but doesn't that already happen? This matters because it shows how fundamentally, in terms of our perceptions, we are all alone in our minds. Let's say I met an alien from a far away solar system who, lucky enough, could speak english, but had never, and could never, feel pain. I could explain to the alien that pain is sent through A-delta and C fibers to the spinal chord. The alien could learn every single cell, and pathway, and process, and chemical involved in the feeling of pain. The alien could pass a biology exam about pain, and believe that pain, to us, generally is a bad thing. But, no matter how much he learned, the alien would never actually feel pain. Philosophers call these ineffable, raw feelings "Qualia." And our inability to connect physical phenomenon to these raw feelings, our inability to explain and share our own internal qualia is known as the "Explanatory Gap." This gap is confronted when describing color to someone who's been blind their entire life. Tommy Edison has never been able to see. He has a YouTube channel where he describes what being blind is like. It's an amazing channel. In one video he talks about colors, and how strange, and foreign of a concept it seems to him. Sighted people try to explain, for instance, that red is "hot," and blue is "cold." But, to someone who has never seen a single color, that just seems weird. And, as he explains, it has never caused him to finally see a color. Some philosophers, like Daniel Dennett, argue that qualia may be private and ineffable simply because of a failure of our own language, not because they are, necessarily, always going to be impossible to share. There may be an alien race that communicates in a language that causes colors to appear in your brain without your retina having to be involved at all. Or, without you having to have ever needed actually to see the color yourself. Perhaps, even in English, he says, given millions and billions of words used in just the right way, it may be possible to adequately describe a color such that a blind person could see it for the first time. Or, you could figure out that, once-and-for-all, yes, or, no, in fact, you and your friend do not see the same red. But, for now, it remains the case that we have no way of knowing if my red is the same as your red. Maybe one day our language will allow us to share and find out, or, maybe, it never will. I know it's frustrating to not have an answer, but, the mere fact that you guys can ask me about my internal experiences, and the mere fact that I can ask my friends and we can all collectively wonder about the concept of qualia is quite incredible, and also quite human. Animals can do all sorts of clever things that we do. They can use tools, problem solve, communicate, cooperate, exhibit curiosity, plan for the future, and, although we can't know for sure, many animals certainly act as if they feel emotions- loneliness, fear, joy. Apes have even been taught to use language to talk to us humans. It's a sort of sign language that they've used to do everything from answer questions, to express emotion, or even produce novel thoughts. Unlike any other animal, these apes are able to understand language and form responses at about the level of a 2.5 year old human child. But, there is something that no signing-ape has ever done. No ape has ever asked a question. Joseph Jordania's "Who Asked the First Question?" is a great read on this topic, and it's available for free online. For as long as we've been able to use sign language to communicate with apes, they have never wondered, out loud, about anything that we might know that they don't. Of course, this does not mean that apes, and plenty of other animals, aren't curious. They obviously are. But, what is suggests is that they lack a "Theory of Mind": An understanding that other people have separate minds. That they have knowledge, access to information that you might not have. Even us humans aren't born with a "theory of mind," and there's a famous experiment to test when a human child first develops a "theory of mind." It is called the "Sally-Anne" test. During the test, researchers tell children a story about Sally and Anne. Sally and Anne have a box, and a basket, in their room. They also happen to have a delicious cookie. Now, Sally takes the cookie and puts it inside the box, and then Sally leaves the room. While Sally is gone, Anne comes over to the box, takes the cookie out, and puts the cookie inside the basket. Now, when Sally comes back, the researchers ask the children "where will Sally look for the cookie?" Obviously, Sally will look in the box- that's where she left it. She has no way of knowing what Anne did while she was gone. But, until the age of about 4, children will insist that Sally will check the basket because, after all, that's where the cookie is. The child saw Anne move the cookie, so why wouldn't Sally also know? Young children fail to realize that Sally's mental representation of the situation, her access to information, can be different than their own. And apes who know sign language, but never ask us questions, are doing the same thing. They're failing to recognize that other individuals have similar cognitive abilities, and can be used as sources of information. So, we are all alone with our perceptions. We are alone in our own minds. We can both agree that chocolate tastes good. But, I cannot climb into your consciousness and experience what chocolate tastes like to you. I can never know if my red looks the same as your red. But, I can ask. So, stay human, stay curious, and let the entire world know that you are. And, as always, thanks for watching.