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.