Is there an external reality? Of course there's an external reality. The world exists. It's just that we don't see it as it is.

We can never see it as it is. In fact, it's even useful to not see it as it is. And the reason is because we have no direct access to that physical world other than through our senses.

And because our senses conflate multiple aspects of that world, we can never know whether our perceptions are in any way accurate.

It's not so much do we see the world in the way that it really is, but do we actually even see it accurately?

And the answer is no, we don't. However paradoxical it sounds, if we think of what is visible as just what projects to the eyes, we see much more than is visible.

Let me give you an example. I walk into a room and there's graffiti on the wall and imagine it's graffiti that I find really offensive.

I look at it, I flush, my heart starts to race, I'm outraged, I'm taken aback. Of course, if I didn't know the language in which it was written, I could have had exactly the same retinal events and the same events in my early visual system, without any corresponding reaction.

Much more shows up for us than just what projects into our nervous system. Our senses are also making up the tastes, odors, and colors that we experience.

They're not properties of an objective reality. They're actually properties of our senses that they're fabricating.

By objective reality I mean what most physicists would mean, and that is that something is objectively real.

if it would continue to exist, even if there were no creatures to perceive it. Colors, odors, tastes, and so on are not real in that sense of objective reality.

They are real in a different sense. They're real experiences. Your headache is a real experience, even though it could not exist without you perceiving it.

So it exists in a different way than the objective reality that physicists talk about.

We always assume that our senses are telling us the truth. So it was quite a stunning shock to me when I realized that it's not just tastes, odors, and colors that are the fabrications of our senses and are not objectively real.

Space-time itself, and everything within space-time. Objects, electrons, quarks, the sun, the moon, their shapes, their masses, their velocities, all of these physical properties are also constructions.

Sometimes it's really difficult for people to understand that the data that your brain is receiving is meaningless because when they open their eyes, they look around, they say, "Well, I see everything.

What do you mean it's meaningless?" A really simple example is color.

Scientific knowledge of what light is shows us that our natural perception leaves a lot on the table.

The human perception of color is limited really by the principles of quantum mechanics. It's interesting to compare the human perception of color to the perception of sound.

When you have two pure tones together, like a C and a G, a simple chord, that's a fifth.

If you hear that, you can hear the separate tones, even though they're played together and you hear a chord, you can also sense the separate tones.

Whereas with colors, if you have two different colors, say spectral green and spectral red and mix them.

What you see is not a chord where you can see the distinct identities preserved, but rather an intermediate color.

In fact, you'll see something that looks like yellow. It's as if in music, when you play a C and a G together, instead of hearing a chord, you just heard the note E, the intermediate note.

So at this most basic level, we don't represent even the information we're getting in any accurate way.

And the reason is because it was useful to see it this way. So what you're seeing is the utility of the data, not the data.

Evolution by natural selection has shaped us with perceptions that are designed to keep us alive.

So if I see a snake, don't pick it up. If I see a cliff, don't jump off. If I see a train, don't step in front of it.

We have to take our perceptions seriously, but that does not entitle us to take them literally. Perception itself.

A perspective on something defined by perception is inherently a reduction of the information of the thing. My perspective of it is going to be a lot less total information than the actual thing is.

I can look at the object from the east side or the west side or the top or the north side or the inside, microscopically, telescopically; they'll all give me different information.

None will give me the entirety of the information about the situation.

So there is no all-encompassing perspective that gives me all of the information about almost any situation.

What this means is that reality itself is transperspectival. It can't be captured in any one perspective. So, multiple perspectives have to be taken.

All of which will have some part of the reality, some signal. There may also be distortion. I may be looking at the thing through a fisheye lens or through a colored lens that creates some distortion.

Why does this matter? The ability to take multiple perspectives, to see the partial truth in them, and then to be able to seam them together into something that isn't a perspective, it's a transperspective capacity to hold the relationships between many perspectives in a way that can inform our choice-making is fundamental to navigating reality well.

And how would we begin to know if what we think is true is actually true? This is the beginning of the scientific method.

Let us begin with observation, pose a question, figure out what the hypothesis would be that would answer a particular question, and then figure out how we would begin to address the hypothesis.

That is a scientific approach to questions that could be addressed any number of ways.

There is a kind of whispering campaign against the value of objective truth. Science's belief in objective truth works. Engineering technology based upon the science of objective truth achieves results.

It manages to build planes that get off the ground. It manages to send people to the moon and explore Mars with robotic vehicles on comets.

Science works; science produces antibiotics, vaccines that work.

So, anybody who chooses to say, "Oh, there's no such thing as objective truth. It's all subjective, it's all socially constructed." Tell that to a doctor, tell that to a space scientist; manifestly science works, and the view that there is no such thing as objective truth doesn't.

When you write down the theory, the theory then becomes your teacher. It becomes smarter than you in a way.

When Einstein wrote down the equations of general relativity, he did not know that they entailed the existence of black holes.

In that sense, the equations were smarter than Einstein. Einstein didn't believe in black holes for decades. The equations were very clear that they could exist.

Einstein said no. It turned out Einstein was wrong and the equations were right. So it's very interesting. We do these theories because we can learn from them.

When you try to address the nature of things, you may find that asking different questions requires different ways of processing the underlying reality.

For instance, understanding the human mind physically requires one kind of processing. And there's every reason to think that we already have fundamental physical laws that are adequate to that kind of treatment.

But to understand how a person works, how thought processes, moods, and so forth add up to a personality and a human actor will require quite different ways of understanding and quite different ways of processing the underlying information structure.

Is reality real? These neuroscientists don’t think so | Big Think

Big Think is the leading source of expert-driven, actionable, educational content -- with thousands of videos, featuring experts ranging from Bill Clinton to Bill Nye, we help you get smarter, faster. Get actionable lessons from the world’s greatest thinkers & doers. Our experts are either disrupting or leading their respective fields. We aim to help you explore the big ideas and core skills that define knowledge in the 21st century, so you can apply them to the questions and challenges in your own life. Other Frequent contributors include Michio Kaku & Neil DeGrasse Tyson.

Head to bigthink.com for a multitude of articles just as informative and satisfying as our videos. New articles posted daily on a range of intellectual topics. ​Join Big Think+ to gain access to an immense library of content. It features insight from many of the most celebrated and intelligent individuals in the world today.

   - Subscribe for daily videos.
   - Business inquiries and fan suggestions welcome.

Is reality real? These neuroscientists don’t think so | Big Think

Scripts