When you open your eyes, do you see the world as it really is? Humans have been asking themselves this for thousands of years. From the shadows on the wall of Plato’s cave in The Republic to Morpheus offering Neo the red or the blue pill in The Matrix, the notion that what we see might not be what is truly there has troubled and tantalised us.

In the 18th century, the philosopher Immanuel Kant argued that we can never have access to the Ding an sich, the unfiltered “thing in itself ” of objective reality. Great minds have taken up this perplexing question again and again. They all had theories, but now neuroscience has an answer.

The answer is that we don’t see reality. The world exists. It’s just that we don’t see it. We do not experience the world as it is because our brain didn’t evolve to do so.

In terms of the sheer number of neural connections, just 10% of the information our brains use to see comes from our eyes. Perception derives not just from our five senses, but from our brain’s seemingly infinitely sophisticated network that makes sense of all the incoming information. But why does any of this matter? Why might we need to deviate from the way we perceive?

Perception matters because it underpins everything we think, know and believe. Our sense of self, our most essential way of understanding existence, begins and ends with perception. The death that we all fear is less the death of the body and more the death of perception. Yet most of us don’t know how or why our brain evolved to perceive the way it does.

Our brain is an embodiment of our ancestors’ perceptual reflexes, shaped by natural selection, combined with our reflexes and those of our culture. So, if the brain is a manifestation of our history, how can we step outside the past to live and create differently in the future? Because humans have the wild and generative gift of being able to see their lives and affect them just by reflecting on the process of perception itself. We can see ourselves see.

But stepping back and questioning how we see means embracing uncertainty. All brains are deathly afraid of uncertainty, for good reason. “Not knowing” is an evolutionarily bad idea. If our ancestors paused because they weren’t sure if the dark shape in front of them was a shadow or a predator, it was already too late. We evolved to predict. Why are all horror films shot in the dark? Think of the feeling you have when walking through a familiar forest at night, compared to during the day. At night, you can’t see what’s around you. You’re uncertain. It’s frightening, much like the constant “firsts” in life – the first day of school, first dates, the first time giving a speech. We don’t know what’s going to happen, so these situations cause our bodies and our minds to react.

Uncertainty is the problem that our brains evolved to solve. Life is inherently uncertain because the world and the things in it are always changing. An increasingly connected world is also inherently more unpredictable. In this context, doubt is often disparaged in our culture because it is associated with indecision, a lack of confidence and weakness. I argue the opposite.

We need to embrace the perceptual power of doubt and the humility that comes with understanding our own brains. It’s about why we see what we do, and how recognising that we don’t have access to reality leads us to get more things right. What is the next greatest innovation? It’s not a technology, it’s a way of seeing.

Deviate: The Science of Seeing Differently by Beau Lotto is published on 27 April by Weidenfeld & Nicolson at £20. Order a copy for £15 from bookshop.theguardian.com