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Neuroscientist David Eagleman, PhD and physicist Sean Carroll, PhD challenge two assumptions we’re only beginning to question: that our reality is the reality, and that physics leaves no room for free will. Eagleman explains how genetics, brain wiring, and experience shape each person’s inner world. Carroll argues that even in a lawful universe, incomplete knowledge, counterfactual reasoning, and responsibility make our choices matter.
We created this video for Brain Briefs, a Big Think interview series created in partnership with Unlikely Collaborators. As a creative non-profit organization, they’re on a mission to help people challenge their perceptions and expand their thinking. Often, that growth can start with just a single unlikely question that makes you rethink your convictions and adjust your vantage point. Visit Perception Box to see more in this series.
Like it or not, the world that we really know and live in is one where our choices matter. We have some responsibility for bringing about what is going to happen next.
Why do we accept our reality as the uncontested truth? The interesting thing about the human brain in particular is that we drop into the world half-baked with a certain set of genetics. Now, as a result of the genetics being different, your brain wires up in slightly different ways.
You are a data collection machine that moves through the world, and you vacuum up your little bits of experience that you have. And in the end, whatever you have, that's what you assume to be true.
The first step to expanding our narrow models is to understand our own biases. Because everyone's not experiencing reality the same way on the inside.
For example, if I ask you to picture an ant crawling on a red and white tablecloth towards a jar of purple jelly, you might perceive that as a movie in your head. Or you might perceive it without any picture at all. People have completely different internal lives.
But with the endeavor of science and literature and philosophy, what we're able to do is step outside of ourselves and understand, "Hey, the way that I see the world isn't the only way to see the world. It's not the only truth." And the more we can get good at that, the more we can try to build a better society.
It's very often that in the conversations about free will, you find people who believe in free will contrasted with determinists who just think the laws of physics are gonna tell us what happens in the world.
A lot of people who are anti free will, the way they phrase it is, "I will believe that there's free will if there is a way that I could have acted differently." They are collections of particles, or you know, whatever physical system that is obeying the laws of physics. And in fact, they could not have acted differently 'cause the laws of physics are the laws of physics.
But the reality is, given the actual information you know about yourself, you could've acted differently, because the information you have about yourself is wildly incomplete. It's compatible with all sorts of different microscopic arrangements of what's going on in your brain and your body.
We have an ability to reason counterfactually, to think not about just what will happen, but of various things that could happen, and then pick the one that we think is a good one. And since we don't know the positions and velocities of every molecule in the universe, we can't say what would happen just given the laws of physics.
What we have to say is, "Given the choices I make, what is the future that I'm going to help bring about?"
