Reason versus experience in how we know the world

HostI was looking at a map of a hiking trail this morning and I realized I knew every turn and every hill on paper. But then I got out there and my legs started burning and the wind was hitting my face and I realized I didn't really know that trail at all. It got me thinking about how there's this big gap between what we know in our heads and what we know because we've actually lived it. Is one of those ways of knowing more true than the other?

GuestWell, people have been arguing about that for a long time. They usually put it into two camps. On one side, you have the idea that the only way to really know anything is to go out and touch it, see it, and test it. That's the explorer's view. But then there's this other side that says our senses are kind of messy and they can be fooled. Those people think that the only things we can really be sure about are things we work out with pure logic, like math. It's the difference between seeing a bird and knowing that two plus two equals four.

HostBut those feel so different. I mean, if I sit in a dark room and think really hard, I'm never going to know what a strawberry tastes like. I have to go eat the strawberry. Isn't experience just the way we get all our data?

GuestThat's what a lot of people think. They'd say our minds start out like a blank sheet of paper and the world writes on it through our eyes and ears. Think about a fire. You can read a book that says fire is hot, but you don't truly know what hot means until you feel the heat on your skin. That kind of knowing is built from the outside in. It's solid because it's tied to the real world. But here's the problem. Our senses aren't perfect. If you put your hand in lukewarm water after holding an ice cube, that water feels hot. If you put it in after being in a sauna, it feels cold. So, is the water hot or cold? Your experience is telling you two different things about the same bowl of water.

HostOkay, so my skin is lying to me. But that's why we have thermometers, right? We use tools to be more objective.

GuestSure, but even then, you're still relying on your eyes to read the number on the screen. The other camp would say that if you want the truth, you have to look at things that don't depend on your shaky senses. Think about a circle. In the real world, there's no such thing as a perfect circle. Every wheel, every coin, every drawing has tiny bumps if you look close enough. But in your mind, you can know exactly what a perfect circle is. You can work out the rules for it and they're always true, even if you never see one in real life. That kind of knowing is built from the inside out. It's clean and it never changes.

HostThat sounds a bit like we're just playing with ideas though. If these perfect circles don't exist in the world, why does it matter that I can think about them? It feels like logic is just a game we play in our heads while the real world is happening somewhere else.

GuestI wouldn't say that. Think about how we build things. A guy sitting at a desk can use math to work out if a bridge will hold a thousand trucks. He doesn't have to build the bridge first and wait for it to fall down to know if it works. He uses reason to see into the future. That's pretty powerful. He's using rules that are true whether he's on the bridge or not. The friction comes when we try to figure out where those rules come from. Did we find them under a rock, or were they already in our heads when we were born?

HostSee, that's where I get stuck. I feel like I only know those rules because I saw things in the world first. I saw two apples and another two apples and learned they make four. I didn't just wake up knowing math. So doesn't experience still come first?

GuestNot necessarily. There are some things that seem to be there before we even start looking. Like the idea that something can't be a cat and not a cat at the same time. You don't need to go around the world checking every cat to be sure of that. You just know it because it's a rule of how thinking works. But you're right that we need both. There was a famous thinker who said that thoughts without content are empty, but seeing things without a way to organize them is blind. It's like having a map but no ground to walk on, or walking in the woods without a map. You need the map to make sense of where you're stepping, but the map isn't the forest.

HostSo it's not really a competition. It's more like a loop. I use my head to make sense of what I'm seeing, but I use what I'm seeing to check if my head is right.

GuestYeah, and the really interesting part is where they don't match up. Like when we look at the stars. To our eyes, it looks like the sun goes around the earth. That's our direct experience every single day. But our reason tells us that's not what's happening at all. We had to use math and logic to figure out that our eyes were wrong. So, in that case, the thinking part actually got us closer to the truth than our own two eyes did.

HostIt's weird to think that the less I trust what I see, the more I might actually understand.

GuestIt's a bit of a trade-off. Experience gives you the color and the feeling of life, but reasoning gives you the skeleton that holds it all together. You can't really have one without the other if you want to get the full picture. We're always toggling back and forth between what we feel and what we know must be true. Even if we could know everything just by thinking, it would be a pretty grey and boring world. But if we only went by what we felt, we'd be lost in a fog of things that change the moment we turn our heads.

HostThe trail map told me exactly where the path was, but it couldn't tell me how the air would smell or how tired I'd be by the time I reached the top.

GuestThe map is a perfect set of lines that stays the same in the rain, but the mud on your boots is what tells you that you've actually arrived.

HostThose lines on the paper stay steady while my legs do the climbing.