Strange thoughts about brains: a casual conversation

“My neurobiology lecture this morning was pretty challenging. It was about theories of how the brain does logical reasoning. They still don’t really understand it. Left me wondering about how the brain can think logically at all.”

“What do you mean?”

“Well, the brain is just composed of atoms which have formed synapses and neurons. Thinking is just electrical currents in the neurons and the movement of chemical in the synapses. So how do those physical processes produce logical thinking? And how do I make them do the thinking I want to do?”

“I don’t think that’s the right way to look at it. We don’t sit outside our brains making them do what we want. Our brains are us. And they’ve evolved by natural selection, just like the rest of us. So they have evolved to think logically. Where’s the problem?”

“If a synapse receives an electrical signal, a chemical neurotransmitter is released that causes another neuron to generate another electrical signal. It all happens according to physical cause and effect laws. But to do logic, we have to use logical processes or laws – like, if something is true then something else is true. That is completely different to physical laws. I just can’t see how the electrical and chemical processes can be controlled by physical laws yet still do logic.”

“A computer can do it. A computer is just a bunch of circuits with electrical signals, all controlled by the laws of physics. Yet they can do pretty impressive logic and mathematics.”

“But the computer hardware and software were designed to do that. Computers have to be programmed, and if there’s a bug in the program, they don’t work properly. And if no-one programs them, computers can’t do anything!”

“But we know that evolution and natural selection work just like a designer. It just takes a lot longer to get there. But over time, our brains got better and better as the bad thinkers didn’t survive so well, and their good thinkers passed on their genes. It started with apes or maybe further back, but eventually humans evolved with pretty smart brains – if only people would use them!”

“Ha! You’re right! But that’s what I don’t get. Natural selection means those animals that survive better and reproduce better pass on their genes. It doesn’t select for good thinking. Just survival and reproduction. The ability to think logically is just a lucky accident.”

“But surely animals, and humans, who think better are more likely to survive!? There must be many situations where a smart animal will find food or avoid a predator, but a dumb animal misses out?

“How do you reckon that happens? I mean – give me an example.”

“I think there are lots of examples. Like a smarter animal would learn better from past experience, like, maybe, remembering that a lion is more likely to attack an animal separated from the herd. And so the smart animal stays in the middle of the herd. Or maybe an ape learns to use simple tools. I read that some monkeys make sponges out of leaves and moss that suck up water. They use these for grooming and keeping clean, which I suppose makes them more attractive to a potential mate.”

“But surely that’s just pretty basic thinking, trying something new, learning and remembering? It doesn’t really require a lot of thinking, certainly not theoretical or logical thinking.”

“But all thinking’s the same, in principle. If you can do simple thinking, natural selection will help generations after you to gradually think better as the smarter ones survive and reproduce that little bit better.”

“I really doubt that. I can think of lots of reasons why very basic practical survival thinking will evolve but higher theoretical thinking will be a liability.”

“Really? How could thinking be a liability?”

“Deeper thinking requires time and energy, and in the wild, animals don’t always have that. If a zebra stops to think logically about whether a rustle in the long grass is a lion, it may be too late. It has to react instantly. Bearing young and raising them takes longer with larger brain capacity, and that can leave the mother vulnerable for longer periods. So I reckon brains would evolve to be smart enough to react, but not further than that.

“But that can’t be right can it? After all, we are here and using reasoning. If evolution can produce an eye, surely it can produce a smart brain too?”

“Obviously you’re right. But I still can’t see how our thinking can only be the physical processes we know about. There’s got to be something more going on.”

“Yeah, you’ve got me thinking about it too now. But I think science will work it out. We’ve learnt so much about the brain in the last few decades.”

“From what I’ve been learning, I’m not sure science is looking at some of these questions. Sure, we know more about the physics of the brain, because we can do scan and stuff. But I don’t know if scientists are even thinking about these more philosophical questions.”