 Hi Internet, my name's Josh and this is Thunk. I THUNK, therefore I am. Last week I talked about logical argumentation. Although it probably wasn't anything that most of my friends and hence viewership didn't know already, there were very few YouTube comments and so I've made two resolutions. First, I'm going to talk as fast as I possibly can. Second, more hats. More hats. More hats. Alright, so Cartesian dualism. You know if you wanted to make a team of the greatest minds in human history, Drenne Descartes would definitely be a first-round draft pick. Descartes was born on a Sunday in 1596 in Lahae and Durin, France, a place that later changed his name to Descartes because he's that important. He was an absolute genius in mathematics. He revolutionized algebra. He gave us the power notation that we're all familiar with. He laid the groundwork for calculus and he also gave us that handy little xy coordinate system that you learned in middle school that's named after him, like that town in France. But Descartes and his giant brain weren't just going to stop at revolutionizing mathematics. He was also one of the most prolific philosophers of his time. So much so that almost everybody knows a phrase that he coined in 1637 in his Discourse on the Method. J'paus d'unctus suite. I think, therefore I am. Descartes also thought about the human mind. He suggested that there were fundamentally two different kinds of stuff. Matter stuff and mind stuff. Matter stuff was what composed the stuff that was subject to the laws of physics. Stuff like rocks and planets and cubicle earth squeezy toys. In contrast, mind stuff wasn't subject to the laws of physics and it made up things like human consciousness and thought. This model of the mind is being attached to, but separate from the body is also named after Descartes. Cartesian dualism. More generally, it's called substance dualism because it suggests that there are two kinds of substances and although mind stuff and matter stuff can affect each other, they're not the same thing. Now there are a ton of war games that you can play with how you define consciousness and mind, but what do you think? Is the mind made of something other than the brain? Hat change. Descartes was definitely one of the staggering intellects of human history, but he was writing the tail end of the Renaissance and the field of neuroscience was pretty abysmal at that time. How abysmal? Well, it took almost two centuries after his death for somebody to discover neurons. Even so, Descartes suggested that there were things that called animal spirits that ran up and down the nerves and carried sensation from the extremities to the brain. After a few centuries of neuroscience, this theory has been revised somewhat. We now know that what makes up the nervous system are cells called neurons, which chatter at each other with chemicals called neurotransmitters, turning each other on and off. We also know that the brain is a dense cluster of highly networked neurons. Now, that's an intensely complex system, but it still functions entirely on chemistry. In fact, there are a few ways that we found to change that chemistry. Techniques like deep brain stimulation work directly on the mechanisms that neurons use to communicate with each other, and in so doing, can fundamentally change how a person feels and thinks. I want to emphasize that changing the balance and exchange of chemicals in your brain changes how and what you think. If there was some sort of floaty mind substance that wasn't connected to the physical world, don't you think that it would at least be a little bit immune to the effects of chemicals? I mean, if you were to suggest that the physiological addiction to heroin has nothing to do with the mind, isn't that putting Descartes before the horse? I think that what we call mind is an emergent phenomenon, that is, something that appears complex, which arises from simple interactions between simple things. Think of a snowflake. Water molecules aren't driven by any external force that desires beauty. They simply follow the laws of chemistry, which cause them to crystallize into beautiful shapes. The beauty in something that's contained within the water molecules themselves is just something that happens when they follow the rules of chemistry. It's also intrinsically tied to the nature and behavior of those molecules. It is an emergent property of water. Similarly, the neurons that compose a brain don't have any mind in them. Mind is just something that happens when you get 100 billion neurons together, networked, and talking to each other in a particular pattern. That would mean that Descartes, despite having a lot of things right for his day, was wrong, and that there's no such thing as mind stuff or matter stuff, just matter stuff behaving in a particular pattern that we've decided to call the mind. What do you think? Is the term mind just a name for what happens when a bunch of neurons talk to each other, or was Descartes onto something? Is there something about the mind that is greater than the sum of neurochemistry happening in the brain, and how would you prove it? Oh look, a comment box! Thanks for watching! Next week I'm going to talk about artificial intelligence. If you'd like to read up on it, I've left some links below. Blah, blah, subscribe, blah, share, and I'll see you next week!