René Descartes： Dualism, Reflexes, and Living Machines

René Descartes is one of the most influential thinkers in psychology of all time, even though it didn't exist as a discipline for more than two centuries after his death. How's that possible? Stay tuned. Before we get started, subscribe to Sci vs. Sci, help us grow our channel, and we'll keep you in the loop on all things psychology. Picture this. The year is 1615. The place, it's France. The you is a man named René Descartes. Artist, philosopher, thinker, renaissance man. One day, you find yourself looking for some entertainment, and the buzz around town is that the royal palace has been renovated by the famous Italian Francini family, and they've been brought in to create water features in the royal gardens. You see, before the new French palace was built at Versailles, a huge and extravagant garden existed at Saint-Germain-en-Laye. In it, there were grottos with moving statues and fountains that displayed scenes from classical mythology. For example, at the Grotto of Perseus, every few minutes a dragon would rise from the water with flared nostrils and gaping maw, and Perseus would charge down from the ceiling above and thrust his sword to slay the dragon. Birds chirped, cherubs danced, and music played. This is the Grotto of Orpheus, drawn in 1615, at the time Descartes would have lived near the palace. Imagine this thing coming to life. This would be cool to watch today, much less in a time with no electricity or cars or Disneyland animatronic robots. To the people of the day, these scenes would have seemed to come alive. Like most people, Descartes was fascinated by this display and the mechanisms that created it. This concert of activity was all made possible by fluids moving through pipes and changes in water pressure, timed opening of valves. Programs were made with cogs and rope and counterweights so that everything played out in exactly the proper order. Now, Descartes was also a student of human and animal anatomy and fascinated by what it means to be alive and to move, much less think. He had taken it upon himself to dissect a few cadavers to learn about the body, and one of the things he noticed was that it was full of tubes. He noticed there were lots of fluids in the body, or spirits, which he called animal spirits, and he noticed that the pineal gland in the brain sat at the center of the ventricles, which are open spaces filled with spinal fluid. Descartes saw tubes and fluid and remembered the palace grottos, and he put two and two together. The movement of animal spirits through these tubes must be what gives us our life force and creates movement. We are just like the machines in the garden. When we encounter a noxious stimulus, such as stepping foot into the fire, the particles of the fire push on the area of that they touch, which tugs on a thread that's connected to them. This opens small pores in the brain, which allow the animal spirits to flow from the ventricles into the body, which withdraws the foot and moves the head and eyes to look at the stimulus. Descartes was describing a mechanism for a reflex for the first time ever, and it's thanks to them that we have the term reflex. The details may have been wrong, but he opened the door to understanding how our bodies could function in a mechanistic way, responding to stimuli without the need for some kind of supernatural intervention. And this was all over 200 years before we knew how the actual neuroanatomy worked. There was a problem though. While animals seemed to Descartes to be purely reflexive, acting in response to changes in their environment like little machines, humans, it seemed, were capable of much more. They could plan, they could make willful and purposeful movements of their own volition. How did Descartes deal with this? He created a concept called dualism, which is the idea that the mind and body are separate entities. To humans, God marries a soul, which allows them to voluntarily control their body. As proof, he tried a thought experiment. Can you imagine your mind without a body? He thought he could, and that was enough to show that you don't need a body to have the mind. Since the pineal gland was centrally located near the ventricles, and there was only one of them, unlike many structures in the brain, he deduced that the pineal gland was the most likely place to be the seat of the soul. While Descartes' study of reflexes inspired great progress in understanding the body, dualism hindered progress in the scientific study of the mind. Dualism assumes that the mind and body are made of different stuff and independent of each other, which means studying the body really doesn't tell you anything about the mind. Now, from a modern perspective, dualism is fraught with problems. After all, minds depend upon brains. As far as we can tell, there are no scientifically detectable instances of a mind without a brain or physical substrate of some kind. Damaging the brain damages the mind, which we see all the time in cases of stroke or brain injury that result in changes in personality or cognitive abilities. Indeed, modern neuroscientists are monists, mono as in one, as opposed to dualists. That is, we've discovered that the mind and body are truly inseparable. Despite its incongruence with the scientific evidence, however, even today dualism thrives among the general population. I feel a special connection to Descartes. He's a fascinating figure. Here are some other fun facts about him that you may or may not know. Besides his work on reflexes, he's also famous for his method of doubt. This meant that he questioned everything he knew with the hope that this might bring him to some philosophical bedrock if he could only find something that could not be doubted and was certainly true. He doubted everything, right down to the existence of his own body and his own mind. However, he noticed that if someone was there to do the doubting, then they must exist. Of this one fact he could be certain, and this was the foundation of his quote first philosophy. And he thought if that was a fact that was inescapably true, you could build an understanding of the world upon it. You're probably familiar with his famous phrase, cogito ergo sum, I think, therefore I am, showing that if there's someone there to do the thinking, that someone must exist. You're probably familiar with the Cartesian coordinate system you see on graphs, which was invented by and named after him. We do know that Descartes spent a lot of time in bed, and the apocryphal story is that he came up with the idea while lying in bed watching a fly bounce around the corner of his bedroom. He noticed that you could describe the position of the fly according to its corresponding location on the two walls. While we can't be sure the fly story is true, it's fun to think about. Speaking of lying in bed, he had a habit of sleeping until late in the day. However, he eventually took a tutoring job where they insisted that he wake up early, 5am, for lessons. Getting up early did not agree with him, however. He quickly got sick from the cold morning air, contracted pneumonia shortly thereafter, and died at the relatively young age of 54. I like to use this example as an excuse why I can't schedule any meetings before noon. Now for a salacious but fascinating rumor. Descartes was reported to have built a robot daughter that he carried with him in his travels. It was modeled after his actual daughter, Francine, who died at the young age of 5. The robot slept in a casket by his bed. This whole story is not well documented, so keep that in mind and take it with a grain of salt, but the idea that Descartes was so racked with guilt that he built something to help remember her and talk to her is kind of heart-wrenching. The story goes that he was traveling by ship with her in his cabin, and the superstitious crew of the ship were horrified when they discovered the robot, destroying it and tossing it overboard. This was on the way to that tutoring gig I was talking about earlier, and some say his grief from losing her again contributed to his ill health. In any case, Descartes was inspired by the technology of his day to help him understand how the body functions, much like we are inspired by computers with hardware and software, hard drives and RAM to describe things like short and long-term memory. Descartes' contributions set the stage for how we approach behavior scientifically, and his ideas are influential across many areas of study even today. If you found this video helpful, hit the like button, consider subscribing for more videos on all things psychology, and until next time, keep thinking! Oh look, here's a YouTube video of an automatic organ from around the same time as the grottos at the palace. Maybe we can use this to get a sense of what an automatic and programmed organ would have sounded like.