Descartes’ Error Summary

1-Sentence-Summary: Descartes’ Error will help you understand why the argument that the mind and body are disconnected is false by using neuroscience and interesting case studies to identify how the body and our emotions play a vital role in logical thinking.

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Are the mind and body separate? Or one and the same? The duality of mind and body is something that goes back to ancient Greece. And yet we mostly associate it with René Descartes, the French philosopher. Why is that?

Antonio Damasio’s Descartes’ Error: Emotion, Reason, and the Human Brain explains what’s going on, both with our emotions and this error in credit. You’ll discover what a man that survived a rod through his skull and one that took half an hour to decide on an appointment time have in common — and what it means for your own mind and body.

Here are the 3 main lessons of this book:

  1. Brain damage, like what Phineas Gage experienced, gives us clues about how the mind really works with the body. 
  2. Emotions are vital to our mind’s ability to function properly and think logically.
  3. Your brain uses feelings from past experiences to construct somatic markers which help it make decisions faster.

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Lesson 1: We can begin to understand the connection between the mind and body by looking into the experience of Phineas Gage.

To see the brain from the perspective of experimental neuropsychology, we need to look at case studies. Specifically of people who have had brain injuries by comparing their traits before and after their incident. Although there are many of these, the experience of Phineas Gage is the most interesting. 

Living in the 19th century, Gage worked on the railroad. He had a reputation for being dependable, diligent, and efficient. Thus his employer entrusted him with the dangerous job of setting the charges for demolitions.

One day in the summer of 1848, Gage set a charge for a small explosion to make way for the track like he’d done hundreds of times. But this time, it triggered an accident that sent a rod straight through his head. Miraculously, he survived and was even talking minutes later.

In the remaining decade or so of his life, however, Gage wasn’t himself. He began being impulsive and unconcerned for his future. He eventually lost his job with the railway and drifted between jobs until the end of his life. 

We now know that part of Gage’s brain was damaged in a way that affected his personality, including emotions. This brings an interesting light to the mind-body debate, but Gage is long gone so we can’t learn from him anymore. 

But today we have the author’s experience with a patient he refers to as Elliot who experienced similar brain damage and after-effects.

Lesson 2: Your brain receives guidance from your emotions to help you think logically.

Elliot’s tragic situation taught the author a lot about how the mind and body work together. Among all of their interactions, these two got to know each other, but the way that Elliot never seemed to express emotion puzzled the author.

He’d been through a lot, too, including job loss and divorce. After seeing pictures that were supposed to evoke emotion, he told the author outright that he just wasn’t experiencing emotions like he used to.

But these are emotions we’re talking about, not logical thinking abilities, right? Although Elliot struggled with those too, we might think that no emotions would make him better at reasoning skills, not worse.

The answer lies in how our body and mind use emotions to help us make sense of our experiences. We have our body state, which is our body’s system of letting our brain know how everything is doing. When we feel emotions, the body is also sending signals to our brain to let us know what to feel, think, and do. 

But at the same time, we have the emotional body state. Think of this like a picture album of past experiences and the feelings associated with them. Imagine a friend of yours, for example, and you might begin thinking of happiness or laughter from the fun times you’ve had with them. 

Our brain uses information from both of these types of signals from the body to help us decide what to do about the things around us. When you see your friend calling, for example, it tells you to answer because you know you’ll get some good laughs from talking to them.

Lesson 3: Somatic markers are a way the brain makes decisions faster by using feelings from past experiences.

Another curious experience the author had with Elliot was when scheduling an appointment. When the author suggested a couple of different dates, Elliot began deliberating all the different reasons each would be good or bad. 

The author decided to see how long this would go on. Half an hour later Elliot was still talking through it! After the author suggested one date, Elliot simply agreed and went on his way. 

This shows the way that our mind uses our experiences and emotions to create shortcuts that help us make decisions. In other words, feelings do play a role in logical thinking! 

Your brain uses what are known as somatic markers to attach certain thoughts or feelings about different choices you could make. Each option will have an emotion already attached to it from your life events that your mind can use to help you choose. And all of your past experiences contribute to these shortcuts, guiding you to know which way to go. 

When you consider a Monday meeting, for example, you don’t have to deliberate like Elliot to conclude that you don’t prefer them because the beginning of the week is busy. Instead, your brain uses the somatic markers from your experiences to automatically make the decision for you.

So if you want to be rational, your brain needs to be able to listen to the emotions that your body is feeling. The conclusion of the mind-body debate is that both are interconnected to help us think logically and function properly!

Descartes’ Error Review

I enjoyed Descartes’ Error. I’ve always liked psychology and philosophy and this book is a good blend of the two. However, it would be nice if it had more practical advice on how to use the principles it teaches.

Who would I recommend the Descartes’ Error summary to?

The 22-year-old college student who is studying psychology, the 37-year-old businessman who thinks that emotions have no use, and anyone that wants to learn more about the role that feelings have in logical thinking.

Last Updated on July 23, 2023

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Luke Rowley

With over 450 summaries that he contributed to Four Minute Books, first as a part-time writer, then as our full-time Managing Editor until late 2021, Luke is our second-most prolific writer. He's also a professional, licensed engineer, working in the solar industry. Next to his day job, he also runs Goal Engineering, a website dedicated to achieving your goals with a unique, 4-4-4 system. Luke is also a husband, father, 75 Hard finisher, and lover of the outdoors. He lives in Utah with his wife and 3 kids.